2008 AIR QUALITY MANAGEMENT PLAN

Transcription

1 2008 AIR QUALITY MANAGEMENT PLAN August 2008 Monterey Bay Unified Air Pollution Control District Silver Cloud Court Monterey, California 93940

2 2008 AIR QUALITY MANAGEMENT PLAN FOR THE MONTEREY BAY REGION Sixth* Revision to the 1991 Air Quality Management Plan for the Monterey Bay Region Prepared by Monterey Bay Unified Air Pollution Control District August 2008 *Fifth Revision June 2008 Sixth Revision Incorporated 2008 Population Forecast for the Monterey Region

3 MONTEREY BAY UNIFIED AIR POLLUTION CONTROL DISTRICT GOVERNING BOARD Chair: Vice Chair: Reb Monaco San Benito County Simon Salinas Monterey County Members: Lou Calcagno Monterey County Tony Campos Santa Cruz County Dennis Donohue City of Salinas Doug Emerson San Benito County Cities Gary Wilmot Monterey Peninsula Cities Ellen Pirie Santa Cruz County Ila Mettee-McCutchon Monterey County Sam Storey Santa Cruz County Cities George Worthy South Monterey County Cities Air Pollution Control Officer Douglas Quetin *Fifth Revision June 2008 Sixth Revision Incorporated 2008 Population Forecast for the Monterey Region

4 STAFF CONTRIBUTIONS The following individuals contributed to the preparation of the 2008 Air Quality Management Plan for the Monterey Bay Region: Monterey Bay Unified Air Pollution Control District Jean Getchell, Supervising Planner Bob Nunes, Air Quality Planner Dave Fairchild, Transportation/Air Quality Planner David Craft, Air Quality Engineer Mike Sewell, Air Quality Engineer Julia Duran, Senior Administrative Assistant Association of Monterey Bay Area Governments Katie Axt, Planner Bhupendra Patel, Senior Transportation Modeler Mark Griffin, Director of Planning *Fifth Revision June 2008 Sixth Revision Incorporated 2008 Population Forecast for the Monterey Region

5 This page is intentionally blank. *Fifth Revision June 2008 Sixth Revision Incorporated 2008 Population Forecast for the Monterey Region

6 2008 AIR QUALITY MANAGEMENT PLAN FOR THE MONTEREY BAY REGION TABLE OF CONTENTS EXECUTIVE SUMMARY ES INTRODUCTION 1.1 Planning Area and Air Basin Description Population State Air Quality Planning Requirements AMBIENT AIR QUALITY 2.1 Ambient Air Quality Standards Ambient Air Monitoring Network Area Designations and Attainment Status Ambient Air Quality Air Basin Exceedance Trend Seasonal Exceedance Pattern ARB Air Quality Indicators 2-7 (1) Peak Concentration or Hot Spot Indicator 2-8 (2) Overview of ARB Exposure Indicators 2-10 (3) Population Exposure Indicator 2-10 (4) Area Exposure Indicator Trends at Individual Stations Transport HEALTH AND ENVIRONMENTAL EFFECTS OF GROUND-LEVEL OZONE 3.1 Introduction Health Effects The Children s Health Study Environmental Effects Health Benefits of Revised Standard EMISSION INVENTORY AND FORECASTS 4.1 Introduction Structure of the Emission Inventory Emission Forecasts Emission Inventory and Trends Stationary Sources 4-3

7 4.4.2 Area-wide Sources Mobile Source Emissions 4-4 (1) On-Road Motor Vehicle Emissions EMFAC Model 4-5 (2) On-Road Motor Vehicle Activity AMBAG Travel Data 4-5 (3) Emissions from On-Road Motor Vehicles 4-5 (4) Other Mobile Sources OFFROAD Model Natural Sources Population Trends and Emissions Effect of District Rules on Emissions ACHIEVING AND MAINTAINING THE STATE OZONE STANDARD 5.1 Introduction Maintaining the 1-Hour Standard Meeting and Maintaining the 8-Hour Standard Emission Reduction Requirements for Nonattainment Areas Ozone Design Value Strategy All Feasible Measures ARB Transport Assessments Vintage of Existing Assessments Summary of Existing Assessments Application to Current Conditions Findings from Photochemical Modeling Project Transport Modeling Episodic Patterns Year 2010 Projections Meeting and Maintaining the State Ozone Standard Regional Scope ARB Transport Mitigation Requirements Potential Benefits of the 2006 Global Warming Solutions Act Projecting an Attainment Date Hour Standard Hour Standard Air Quality Trend Approach Hour Standard Emission Inventory Trend Approach Synopsis CONTROL MEASURES 6.1 Introduction Adopted Control Measures Contingency Control Measures Contingency Control Measures Deleted from Consideration 6-9

8 7.0 TRANSPORTATION CONTROL MEASURES 7.1 Background Description of Adopted TCMS Improved Public Transit Service (New Service and Operations to Increase 7-1 Ridership) Expand Transportation Demand Management Signal Synchronization New and Improved Bicycle Facilities Alternative Fuels Regional Initiatives to Improve Air Quality Operational Intelligent Transportation Systems AB 2766 (DMV Fee Surcharge) Motor Vehicle Emissions Reduction 7-8 Grant Program 7.4 Reductions in the Rate of Increase of Vehicle Trips and Miles Traveled IMPLEMENTATION OF THE AIR QUALITY MANAGEMENT PLAN FOR THE MONTEREY BAY REGION 8.1 Background for the Monterey Bay 8-2 Region 8.3 Summary of Rule Activity from 1987 through the End of the Report 8-2 Year 8.4 Summary of Planned Adoption and Implementation and Rule 8-3 Effectiveness Versus Actual Adoption, Implementation and Rule Effectiveness 8.5 Where Measures are Pending, a More Detailed Description of 8-4 Projected Workshop and Adoption Dates 8.6 Explanation of Any Significant Deviations from the Original Plan 8-4 Schedule for Adoption and Implementation 8.7 Activity in Transportation Control Measures (TCM) and Indirect 8-4 Source Review Implementation Improved Public Transit Service (New Service and Operations to Increase 8-6 Ridership) Expanded Transportation Demand Management Signal Synchronization New and Improved Bicycle Facilities Alternative Fuels Regional Initiatives to Improve Air Quality Selected Intelligent Transportation System AB 2766 DMV Motor Vehicle Emissions Reduction Grant Program 8-13

9 8.7.9 Indirect Source Review Implementation Ambient Air Quality Data and Attainment for the State Ozone 8-15 Standard

10 TABLES AND FIGURES Tables Pages Table 1-1 Population Forecasts for North Central Coast Air Basin 1-4 Table 2-1 Ambient Air Quality Standards 2-2 Table 2-2 Attainment Status for the North Central Coast Air Basin 2-5 Table 2-3 Peak Day Concentrations by Stations 2-12 Table 4-1 Emission Inventory & Forecasts for Volatile Organic Compounds for 4-9 the North Central Coast Air Basin Table 4-2 Emission Inventory and Forecasts for Oxides of Nitrogen for the North 4-12 Central Coast Air Basin Table 4-3 Adopted District Rules Limiting Emissions of Ozone Precursor Gases 4-10 Table 5-1 Regulatory Transport Couples and Degree of Impact on NCCAB 5-15 Table 6-1 Feasible Control Measures Estimated Emission Reductions and Cost 6-10 Effectiveness Table Improved Public Service Transit Projects in FY 2006/07 to FY 2009/ MTIP Table Transportation Demand Management Projects in FY 2006/2007 to FY /10 MTIP Table Signal Synchronization Projects in the FY 2006/07 to FY 2009/ MTIP Table Bicycle Facility Projects in FY 2006/07 to FY 2009/10 MTIP 7-5 Table 7-5 Alternative Fuels Projects in FY 2006/07 to FY 2009/10 MTIP 7-6 Table Regional Comprehensive Planning Projects in FY to 7-7 FY 2009/10 MTIP Table Selective Intelligent Transportation Projects in FY to 7-8 FY 2009/10 MTIP Table AB2766 Grants Awarded in 2000 thru FY Table 8.7 Summary of Daily Reductions for VMT, Vehicle Trips and Emissions 8-5 for Each Adopted TCM in Tons per Day (TPD) Table Reductions in VMT, Trips, Emissions, and Cost/Benefit of Improved 8-7 Public Transit Related TCMs Table Reductions in VMT, Trips, Emissions, and Cost/Benefit of Expanded 8-8 Transportation Demand Management Related TCMs Table Reductions in VMT, Trips, Emissions, and Cost/Benefit of Signal Synchronization Related TCMs 8-9 Table Table Reductions in VMT, Trips, Emissions, and Cost/Benefit of Bicycle Facilities Related TCMs Reductions in VMT, Trips, Emissions, and Cost/Benefit of Alternative Fuels Related TCMs

11 Table AB 2766 DMV Motor Vehicle Emissions Reduction Grant Projects Funded from for which Emissions Reductions can be Estimated 8-14

12 Figures Figure 2-1 Map of the North Central Air Basin and the Area s Air Monitoring 2-4 Network Figure 2-2 NCCAB Exceedance Days 1988 to Figure 2-3 Seasonal Distribution 1 and 8-Hr. Exceedances 2-7 Figure 2-4a Pinnacles NM- NCCAB Hot Spots 2-8 Figure 2-4b NCCAB 8-Hour EPDC Pinnacles NM-NCCAB Hot Spot 2-9 Figure 2-5 Population Weighted 1-Hour Exposure Indicator 2-10 Figure 2-6 Area Weighted 1-Hour Exposure Indicator 2-11 Figure 2-7 Scotts Valley Peak Ozone Trend 2-13 Figure 2-8 Carmel Valley Peak Ozone Trend 2-13 Figure 2-9 Santa Cruz Peak Ozone Trend 2-13 Figure 2-10 NCCAB Population Weighted Indicator 2-13 Figure 2-11 NCCAB Area Weighted Indicator 2-13 Figure 2-12 Pinnacles Nitrate v. Ozone Trends 2-14 Figure Emission Inventory for VOC 4-11 Figure Emission Inventory for VOC 4-11 Figure Emission Inventory for NO x 4-12 Figure Emission Inventory for NO x 4-12 Figure 4-5 NCCAB VOC and NO x Emission Inventory Trend 4-13 Figure 4-6 NCCAB Emission and Population Trends 4-14 Figure 4-7 Comparison of Population Forecasts Used for 2000 and 2004 AQMP 4-14 Figure 4-8 NCCAB VMT v. Population Growth 4-14 Figure 4-9 Comparison of EMFAC2000 to EMFAC Figure 4-10 Comparison of Motor Vehicle Emissions with VMT 4-15 Figure 4-11 Comparison of NCCAB VMT Activity Data 4-15 Figure 4-12 Effect of High Growth Categories on Stationary Source Emissions 4-16 Figure 4-13 Effect of District Rules 431 and Figure vs Model 5-13 Figure 5-2 Potential NCCAB 8-Hour Attainment Date 5-14 Figure 5-3 Regional NOx Trand SFBA + NCC 5-14 GLOSSARY APPENDIX A: APPENDIX B: DETAILED EMISSION INVENTORY AND FORECASTS FOR STATIONARY, AREA AND OTHER MOBILE SOURCES DETAILED EMISSION INVENTORY AND FORECASTS FOR ON-ROAD MOTOR VEHICLES (EMFAC 2007)

13 This page is intentionally blank.

14 EXECUTIVE SUMMARY The Monterey Bay Unified Air Pollution Control District is one of 35 air districts established to protect air quality in California. Its jurisdiction is the North Central Coast Air Basin (NCCAB), comprised of Monterey, Santa Cruz and San Benito counties. In 1988, the State Legislature adopted the California Clean Air Act (CCAA), which required each nonattainment district in the State to adopt a plan showing how the State Ambient Air Quality Standard (AAQS) for ozone would be met in their area of jurisdiction. The CCAA (Health & Safety Code et seq.) required initial preparation of an Air Quality Management Plan (AQMP) in 1991, with subsequent updates every three years. This is the fifth update to the 1991 AQMP. There have been many changes both in terms of air quality and the regulatory setting since the initial AQMP in In particular, in 2006 the California Air Resources Board (ARB) revised the State AAQS and made it considerably more stringent by adding an 8-hour average to the standard, which previously only included a 1-hour average. Both components of the standard must now be met before the ARB can designate that an area has attained the standard The 2008 AQMP is a transitional plan shifting focus of our efforts from achieving the 1- hour component of the State AAQS to achieving the new 8-hour requirement. The plan includes an updated air quality trends analysis, which now reflects both the 1 and 8-hour standards, as well as an updated emission inventory, which includes the latest information on stationary, area and mobile emission sources. Although the air basin actually achieved the 1-hour standard in 2006, this was the same year the 8-hour standard was introduced. Consequently, in November 2006, the ARB designated the air basin a nonattainment area for the State AAQS for ozone. The 2008 AQMP includes 5 control measures from the 2004 AQMP, whose development was put on hold pending our progress toward achieving the 1-hour standard. Since with the introduction of the 8-hour standard, the area has reverted to nonattainment, the 2008 AQMP proposes to follow through on development of these previously adopted measures. The five measures include: A1 - Solvent Cleaning Operations A2 - Degreasing Operations A3 - Spray Booths - Miscellaneous Coatings and Cleanup Solvents A4 - Adhesives and Sealants A5 - Natural Gas-Fired Fan-Type Central Furnaces and Residential Water Heaters For 2010, the combined emission reductions from these measures are estimated to be 1.65 tons per day of VOC and 0.17 tons per day of NO x. The 2008 AQMP also updates the description of the area s Transportation Control Measures (TCM s), as well as grant activity under AB 2766 and the Moyer mobile source emission reduction programs. The AQMP further proposes to evaluate any co-pollutant benefits in terms of reducing ozone precursors achieved under climate change bill AB 32. ES-1

15 This page intentionally left blank. ES-2

16 1.0 INTRODUCTION 1.1 PLANNING AREA AND AIR BASIN DESCRIPTION The planning area is the North Central Coast Air Basin (NCCAB), which consists of Monterey, Santa Cruz, and San Benito counties. The air basin forms an area of more than 5,100 square miles. With Monterey County covering over 3,320 square miles and Santa Cruz County covering only 445 square miles, the planning area consists of one of the largest and one of the smallest counties in the state. The planning area features varied vegetation, climate and geography. It includes portions of several mountain ranges: the Santa Lucia and Gabilan Ranges in Monterey and San Benito Counties, the southern portion of the Santa Cruz Mountains in Santa Cruz County, and the Diablo Range in the eastern half of San Benito County. The coastal terraces in the Santa Cruz area, the flat plains surrounding Watsonville, Salinas, and King City, and the southern Santa Clara Valley are sharply defined by the various mountain ranges. The dominant land use in the region is agriculture with approximately 1,626,000 agricultural acres or 437,000 farmed acres (pasture land excluded). About 88 percent of farmed agricultural land is in the Salinas Valley with 6 percent in San Benito County and 6 percent in Santa Cruz County. Based on the 2005 Crops Reports (1), the gross agricultural crop value was $3.27 billion in Monterey County, $269 million in San Benito County and $418 million in Santa Cruz County for a total of nearly $ 4.0 billion. Institutional land uses occupy significant portions of the land area within the region. Military land uses in Monterey County include Fort Hunter-Liggett, Camp Roberts, the Naval Postgraduate School, and the Presidio of Monterey. Other major institutional uses are the University of California at Santa Cruz (UCSC) and the Soledad Correctional Facility. Fort Ord, comprising almost 28,000 acres, was closed in The state University at Monterey Bay and UCSC have received over 2,000 acres of Fort Ord land for education and research uses. The region has a significant amount of land in open space and recreation uses including several large State Parks, the Ventana Wilderness (164,503 acres), the Los Padres National Forest (304,035 acres), and the Pinnacles National Monument. Over 17,000 acres of Fort Ord have been dedicated to open space and recreational uses. The California Department of Parks and Recreation operates over 25 visitor facilities in the region. In Monterey and Santa Cruz counties urbanized development occupies about three percent of the land area with approximately 65 percent of regional urban development in Monterey and Santa Cruz Counties extending around Monterey Bay on the coastal plain from the Cities of Santa Cruz to Carmel-by-the-Sea. Salinas is an exception, lying more than ten miles 1-1 August 20, 2008 Revision Incorporation of Monterey Bay Area 2008 Regional Forecast

17 inland from Monterey Bay. Nearly three-quarters of the urban development is for residential purposes. Commercial land uses are concentrated in the major urban centers of the counties including Santa Cruz-Capitola, Monterey Peninsula, and Salinas. Tourism is also a major segment of the economic market in these areas. Industrial activity includes oil production (San Ardo oil field), power generation (Moss Landing), commercial fishing (Moss Landing), cement manufacturing (Davenport), quarrying activities (all three counties), agricultural processing in the Salinas and Watsonville areas, sand mining (Hollister, Marina, Scotts Valley and the North Coast of Santa Cruz County), food processors (Salinas, Watsonville and Santa Cruz) and electronic manufacturing firms (Scotts Valley, Santa Cruz, Watsonville and Salinas). Approximately 97 percent of San Benito County is unincorporated land, with 90 percent being used as farmland, rangelands, forest, and public lands. The bulk of the county's population resides in the central region near the incorporated cities of Hollister and San Juan Bautista. Hollister serves as the major commercial center for the county. Each county and city in the region has an adopted comprehensive general plan for its physical development. Each of the plans generally accommodates a certain amount of residential, commercial, industrial and institutional development. 1.2 POPULATION Population data for the area are developed by federal, state and local agencies. The U. S. Census Bureau conducts a physical count of the population once every ten years, with the last decennial census in the year The California Department of Finance (DOF) releases annual population estimates to complement the decennial census. The most recent DOF figures are for the year The NCCAB s regional Metropolitan Planning Organization, the Association of Monterey Bay Area Governments (AMBAG), periodically develops population forecasts several decades into the future which reflect the most recent economic and population growth data. Historically, the AMBAG forecasts for a given year have been a few percentage points higher than the corresponding DOF figure. The most recent population forecasts, adopted by AMBAG on June 11, 2008, are presented in Table 1-1. The current AMBAG population figures in part represent constrained forecasts where limitations to growth due to such factors as the availability of water, wastewater treatment and local growth policies are taken into account. DOF figures for 2007 indicate that the air basin is home to approximately 747,888 people with 57 percent residing in Monterey County, 35 percent in Santa Cruz County, and 8 percent in San Benito County. (2) AMBAG forecasts the area to grow to about 991,369 persons by In terms of the population of California s fifteen air basins, the NCCAB ranks in the middle as having the eighth largest population. The South Coast Air Basin is the largest with a 1-2 August 20, 2008 Revision Incorporation of Monterey Bay Area 2008 Regional Forecast

18 2005 population of nearly 16 million, while the Great Basin Valleys is the smallest with a 2005 population of only 33, STATE AIR QUALITY PLANNING REQUIREMENTS The air basin is a nonattainment area for the State Ambient Air Quality Standards for both ozone and inhalable particulate matter (PM 10 ). The 1991 Air Quality Management Plan for the Monterey Bay Area (AQMP) was the first plan prepared in response to the California Clean Air Act of 1988 that established specific planning requirements to meet the ozone standard. The Act requires that the AQMP be updated every three years. This is the fifth update to the 1991 AQMP with the first four completed in 1994, 1997, 2000 and 2004, respectively. The AQMP addresses only attainment of the State ozone standard. Attainment of the State PM 10 standard is addressed in the District s plan Senate Bill 656 Implementation Plan which was adopted in December Maintenance of the National eight-hour standard for ozone is addressed in the District s Federal Maintenance Plan for the Monterey Bay Region, which was adopted in March The California Clean Air Act also requires the District to prepare and submit a report to ARB summarizing progress in meeting the schedules for developing, adopting or implementing the air pollution control measures contained in the District's plans. The report is due by December 31 of each year and is included in Chapter 8 of this plan. 1-3 August 20, 2008 Revision Incorporation of Monterey Bay Area 2008 Regional Forecast

19 TABLE 1-1 POPULATION FORECASTS FOR NORTH CENTRAL COAST AIR BASIN 1 Area MONTEREY COUNTY Carmel 4,091 4,075 3,873 4,007 4,033 Del Rey Oaks 1,647 1,627 2,237 3,197 3,171 Gonzalez 8,399 10,831 15,969 20,941 23,418 Greenfield 13,357 17,795 21,855 27,348 30,337 King City 11,430 13,540 17,269 22,482 24,726 Marina 19,051 24,551 29,274 32,010 32,942 Monterey 30,467 30,106 30,278 30,650 30,836 Pacific Grove 15,528 15,530 15,550 15,057 15,036 Salinas 149, , , , ,359 Sand City ,498 1,498 1,498 Seaside 35,173 34,666 35,158 35,017 35,549 Soledad 27,365 28,853 33,760 38,801 41,405 Unincorporated 106, , , , ,052 County Total 422, , , , ,362 SANTA CRUZ COUNTY Capitola 9,918 10, ,090 11,269 Santa Cruz 56,421 58,919 63,265 65,884 67,807 Scotts Valley 11,565 11,923 12,311 12,688 12,921 Watsonville 49,571 51,903 56,544 61,245 62,463 Unincorporated 132, , , , ,162 County Total 260, , , , ,621 SAN BENITO COUNTY Hollister 37,002 40,415 49,064 59,259 62,756 San Juan Bautista 1,722 1,937 2,356 2,743 2,907 Unincorporated 18,600 20,079 24,720 27,429 29,068 County Total 57,324 62,431 76,140 89,431 94,731 BASIN TOTAL 740, , , , ,714 1 Association of Monterey Bay Area Governments, Adopted June 11, August 20, 2008 Revision Incorporation of Monterey Bay Area 2008 Regional Forecast

20 REFERENCES (1) 2005 Crop Reports, Monterey, Santa Cruz and San Benito Counties. (2) California Department of Finance Population Estimates, January August 20, 2008 Revision Incorporation of Monterey Bay Area 2008 Regional Forecast

21 This page is intentionally blank. 1-6 August 20, 2008 Revision Incorporation of Monterey Bay Area 2008 Regional Forecast

22 3.0 HEALTH AND ENVIRONMENTAL EFFECTS OF GROUND-LEVEL OZONE 3.1 INTRODUCTION The following information is based on knowledge developed by both EPA and the ARB in revising their respective ozone standards. This includes EPA's 1997 Ozone Fact Sheets, Ozone Staff Paper and Ozone Criteria Document prepared for EPA's update of the federal ozone standard and the ARB staff report prepared to support revision of the State ozone standard. 3.2 HEALTH EFFECTS When inhaled, ozone can impair normal functioning of the lungs in healthy people, as well as those with respiratory problems. When inhaled, even at very low levels, ozone can: cause chest pain and coughing; may also worsen asthma, bronchitis, and emphysema, as evidenced by studies showing increases in hospital admissions and emergency room visits for respiratory causes; cause acute respiratory problems; cause significant temporary decreases in lung capacity of 15 to over 20 percent in some healthy adults; cause inflammation of lung tissue; lead to hospital admissions and emergency room visits [10 to 20 percent of all summertime respiratory-related hospital visits in the northeastern U.S. are associated with ozone pollution]; and impair the body's immune system defenses, making people more susceptible to respiratory illnesses, including bronchitis and pneumonia. Children are most at risk from exposure to ozone: The average adult breathes 13,000 liters of air per day. Children breathe in 50 percent more air per pound of body weight than adults. 3-1

23 Because children's respiratory systems are still developing, they are more susceptible than adults to environmental threats. Ground-level ozone is a summertime problem. Children are outside playing and exercising during the summer months at summer camps, playgrounds, neighborhood parks and in backyards. Asthmatics and Asthmatic Children: Ozone can aggravate asthma, causing more asthma attacks, increased use of medication, more medical treatment and more visits to hospital emergency clinics. Asthma is a growing threat to children and adults. Children make up 25 percent of the population and comprise 40 percent of the asthma cases. Fourteen Americans die every day from asthma, a rate three times greater than just 20 years ago. For asthmatics having an attack, the pathways of the lungs become so narrow that breathing becomes akin to sucking a thick milk shake through a straw. Healthy Adults: Moderately exercising healthy adults can experience 15 to over 20 percent reductions in lung function from exposure to low levels of ozone over several hours. Damage to lung tissue may be caused by repeated exposures to ozone -- something like repeated sunburns of the lungs -- and this could result in a reduced quality of life as people age. Results of animal studies indicate that repeated exposure to high levels of ozone for several months or more can produce permanent structural damage in the lungs. Among those most at risk to ozone are people who are outdoors and moderately exercising during the summer months. This includes construction workers and other outdoor workers. 3.3 THE CHILDREN S HEALTH STUDY The Children s Health Study, which began in 1992, is a large, long-term, study of the health effects of children s chronic exposures to southern California air pollution. About 5,500 children in twelve communities have been enrolled in the study; two-thirds of them were enrolled as fourth-graders. Data on the children s health, their exposures to air pollution, and many factors that affect their responses to air pollution are gathered annually until they graduate from high school. The Children s Health Study was one of the primary references used to justify strengthening the California ozone standard. 3-2

24 The twelve communities in the study were chosen because they have different patterns of high and low levels of these four pollutants: Ozone Nitrogen dioxide Acid Vapor Particulate matter that is breathed deep into the lungs Concentrations of the four pollutants have been continuously measured in each community throughout the study and for brief periods in schools and some homes. In addition, each child s lung function is tested every spring. Annual questionnaires ask about the children s respiratory symptoms and diseases, such as chronic cough and asthma; level of physical activity; time spent outdoors; and many other factors known to influence children s responses to air pollution, such as parental smoking and mold and pets in the household. Major Results of the Study: Children living in high ozone communities, who actively participate in several sports, are more likely to develop asthma than children in these communities not participating in sports. Children living in communities with higher concentrations of nitrogen dioxide, particulate matter, and acid vapor have lungs that develop and grow more slowly and are less able to move air through them. This decreased lung development may have permanent adverse effects in adulthood Children who moved away from study communities had increased lung development if the new communities had lower particulate pollution, and had decreased lung development if the new communities had higher particulate pollution. Days with higher ozone concentrations resulted in significantly higher school absences due to respiratory illness. Children with asthma who are exposed to higher concentrations of particles are much more likely to develop bronchitis. 3-3

25 3.4 ENVIRONMENTAL EFFECTS Ozone has the following effects on vegetation: Ground-level ozone interferes with the ability of plants to produce and store food (e.g., starches), so that growth, reproduction and overall plant health are compromised. By weakening sensitive vegetation, ozone makes plants more susceptible to disease, pests, and environmental stresses. Ground-level ozone has been shown to reduce agricultural yields for many crops (e.g., soybeans, kidney beans, wheat, cotton) as well as damaging the quality of some crops, reducing their market value. The effects of ground-level ozone on long-lived species such as trees are believed to add up over many years so that whole forests or ecosystems can be affected. For example, ozone can adversely impact ecological functions such as water movement, mineral nutrient cycling, and habitats for various animal and plant species, and the type of trees that make up a forest may change from those that are sensitive to ozone to more tolerant varieties. Ground-level ozone can kill or damage leaves so that they fall off the plants too soon or become spotted or brown. These effects can significantly decrease the natural beauty of an area, such as in national parks and recreation areas. One of the key components of ozone, nitrogen oxides, contributes to fish kills and algae blooms in sensitive waterways, such as the Chesapeake Bay. 3.5 HEALTH BENEFITS OF REVISED STANDARD ARB estimated that attainment of the revised ozone standard would avoid a number of significant adverse health effects each year including: 580 premature deaths each year. 3,800 hospitalizations due to respiratory diseases for all ages. 600 emergency room visits for asthma for children under 18 year of age. 3.3 million school absences for children 5 to 17 years of age. 2.8 million minor restricted activity days for adults above 18 years of age. 3-4

26 REFERENCES 1. Health and Environmental Effects of Ground-Level Ozone, Fact Sheet, United Stated Environmental Protection Agency, Office of Air & Radiation and Office of Air Quality Planning & Standards, July 17, Fact Sheet, The Children s Health Study, Air Resources Board, February Review of the California Ambient Air Quality Standard for Ozone, Air Resources Board Staff Report, March 11,

27 This page is intentionally blank. 3-6

28 2.0 AMBIENT AIR QUALITY 2.1 AMBIENT AIR QUALITY STANDARDS Ambient air quality standards (AAQS) are set to establish levels of air quality that must be maintained to protect the public from the adverse effects of air pollution. State standards are established to protect public health, including the most sensitive members of the population. National standards include a primary standard to protect public health and a secondary standard to protect the public welfare including property, vegetation and visibility. However, the numerical values for primary and secondary standards are the same. Current State and National AAQS are shown in Table 2-1. Section 39607(e) of the California Health and Safety Code requires the Air Resources Board (ARB) to set State standards while the Federal Clean Air Act requires the U.S. Environmental Protection Agency (U.S. EPA) to set National standards. State and federal standards are updated periodically based on scientific studies and research on the effects of air pollution on health, vegetation and materials. State standards are generally more protective (stringent) than National standards. AAQSs are set for what are called criteria air pollutants, which include ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, PM 10 and PM 2.5. This plan pertains to the State AAQS for ozone. Ozone, the primary constituent of smog, is formed in the atmosphere through complex chemical reactions involving volatile organic compounds (VOC) and nitrogen oxides (NO x ) in the presence of sunlight. The primary sources of VOC within the planning area are on- and offroad motor vehicles, cleaning and surface coatings, solvent evaporation, landfills, petroleum production and marketing, and prescribed burning. The primary sources of NO x are on- and offroad motor vehicles, stationary source fuel combustion, and industrial processes. In 1997, a federal 8-hour ozone standard of 0.08 ppm was adopted by EPA. This standard replaced the prior federal 1-hour standard. In 2004, the NCCAB was designated as an attainment area for the federal 8 hour standard with an obligation to develop a maintenance plan. Maintenance of the federal standard is addressed in the District s 2007 Federal Maintenance Plan for the Monterey Bay Region, which was adopted in March of In 2006, the ARB revised the State AAQS for ozone to include an eight-hour average of ppm, while retaining the existing one-hour standard at 0.09 ppm. This standard is more stringent than the federal standard both in terms of concentration and the level of precision. Both the one and eight-hour components of the State standard must be met in order for the standard to be achieved. The NCCAB is a nonattainment area for the State standard. 2-1

29 TABLE 2-1 AMBIENT AIR QUALITY STANDARDS a Pollutant California Standards b National Standards c Averaging Primary d Secondary Time e ppm µg/m 3 ppm µg/m 3 ppm µg/m 3 1 hour None f None Ozone 0.08 g hours h Carbon Monoxide 8 hours , , ,000 1 hour 20 23, , ,000 Nitrogen Dioxide i Annual hour Sulfur Dioxide Annual hours hours 0.5 1,300 Respirable Particulate Matter 1 hour Annual (PM 10 ) j 24 hours Fine Particulate Annual Matter (PM 2.5 ) l 24 hours Calendar Lead quarter day avg 1.5 Sulfate 24 hours 25 Hydrogen Sulfide 1 hour Vinyl Chloride 24 hours Visibility Reducing Particles 8 hours (10 a.m.- 6 p.m.) In sufficient amounts to reduce prevailing visibility to < 10 miles when relative humidity of < 70% with equivalent instrument method a Standards first promulgated in ppm concentrations except where noted. Equivalent µg/m 3 concentrations based on reference temperature of 25 o C and reference pressure of 760 mm of mercury. b California standards for ozone, carbon monoxide (except Lake Tahoe), sulfur dioxide, nitrogen dioxide, PM 10, and visibility reducing particles are values not to be exceeded. c National standards, other than ozone and those based on annual averages, are not to be exceeded more than once a year. d Designed to protect human health with an adequate margin of safety e Designed to protect public welfare (i.e., prevent damage to vegetation, property, visibility) f On June 15, 2005, EPA revoked the 1-hour standard in the NCCAB. g 1997 Standard The standard and related implementation rules remain in place during transition to the hour ozone standard. h 2008 Standard - Adopted March 12, i On February 22, 2007, the Air Resources Board approved staff recommendations to amend the State nitrogen dioxide standard. j PM 10 refers to respirable particulate matter less than 10 microns in size. l PM 2.5 refers to respirable particulate matter less than 2.5 microns in size. 2-2

30 The 8-hour standard is more protective of public health than both the prior 1-hour standard and the National 8-hour standard. With natural background representing about half the level of the stringent 8-hour ozone standard, the introduction of the 8-hour average significantly increases the number of exceedances recorded at the District s monitoring stations and will make achieving the State AQQS much more difficult. This plan is the first to address this significant change to the State ozone standard. PM 10 and PM 2.5 are respirable particulate matter less than 10 and 2.5 microns in size. Because of their small size, they can be inhaled deep into the lungs and are therefore a health concern. They are classified as primary or secondary depending on their origin. Primary particles are unchanged after being directly emitted. Major sources of primary particles include fugitive dust from roads and agricultural operations. Secondary particulates are formed in the atmosphere largely by chemical reactions involving gases, e.g., sulfate from directly emitted sulfur oxides. Natural sources of particulates include sea spray, forest fires, volcanic debris, etc. Man-made sources include fuel combustion, industrial processes and transportation. The NCCAB does not meet the State PM 10 standard although it does meet all other State and federal AAQS for particulate matter. Attainment of State PM 10 standard is addressed in the District's 2005 Senate Bill 656 Implementation Plan for the Monterey Bay Region. 2.2 AMBIENT AIR MONITORING NETWORK As shown in Figure 2-1, ambient air quality is currently monitored at nine stations in the NCCAB. The network includes seven stations operated by the District, one station operated by the National Park Service at the Pinnacles National Monument (Pinnacles) and one station operated by an industry group in King City. The King City station, which was originally located on the perimeter of the city, was relocated closer to the center of the city in In order for the monitoring data to qualify as official Data for Record for comparison with the AAQS, the monitoring must follow strict guidelines established by the U.S. EPA and the California ARB. These guidelines assure that the data are accurate, consistent and representative of the area. The methods used in the monitoring must be considered either reference or equivalent by both the U.S. EPA and the ARB. Only Data for Record collected using these methods can be used to designate an area s air quality in relation to the ambient air quality standards. The monitoring stations operated by the District at Salinas, Hollister, Santa Cruz, Watsonville, Scotts Valley and Carmel Valley are part of the State and Local Air Monitoring System, or SLAMS network. These stations provide information on local and regional scale air quality. The stations operated at Davenport, King City and Pinnacles are referred to as Special Purpose sites because they provide information on the impact of specific sources, or to gauge air quality impacts on national resources, such as the National Parks. In the California Clean Air Act, the year 1987 is an initial reference year for gauging progress toward meeting the State AAQS for ozone. Most stations have historical records that date back to 1987 or earlier. 2-3

31 FIGURE

32 2.3 AREA DESIGNATIONS AND ATTAINMENT STATUS Designations in relation to the State standards are made by the ARB while designations in relation to the National standards are made by EPA. State designations are updated annually while the National designations are updated when either the standards change, or when an area requests that they be re-designated due to changes in the area s air quality. Designations are made by air basin and in some cases, designations are made at the county level. Designations are made by pollutant according to the following categories: Attainment Air quality in the area meets the standard. Nonattainment Transitional Air quality is approaching the standard (State only). Nonattainment Air quality in the area fails to the applicable standard. Unclassified Insufficient data to designate area, or designations have yet to be made. Nonattainment designations are of most concern because they indicate that unhealthy levels of the pollutant exist in the area, which typically triggers a need to develop a plan to achieve the applicable standard. State and National designations are shown in Table 2-2. TABLE 2-2 ATTAINMENT STATUS FOR THE NORTH CENTRAL COAST AIR BASIN Pollutant State Federal Ozone (O 3 ) Nonattainment 2) Attainment Inhalable Particulates (PM 10 ) Nonattainment Attainment Fine Particulates (PM 2.5 ) Attainment Unclassified/Attainment 1) Carbon Monoxide (CO) Monterey Co. Attainment San Benito Co. Unclassified Attainment Santa Cruz Co. - Unclassified Nitrogen Dioxide (NO 2 ) Attainment Attainment Sulfur Dioxide (SO 2 ) Attainment Attainment Lead Attainment Attainment Notes: 1) In 2006, 5he Federal 24-hour standard for PM 2.5 was revised from 65 to 35 µg/m 3. Although new designations have yet to be made, it is expected that the NCCAB will be designated attainment. 2) Effective July 26, 2007, the ARB designated the NCCAB a nonattainment area for the State ozone standard. 3) Nonattainment pollutants are highlighted in Bold. 2.4 AMBIENT AIR QUALITY AIR BASIN EXCEEDANCE TREND The long-term ( ) trend in exceedances of both the 1 and 8 hour components of the State AAQS is shown in Figure 2-2. Although the figure indicates an overall improvement in air quality, it also demonstrates how the introduction of the 8-hour standard greatly increases the number of exceedances compared to the 1-hour criteria. Although the year-to-year 1 and 8- hour exceedance patterns track similarly, overall, the 8-hour criteria increases the number of annual exceedances 5 to 10 fold, depending on the year. 2-5

33 Years that would have previously been regarded as "clean" according to the 1 hour criteria often feature numerous exceedances of the 8 hour criteria. For instance, in 2004 for the first time, there were no exceedances of the 1-hour criteria recorded in the NCCAB. However, there were still 13 exceedance days for the 8-hour criteria during that same year. The figure also shows an overall declining trend in exceedances, although there can be considerable year to-year variation, particularly for 8-hour exceedances. The year-to-year variations tend to be driven by year-to-year variations in weather, while the overall decline tends to be driven by a reduction in emissions across the region. The majority of the exceedance days (<80% based on 2003 to 2005 data) occur at Pinnacles. For comparison, exceedance days for the National 8-hour ozone standard are included in Figure 2-2. This follows a similar pattern to the State exceedance days, although the number of exceedances is less than both the 1 and 8 hour criteria of the State AAQS. The NCCAB has achieved the National Standard due to the improvement in air quality shown in the figure. Exceedance Days Figure 2-2 NCCAB Exceedance Days 1988 to State 8-Hr State 1-Hr Nat'l 8-Hr SEASONAL EXCEEDANCE PATTERN Ozone is formed by a photochemical reaction between volatile organic compounds and the oxides of nitrogen in the presence of sunlight. Consequently, ozone tends to be seasonal pollutant which develops primarily in the summertime when the sunlight is strongest. Statewide, the ozone season is considered the months May through October. Figure 2-3 shows the 10-year average seasonal distribution of exceedances for both the 1 and 8-hour components of the standard. 2-6

34 5 Figure 2-3 Seasonal Distribution 1 and 8-Hr Exceedances Exceedance Days Apr May Jun Jul Aug Sep Oct 8-hr Exceedances (10 yr Average, Pinnacles) 1-Hr Exceedances (10 yr Average, NCCAB) As shown in the figure, most NCCAB exceedances follow the typical May Through October pattern. However, with the introduction of the tight 8-hour standard, exceedances become much more frequent and start as early as April. The peak month for exceedances of both the 1 and 8-hour criteria is August. However, the 8-hour distribution has a significant secondary peak in May, when there are typically no 1-hour exceedances. Exceedances of the 8 hour standard remain high during September, a month when the 1 hour standard is not exceeded for most years. Overall, monthly exceedances of the 8-hour criteria are five to ten times more frequent than the 1-hour criteria. Thus, while the seasonal exceedance patterns for both the 1 and 8-hour criteria are similar, the 8-hour standard greatly increases the number of exceedances and causes the ozone season to start earlier ARB AIR QUALITY INDICATORS The California Clean Air Act (CCAA) requires the ARB to evaluate and identify air quality indicators that can be used to by districts to assess their progress toward attainment of the State standards [HSC section 39607(f)]. An indicator is a way of summarizing measured air quality data so as to represent certain aspects of air quality in a specific area. Progress is assessed triennially. The assessment is to address (1) the peak concentrations in the peak "hot spot" subarea, (2) the population-weighted average of the total exposure, and (3) the areaweighted average of the total exposure (ARB Resolution 90-96, November 8, 1990). This section presents the trends assessments for the three air quality indicators. The trends extend back to 1987 which is the initial reference year for gauging progress in achieving the standard. ARB's description of the air quality indicators is presented in Appendix B. It 2-7

35 should be noted that complete indicator data for both the 1 and 8-hour components of the standard were not available at the time of this writing. Consequently, the assessment for the peak hot spot area is based on indicators for both the 1 and 8-hour components of the standard. The assessments for population and area exposure indicators are based only on the 1-hour component of the standard (1) - Peak Concentration or "Hot Spot" Indicator The "hot spot" indicator is assessed in terms of what is called the Expected Peak Day Concentration or EPDC. The EPDC is calculated by ARB based on ambient data from each site in the air basin. The EPDC is the calculated peak one hour concentration, in parts per million (ppm), that is statistically expected to occur only once per year. The calculation procedure uses air monitoring data from each site during a consecutive three-year period. Three years of data are used to provide a more stable indicator than would be produced by just one year of data, since air quality trends can be highly affected by year to year variations caused by the weather. The EPDC "hot spot" indicator is the most important of the three indicators because it is used by ARB to designate areas in relation to the ambient air quality standard. EPDCs are updated annually, with the most recent 8-hour EPDC indicators being for the year 2005, based on data from 2003 to The ARB recommends that districts use the 3-year EPDC indicator for trends analysis since this is the key statistic used by the ARB in determining an area's attainment status. Pinnacles is the NCCAB's peak "hot spot" station. The NCCAB's attainment status is closely linked to conditions monitored at this site. The majority of all NCCAB exceedances occur at this remote location, which is far from urban sources of pollution. Figures 2-4a and 2-4b shows the trend in 1 and 8-hour EPDCs for this site, respectively. Note that the ppm concentration axis for each figure are truncated above zero in order to enhance the trends. Figure 2-4a ppm Pinnacles NM - NCCAB "Hot Spot" 1-Hour Standard

36 Figure 2-4a shows that overall there was a 35% improvement in the Pinnacles 1-hour EPDC indicator between 1987 and 2006, with the indicator decreasing from to ppm. This long-term improvement is due to regional emission reductions. The trend can be divided into two sub-trends. During the early years improvement was rather dramatic with nearly three quarters of the overall improvement occurring during the years 1987 to This corresponded to a period of relatively rapid decreases in emissions of ozone precursors from regional sources. However, between 1995 and 2006, as new emission reductions from mobile and stationary sources became relatively smaller, the improvement becomes flatter at 11%. Despite the reduced rate of progress, it is significant to note that Figure 2-4a shows that the 1-hour EPDC for actually falls within the level of the 1-hour standard. Thus, without the addition of an 8-hour standard, the NCCAB could have reached the milestone of achieving the State AAQS for ozone. Remaining within the 1-hour component of the standard will likely be short lived as the three year period includes 2004, a landmark year when there were no exceedances of the State AAQS recorded in the entire NCCAB. Year to year variations in the 1-hour indicator caused by the weather will likely cause the indicator to fluctuate above and below the standard until regional emission reductions are sufficient to override this natural influence. Eight hour EPDCs for the Pinnacles Hot Spot are shown in Figure 2-4b for the years (8-hour values for 2006 were not available as of the time of this writing). The pattern of progress is similar to that of the 1-hour indictor. Overall, there was a 42% improvement in the 8-hour indicator between 1987 and 2005 with the majority of the improvement occurring during the early years when there were an abundance of emission reductions occurring in the region. Again, progress slows during the period 1995 to 2005 when regional emission reductions became more scarce. Although significant progress has been made toward achieving the 8-hour standard, the 8-hour indicator remained nearly 20% over the standard in Figure 2-4b NCCAB 8-Hour EPDC Pinnacles NM - NCCAB "Hot Spot" ppm Hour Standard

37 2.4.3(2) Overview of ARB Exposure Indicators The ARB develops two annual exposure indicators for each air basin in the State. The indicators describe the exposure of both the population and the land surface area to ozone levels exceeding the AAQS. The indicators are weighted according to the population and area within each census tract in the air basin and the tract's proximity to monitoring stations recording ozone levels above the 1-hour standard. The population weighted exposure indicator is in ppm-hours above the standard per person, while the area weighted exposure indicator is in ppm-hours above the standard per square kilometer. The current exposure indicators relate to only to exceedances of the 1-hour standard and are not yet available for the 8-hour. Although there are no exposure based standards for these indicators, they provide a more complete picture of progress being made toward achieving the standard than can be assessed by evaluating progress at a single station alone. Exposure indicators show higher year-to-year variation than the peak "hot spot" indicator because they are based on one year of data rather than three years of data which are smoothed to develop the peak indicator (3) - Population Exposure Indicator Figure 2-4 shows the trend in the NCCAB population indicator. The figure shows a beneficial downward trend in population exposure. This has occurred despite the population increasing more than 20% between 1990 and 2005, as well as annual variations in the indicator caused by the weather. This suggests that emission controls have offset population growth, resulting in a net improvement in the air quality indicator. Regional reductions in ozone precursors have reduced both the severity and duration of episodes when the ozone standard is exceeded which is reflected in the downward trend of the indicator. Figure 2-5 POPULATION WEIGHTED 1-HR EXPOSURE INDICATOR (ppm-hrs above 1-hr standard/person) ppm-hrs above standard/person

38 The decrease in the population exposure indicator is also due to the dwindling number of exceedances of the 1-hour State AAQS that occur in populated areas. Most exceedances occur at Pinnacles NM, which is a remote area having sparse population and little contribution to the population indicator. The population indicator drops to near zero for the years because of the combined influence of improving air quality and the fact that most of the remaining exceedances occur in a sparsely populated area (4) - Area Exposure Indicator The trend for the area exposure indicator is shown in Figure 2-5. Like the population indicator, the area indicator also shows significant progress since There are two main reasons for this. First, with the decline in peak monitored levels of ozone, the severity (ppm above standard) of exceedances has decreased. Second, the annual number of hours above the standard has also diminished. In fact, the indicator drops very close to zero in 2004 and 2005 because there were only three hours of marginal exceedances recorded during those years. The area indicator shows slightly better improvement than the population indicator, because unlike population which has been increasing, the area within each census tract remains constant. Figure 2-6 AREA WEIGHTED 1-HR EXPOSURE INDICATOR (ppm-hrs above 1-hr standard/sq km) ppm-hrs above standard/sq km Natural year-to-year variation caused by the weather can also be seen in both Figure 2-4 and Figure 2-5. For instance, strong high pressure systems were present during the years 1996, 1998 and 2002 resulting in air stagnation and poor air quality, while the relatively clean El Nino year 1997 featured values near zero because of favorable ventilation. These year-to-year variations become more important as the air basin approaches the standard. The area-wide exposure indicator applies to the land surface of the entire air basin, which is largely covered by vegetation. Healthy vegetation removes carbon dioxide from the atmosphere. Therefore, the progress shown for the area-wide exposure indicator should also be beneficial in limiting greenhouse gases. 2-11

39 2.4.4 TRENDS AT INDIVIDUAL STATIONS Current 1 and 8-hour EPDCs for all District stations, and whether or not they are within the standard, are summarized in Table 2-3. TABLE 2-3 PEAK DAY CONCENTRATIONS BY STATION Station 8-Hour 1) EPDC (ppm) Meets Met? 1-Hour 2) Met? Entire Standard? 3) Pinnacles/NCCAB No ) Yes No Hollister No Yes No Scotts Valley No Yes No Carmel Valley Yes Yes Yes King City Yes Yes Yes Santa Cruz Yes Yes Yes Watsonville Yes Yes Yes Salinas Yes Yes Yes Davenport Yes Yes Yes Notes: 1) 8-Hour EPDCs based on Data for Record for the years ) 1-Hour EPDCs based on Data for Record for the years ) The California standard is exceeded when either the 1-hour average equals or exceeds ppm, or the 8-hour average equals or exceeds ppm. Both components of the standard must be meant in order for the standard to be upheld. Stations and EPDCs exceeding the standard are highlighted in bold. 4) The hour EPDC for Pinnacles meets the 1-hour standard. 5) EPDC - Expected Peak Day Concentration, which is the statistically calculated peak concentration expected to occur once per year, based on the latest three years of data. As shown in Table 2-4, all stations currently meet the 1-hour criteria of the standard. However, with the introduction of the 8-hour criteria, three stations now fail to meet the State ozone standard. These are Pinnacles, Hollister and Scotts Valley with Carmel Valley only meeting the standard by a thin margin. This is similar to the situation about 15 years ago with the 1-hour standard where these same three stations failed to meet the standard with Carmel Valley occasionally exceeded the standard. The 8-hour EPDC for Pinnacles, the NCCAB s design station for the State standard, is the worst in the area and is nearly 20% over the standard, while Scotts Valley and Hollister are 5 and 10% over the standard, respectively. In contrast, several stations have 1 and 8-hour EPDCs well within the standard. These include Santa Cruz, Watsonville, Salinas and Davenport. The EPDC for Salinas, the area s most populated site, is one of the lowest in the entire air basin. The NCCAB will achieve the State standard when the 1 and 8-hour EPDCs for all network stations are within the standard. It should be noted that not all recorded levels of ozone which exceed the standard are considered violations of the standard. Based on criteria developed by ARB, exceedances that are higher than the station specific EPDC are not considered violations but rather infrequent extreme concentration events that are excluded from regulatory consideration. Additionally, exceedances which are known to have been caused by 2-12

40 rogue events, such as stratospheric ozone intrusion or forest fires, are excluded from regulatory consideration. Table 2-3 also illustrates a well defined difference between the coastal and inland sites, whereby the inland sites have higher EPDCs. This is because coastal areas typically benefit from the ventilation provided by cool coastal sea breezes, while the inland sites, which are further removed from marine influence, tend to experience pollution build-up from local and transported emissions. Additionally, warmer temperatures inland contribute to the formation of ozone. Figure 2-6 shows nine charts with long-term trends for the 1 and 8 hour EPDCs for each station in the NCCAB s network. The figure shows that while Carmel Valley and King City have been in compliance with the 1-hour standard for at least 10 years, they have only recently achieved the 8 hour standard. In contrast, Santa Cruz, Watsonville, Salinas and Davenport have been in compliance with both components of the standard for at least ten years. These stations are least likely to fall back into non-compliance. However, stations with a recent history of noncompliance, and EPDCs close to the standard, such as Carmel Valley and King City are at most risk of falling back into noncompliance due to variations caused by the weather. Improvement in the 8-hour EPDC has been slower at the NCCAB s population sites that fail to meet the standard than at Pinnacles. During the period of common record between , the 8-hour EPDC at Pinnacles decreased 13% while the indictor for Scotts Valley and Hollister improved only 6 and 9%, respectively. Incremental improvement tends to be slower for stations closer to the standard. 2.5 TRANSPORT In addition to emissions generated locally within the NCCAB, ARB has determined that emissions transported into the NCCAB from areas outside the air basin can have a significant impact on measured violations of the State AAQS for ozone. This is particularly true at stations that currently do not meet the State standard, including Pinnacles, which is the air basin's design site for meeting the State AAQS, as well as Hollister and Scotts Valley. These assessments were for discrete peak 1-hour exceedance events related to the 1- hour standard. Although the ARB transport assessments have yet to be updated to reflect 8- hour exceedance events, the subject is discussed in greater detail in Chapter 5 based on what has been learned previously based on the 1-hour standard

41 Figure AND 8-HOUR EXPECTED PEAK DAY OZONE CONCENTRATIONS Pinnacles NM (NCCAB Designation Site) ppm Hr EPDC 8-Hr EPDC Hollister ppm Hr EPDC 8-Hr EPDC Scotts Valley ppm Hr EPDC 8-Hr EPDC 2-14

42 Figure 2-7 (Continued) 1 AND 8-HOUR EXPECTED PEAK DAY OZONE CONCENTRATIONS Carmel Valley ppm Hr EPDC 8-Hr EPDC King City ppm Hr EPDC 8-Hr EPDC Watsonville ppm Hr EPDC 8-Hr EPDC 2-15

43 Figure 2-7 (Concluded) 1 AND 8-HOUR EXPECTED PEAK DAY OZONE CONCENTRATIONS Santa Cruz (Relocated 1996) ppm Hr EPDC 8-Hr EPDC Salinas (Relocated in 2000) ppm Hr EPDC 8-Hr EPDC Davenport ppm Hr EPDC 8-Hr EPDC 2-16

44 4.0 EMISSION INVENTORY AND FORECASTS 4.1 INTRODUCTION The emission inventory is an estimate of the amount of ozone precursors emitted into the air each day by man-made (anthropogenic) activities. The inventory presented in this plan represents emissions of VOCs and NOx (tons per day) on a typical weekday during the May through October ozone season. This inventory is often referred to as a summer day planning inventory. Since ambient ozone levels depend largely on the amount of precursors emitted to the atmosphere, the trend in the planning inventory is used to assess the region s progress toward attaining the California ambient air quality standard. Consequently, the inventory is a key component in the development of plans and regulations adopted to reduce ozone. 4.2 STRUCTURE OF THE EMISSION INVENTORY The air basin anthropogenic inventory is basically a multi-level emissions accounting system. Its overall structure follows a four level hierarchy, with each successive level providing a greater level of detail. In the first or Division level, the inventory is divided into three major divisions; Stationary Sources, Area-wide Sources and Mobile Sources. The second level is the Major Source level, which sub-divides Stationary Sources into five categories, Area Sources into two categories and Mobile Sources into two categories. In the third level, each of the nine Major Source categories are further divided into anywhere from two to eighteen Summary level categories, with mobile sources having the greatest number of subcategories. The inventory presented in this chapter is resolved to the third or Summary level of the hierarchy. Beyond this exists a fourth level, which is the detailed or Emission Inventory Category (EIC) level, which further desegregates the Summary level categories into literally hundreds of smaller categories. Stationary sources include typically large facilities such as power plants or cement plants, while area-wide sources include an aggregate of individually smaller sources, which when grouped together have significant emissions such as consumer products or residential fuel consumption. Mobile sources consist of the numerous cars and trucks that travel the streets and highways of the NCCAB, as well as other mobile sources such as off-road agricultural and construction equipment, trains and aircraft. Emission inventories and inventory estimation methods are periodically updated to provide more accurate estimates and to better reflect current trends. These changes, along with the need to periodically reassess progress toward achieving the standard, are primary reasons for periodically updating the AQMP. In the sections that follow, the current inventory is discussed, 4-1

45 as well as significant changes to the emission estimates and activity data that are used to develop those estimates. Aside from the three major divisions of the anthropogenic inventory, a separate inventory estimates emissions from natural sources, such as vegetation. Emissions from natural sources are difficult to quantify with any degree of certainty. Since emissions from natural sources are beyond regulatory control, they are excluded from the anthropogenic inventory. 4.3 EMISSION FORECASTS Future emissions depend on the balance between growth and control. Growth factors are used to estimate forces which increase emissions, while control factors estimate the offsetting effect of emission controls. Growth factors depend on the forecast changes in activity indictors that reflect growth in a region, such as population, housing, employment, industrial output, vehicles miles traveled, number of vehicles, etc. These indicators are developed by State and local agencies, such as the Association of Monterey Bay Area Governments (AMBAG). Control factors reflect the effectiveness of various control measures, such as emission controls applied to industrial sources, vapor recovery systems used as gas stations, as well as cleaner burning engines and fuel. Control factors are the result of regulations developed by State, local and federal agencies. Each category in the inventory is linked to a particular activity indicator most representative of the category. For instance, for emissions associated with residential fuel consumption, the number of dwelling units is a reasonable surrogate for growth. Control factors are applied to specific categories in the inventory depending on what regulations affect that particular source. Emission forecasts for the Stationary and Area Source inventories are developed by applying applicable growth and control factors to each category of a reference or base year emission inventory to create a series of adjusted inventories which best reflect expected changes projected to specific years in the future. For this AQMP, 2002 was used as the base year. Growth and control factors were applied to the base year inventory to create inventories for the years 2007, 2010, 2015, 2020, 2025 and out to the forecast horizon of The projections are developed jointly by the ARB and the District. The California Emission Forecasting System (CEFS) is the computer tool used to develop the projections. The emission estimates are based on the most current growth and control data available at the time of the forecast runs. For mobile sources, CEFS integrates the emission estimates from ARB s EMFAC and OFFROAD mobile source emission models to provide a comprehensive anthropogenic emission inventory. The forecasts presented in this plan are based on Version 1.06 of this forecast system. As with any other type of forecast, inventory forecasts become less reliable the further they are projected into the future. This is due to the increased uncertainty in what the actual level of growth and control will be in the distant future. 4-2

46 4.4 EMISSION INVENTORY AND TRENDS The summary level emission inventory for the years 1990 to 2030 is presented in Table 4-1 for VOCs and Table 4-2 for NO x. A spreadsheet of the detailed EIC level inventory for stationary, area and other mobile sources is presented in Appendix A. As shown in the Tables 4-1 and 4-2, there has been a significant decline in the overall inventory since 1990, which is forecast to continue through the year The decrease in both VOCs and NOx corresponds to the general improvement in ambient ozone levels in the NCCAB described in the air quality section. The decrease is most pronounced for NOx, while the decrease in VOC s is not as rapid and flattens out after The 1990 to 2030 reduction in VOCs is expected to be about 53 tons per day or about a 46% reduction, while the corresponding reduction in NOx is expected to be about 78 tons per day for a 62% reduction. A photochemical modeling project undertaken by the District in the 1990's indicated that areas with the highest ozone readings, including Pinnacles National Monument, are most sensitive to regional reductions in the oxides of nitrogen. Thus, even though the decline in VOCs is less than NOx, the reduction in NO x should be beneficial in continuing the reduction in ambient ozone at the locations where ozone is highest. The 1990 to 2030 trends for the inventories presented in Tables 4-1 and 4-2 are graphically illustrated in Figure 4-1 for VOCs and Figure 4-2 for NOx. The figures show the overall decline in the emission of both ozone precursors. The decrease is most pronounced for NO x, which is forecast to be at half the 1990 levels by the year Major categories of the 2007 emission inventory, as well as the corresponding forecasts for the year 2020, are illustrated in Figures 4-3 & 4-4 for VOCs and 4-5 & 4-6 for NO x. The pie charts show that emissions from motor vehicles represent a significant but declining fraction of both the VOC and NO x inventories. By 2020, emissions from on-road vehicles are forecast to be less than half 2007 levels. The figures also indicate that VOCs from solvent use and NO x from stationary source fuel combustion in the Manufacturing and Industrial category represent increasing fractions of the VOC and NO x inventories, respectively Stationary Sources Tables 4-1 and 4-2 indicate that stationary sources represent about 13% and 25 % of the 2007 VOC and NOx inventories, respectively. The tables also indicate that between 2007 and 2020, stationary source emissions are forecast to increase 1.4 tons per day for VOCs and 3.3 tons per day for NO x. For VOCs, several categories contribute to the overall increase with the Cleaning & Surface Coating category the primary contributor. The larger increase for stationary source NO x is driven by a single large category related to natural gas combustion in the Manufacturing & Industrial sector. The influence of this single large subcategory on the overall growth of the stationary source NO x inventory is illustrated in Figure

47 Categories with projected emission increases are candidates for control measures, which will be described in greater detail later in the AQMP. Control of most large growth categories has already been undertaken during the planning process for the 1-hour standard. Availability of any remaining large growth categories is an important factor to consider when developing strategies to achieve the stringent 8-hour standard. It should be noted that the high projected size and rate of growth of the Manufacturing & Industrial category may be unrealistic and must be verified prior to implementing specific controls measures Area-wide Sources As shown in Tables 4-1 and 4-2, forecasted area-wide emissions are expected to increase, particularly for VOCs. This is primarily due to expected increases in prescribed burning by State, federal and private land managers who utilize prescribed burning for habitat management, wild fire prevention, ordnance removal, range improvement and forest management. These increases were previously accommodated in the 2000 AQMP based on a survey of major burners in the NCCAB. Consistent with land management goals at both the State and federal level, the survey found that at the local level, there are plans to substantially increase prescribed burning in the future. However, funding continues to be a constraint to the planned increases. Since the burning of vegetation produces large amounts of both VOC s and NO x, emission increases for both ozone precursors were estimated from the survey. Although the emissions for this large category are included on the ozone planning day inventory, it is not expected that emissions from prescribed fires will affect the area s attainment status. The District s Smoke Management Program (SMP) does not permit prescribed burning on days when ozone is expected to be high. Further, as mitigation in the SMP, the District coordinates burning activities during the ozone season to keep ozone precursor emissions (i.e. Daily Emissions Allocation provision) within the estimates of the AQMP. In addition, due to the large scale meteorological conditions that accompany high ozone days, most high ozone Days are declared No Burn Days. Consequently, high ozone days and days when prescribed burning is being conducted are generally not concurrent events. Starting with the 2000 AQMP, the ARB added a new Livestock Husbandry category to the area-wide inventory. This rather large no growth VOC category is to accommodate animal digestive processes Mobile Source Emissions The mobile source emission inventory includes exhaust and evaporative emissions from on-road motor vehicles as well as emissions from vehicles and mobile equipment that do not operate on roadways, such as tractors, construction and mining equipment, recreational vehicles as well as aircraft trains and marine vessels. Mobile Sources are divided into two major source categories: On-Road Motor Vehicles and Other Mobile Sources. Emission estimates for Mobile Sources are developed by the ARB using two rather complex estimation models; the EMFAC model for On-Road Motor Vehicles 4-4

48 and OFFROAD for Other Mobile Sources. Both models estimate summer seasonal daily emissions at the county level. ON-ROAD EMISSIONS (1) - On-Road Motor Vehicle Emission Model - EMFAC Model Estimates for emissions from all on-road motor vehicles are developed by the ARB s emission model called EMFAC. The EMFAC model estimates emissions from a wide variety of on-road motor vehicle types ranging from light duty passenger autos to heavy duty urban buses. This is a complex model which takes into account the composition and age of the vehicle fleet, adopted controls for motor vehicles as well as travel activity data from regional travel models. The current generation of this model is called EMFAC2007. The version used in this plan is EMFAC2007, Version (2) - On-Road Motor Vehicle Activity - AMBAG Travel Data The level of transportation activity by vehicles traveling on the region s various highways and byways is an important factor affecting the amount of emissions released to the air each day. The key indicators for travel activity in the area are developed by AMBAG s regional transportation model. These data are used in the EMFAC model to estimate daily emissions from the area s travel network, which includes the area s highways as well as local roads. The activity indicators developed by AMBAG include the number of daily Vehicle Miles Traveled (VMT) driven by all the vehicles in the area, the number of daily trips and vehicle speed distributions during the trips. Local travel data, as developed by the AMBAG model, are generally preferred to data developed at the State level because they reflect the local travel network more completely than the statewide network available through CALTRANS. The travel data used by EMFAC2007 for this plan are from AMBAG s June 2005 Metropolitan Transportation Plan, which is the most recent data available (3) - Emissions from On-Road Motor Vehicles Estimates for emissions from on-road motor vehicles from EMFAC2007 for are shown in Figure 4-7. The figure shows a significant decline in emissions from on-road sources for both VOCs and NOx. VOC and NO x diminish from being dominant categories in the overall inventory in 1990 to a relatively small part of the inventory by The decrease in emissions from on-road motor vehicles is a major contributor to the overall improvement in regional ozone levels over the last decade. Emissions by vehicle class are shown in Tables 4-1 and 4-2. Emissions from light duty autos are the principle contributor to the VOC inventory for on-road motor vehicles. Emissions from both light duty autos and heavy duty diesel trucks are the principle contributors to NOx. 4-5

49 Additional details of motor vehicle activity and emissions by vehicle class, year and county, are provided in Appendix B. Figure 4-8 illustrates an important relationship between growth and control for on-road motor vehicles. The figure demonstrates that despite significant growth in VMT, overall emissions have declined due to the offsetting effect of emission controls on motor vehicles. This relationship is one of the key factors contributing to the improvement in air quality region-wide. Without controls on motor vehicles, the regions motor vehicles would essentially be a fleet of gross polluters and the inventory would increase according the growth in VMT, leading to significant air quality degradation. OTHER MOBILE SOURCES 4.4.3(4) Other Mobile Sources OFFROAD Model Emission estimates from a large spectrum of off-road equipment are developed by the ARB s emission model called OFFROAD. These include aircraft, trains, ships & commercial boats, recreational boats, off-road recreational vehicles, off-road equipment, farm equipment and fuel storage. OFFROAD uses information related to equipment population, activity, engine specific emissions and applicable control factors to estimate emissions. The version of the model used in this plan is OFFROAD2007. Similar to the on-road model, OFFROAD2007 estimates average seasonal daily emissions for each county in the state and also develops forecasts based on anticipated growth and controls within each equipment category. Many of the source categories involve heavy duty diesel engines that are used to power various equipment such as agricultural tractors, pumps and sprayers, as well as construction and mining equipment. Figure 4-9 illustrates the trend in Other Mobile emissions as developed by OFFROAD2007. The figure shows a significant decline for both VOCs and NOx. Between 2007 and 2020, VOCs are projected to decrease by 3.9 tons per day for a 31% decrease, while NOx emissions are expected to decrease by 6.6 tons per day for a 43% decrease. As shown for Other Mobile Sources in Table 4-1, the largest decreases in VOCs are expected for Recreational Boats and Off-Road Equipment. Table 4-2 indicates that the largest decrease in NOx is from Off-Road Equipment and Farm Equipment. These reductions are due to the introduction of cleaner fuels and the use of improved control technologies Natural Sources Aside from emissions caused by human activity, emissions from natural sources also contribute to the formation of ozone. VOCs are the larger part of the natural inventory with emissions from vegetation foliage (i.e. biogenic sources) the primary contributor. For NOx, natural emissions come from wildfires as well as microbial activity in the soil. Natural emissions are difficult to quantify and are highly dependant on ambient temperature, sunlight and moisture. Natural emissions vary greatly season to season and year to year. In general, natural emissions are highest during the ozone season. 4-6

50 Rough estimates of NCCAB VOC emissions are in the range of 100 to 125 tons per day. The majority of these are thought to be produced in Monterey County s oak woodlands and coastal chaparral environments. Rough estimates of NOx are in the range of 1 to 5 tons per day, and are highest during wildfire events. The actual impact of biogenic emissions on air quality is uncertain. The role of VOCs in ozone formation is not just dependant on the overall quantity of emissions, but also the reactivity of the specific compounds, their spatial distribution, and the ratio between VOCs and NOx. Since biogenic VOCs are emitted over large areas of natural vegetation where ozone is typically low, and many of the VOC species emitted are only moderately reactive, their impact on air quality is likely less than an equivalent amount of anthropogenic emissions, which tend to occur in concentrated urban areas and feature more reactive species. Although natural emissions are highly uncertain and are beyond regulatory control, they do contribute to the ambient background level of ozone, which is estimated to be about 0.03 ppm or nearly half the level of the 8-hour standard. Since controls can only be applied to the increment above background, natural background becomes increasingly important when developing strategies to achieve the State 8-hour standard. Methods for improving our understanding of the role of natural emissions are the subject of on-going scientific research. 4.5 POPULATION TRENDS AND EMISSIONS The size and growth of the region s population are important factors affecting the quantity of emissions emitted in the area. Figure 4-11 compares the current AMBAG population forecasts to the year 2030 with the regional emission forecasts out to that same year. The chart indicates that despite a significant overall increase in population of over 360,000 persons (59% increase) between 1990 and 2030, emissions are expected to decrease by over 130 tons/day (55% decrease). This demonstrates another major success for regional control strategies in that despite a significant increase in population, emissions are expected to decline significantly. This is largely due to reductions in tail-pipe emissions from motor vehicles as well as the application of clean air technologies on power plants. 4.6 EFFECT OF DISTRICT RULES ON EMISSIONS The District has adopted a number of rules affecting both stationary and area-wide sources of emissions for the purpose of achieving the State and federal AAQS for ozone. These rules are summarized in Table 4-3. The emission reductions associated with each of these rules depends to on the size of the emission category affected by the rule and the effectiveness of the controls. Examples of two rules which have had a relatively large impact on the inventory are Rule 431, which is a NO x reduction measure for electric utility boilers, and Rule 425, which is a formulation measure affecting VOC s from the use of cutback asphalt. 4-7

51 The impact of each of these rules on emissions is shown in Figure As shown in the figure, Rule 431 resulted in a ten fold reduction in emissions from electric utility boilers. This single rule reduced the entire NCCAB NOx inventory by over 15%. The reductions are greatest when electric power demand on the grid is greatest, which is typically on hot summer days when ozone is highest. The cutback asphalt rule reduced asphalt related VOC s by over 50%. The four ton per day reduction has made a significant contribution to the overall decline in regional VOC emissions. Although measures like these have contributed to achieving the State 1-hour standard and have contributed to progress toward achieving the State 8-hour standard, additional controls may be necessary to expedite achieving the stringent 8-hour standard. 4-8

52 TABLE 4-1 EMISSION INVENTORY & FORECASTS FOR VOLATILE ORGANIC COMPOUNDS FOR NORTH CENTRAL COAST AIR BASIN Ozone Seasonal Planning Inventory (Tons/Day) VOC SOURCE CATEGORY STATIONARY SOURCES: Fuel Combustion Electric Utilities Cogeneration Oil and Gas Production Manufacturing and Industrial Food and Agricultural Processing Service and Commercial Other TOTAL - Fuel Combustion Waste Disposal Landfills TOTAL Cleaning & Surface Coatings Laundering Degreasing Coatings & Process Solvents Printing Adhesives & Sealants Other TOTAL - Cleaning & Sfc Coatings Petro Production & Marketing Oil and Gas Production Petroleum Marketing Other TOTAL - Petro Prod. & Marketing Industrial Processes Chemical

53 VOC SOURCE CATEGORY Food and Agriculture Mineral Processes Electronics Other TOTAL - Industrial Processes Use of Banked Emissions TOTAL TOTAL STATIONARY SOURCES AREA-WIDE SOURCES: Solvent Evaporation Consumer Products Architectural Coatings Non-Methyl Bromide Pesticides Asphalt Paving/Roofing TOTAL - Solvent Evaporation Miscellaneous Processes Residential Fuel Combustion Livestock Husbandry Structural & Auto Fires Prescribed Burns Cooking TOTAL - Miscellaneous TOTAL AREA-WIDE SOURCES MOBILE SOURCES: On-Road Motor Vehicles (EMFAC2007) Light Duty Passenger Light Duty Trucks (LDT1) Light Duty Trucks (LDT2) Medium Duty Trucks Light Heavy Duty Gas Trucks (LHDV1) Light Heavy Duty Gas Trucks (LHDV2)

54 VOC SOURCE CATEGORY Medium Heavy Duty Gas Trucks Heavy Heavy Duty Gas Trucks Light Heavy Duty Diesel Trucks (LHDV1) Light Heavy Duty Diesel Trucks (LHDV2) Medium Heavy Duty Diesel Trucks Heavy Heavy Duty Diesel Trucks Motorcycles Heavy Duty Diesel Urban Buses Heavy Duty Gas Urban Buses School Buses Other Buses Motor Homes TOTAL - On-Road Motor Vehicles Other Mobile Sources Aircraft Trains Ships & Commercial Boats Recreational Boats Off-Road Recreational Vehicles Off-Road Equipment Farm Equipment Fuel Storage - Other Mobile TOTAL - Other Mobile TOTAL MOBILE SOURCES VOC TOTAL ALL SOURCES

55 TABLE 4-2 EMISSION INVENTORY & FORECASTS FOR OXIDES OF NITROGEN FOR THE NORTH CENTRAL COAST AIR BASIN Ozone Seasonal Planning Inventory (Tons/Day) NOx SOURCE CATEGORY STATIONARY SOURCES: Fuel Combustion Electric Utilities Cogeneration Oil and Gas Production Manufacturing and Industrial Food and Ag Processing Service and Commercial Other TOTAL - Fuel Combustion Waste Disposal Landfills and Incinerators TOTAL Petroleum Production Oil and Gas Production TOTAL - Petroleum Production Industrial Processes Mineral Processes Other TOTAL - Industrial Processes Use of Banked Emissions TOTAL TOTAL STATIONARY AREA-WIDE SOURCES: Miscellaneous Processes Residential Fuel Combustion Prescribed Burns TOTAL - Miscellaneous TOT AREA-WIDE SOURCES

56 NOx SOURCE CATEGORY MOBILE SOURCES: On-Rd Motor Vehicles EMF07 Light Duty Passenger Light Duty Trucks (LDT1) Light Duty Trucks (LDT2) Medium Duty Trucks Light Heavy Duty Gas Trucks Light Heavy Duty Gas Trucks Med. Heavy Duty Gas Trucks Heavy Heavy Duty Gas Trucks Light Heavy Duty Diesel Trks Light Heavy Duty Diesel Trks Med. Heavy Duty Diesel Trks Heavy Heavy Duty Diesel Trks Motorcycles Heavy Duty Diesel Urban Buses Heavy Duty Gas Urban Buses School Buses Other Buses Motor Homes TOT - On-Road Motor Vehicles Other Mobile Sources Aircraft Trains Ships & Commercial Boats Recreational Boats Off-Road Recreational Vehicles Off-Road Equipment Farm Equipment TOTAL - Other Mobile TOTAL MOBILE SOURCES NOx TOTAL ALL SOURCES

57 TABLE 4-3 ADOPTED DISTRICT RULES LIMITING EMISSIONS OF OZONE PRECURSOR GASES RULE Initial Adoption TITLE VOC NO X 404 9/74 Sulfur Compounds and Nitrogen Oxides X 416 9/74 Organic Solvents X 417 9/74 Storage of Organic Liquids X 418 9/74 Transfer of Gasoline into Stationary Storage Containers X 419 9/74 Bulk Gasoline Plants and Terminals X /84 Effluent Oil Water Separators X 423 2/84 New Source Performance Standards X X 425 1/79 Use of Cutback Asphalt X 426 5/79 Architectural Coatings X 427 1/80 Steam Drive Crude Oil Production Wells X 429 9/87 Application of Nonarchitectural Coatings X 431 9/93 Emissions from Electric Utility Boilers X X 433 6/94 Organic Solvent Cleaning X 434 6/94 Coating of Metal Parts and Products X 436 5/95 Title V: General Prohibitory Rule X X /96 Municipal Solid Waste Landfills X 438 4/03 Open Outdoor Fires X X /89 Transfer of Gasoline into Vehicle Fuel Tanks X 4-14

58 Figure 4-1 NCCAB VOC EMISSION INVENTORY TREND 140 NCCAB VOC Emission Inventory 1990 to Tons per Summer Day Figure 4-2 NCCAB NOx EMISSION INVENTORY TREND NCCAB NOx Emission Inventory Tons per Summer Day

59 Figure Volatile Organic Compounds (VOC) 2007 NCCAB VOC Inventory 70 Tons/Day Other Fuel Combustion 1% Landfills 2% Petro Prod. & Marketing 3% Cleaning & Sfc Coatings 5% Industrial Processes 1% Electric Utilities 1% On-Road Motor Vehicles 26% Other Miscellaneous 6% Prescribed Fires 17% Solvent Evaporation 20% Other Mobile 18% Figure Volatile Organic Compounds (VOC) 2020 NCCAB VOC Inventory 60 Tons/Day Landfills 3% Petro Prod. & Marketing 4% Other Stationary Fuel Combustion 1% Industrial Processes 2% Electric Utilities 1% On-Road Motor Vehicles 14% Cleaning & Sfc Coatings 7% Miscellaneous Area 7% Solvent Evaporation 25% Prescribed Fires 22% Other Mobile 14% 4-16

60 Figure Oxides of Nitrogen (NOx) 2007 NCCAB NOx Inventory 81 Tons/Day Oth. Indust. Fuel Combustion 3% Electric Utilities 3% Industrial Processes 4% Miscellaneous 5% Manufact. & Industrial 16% On-Road Motor Vehicles 50% Other Mobile 19% Figure Oxides of Nitrogen (NOx) 2020 NCCAB NOx Inventory 53 Tons/Day Other Industrial Fuel Combustion 5% Industrial Processes 7% Electric Utilities 4% On-Road Motor Vehicles 29% Misc Area 8% Manufacturing and Industrial 30% Other Mobile 17% 4-17

61 Figure 4-7 EMISSIONS FROM ON-ROAD MOTOR VEHICLES Volatile Organic Compounds Oxides of Nitrogen Tons per Day Tons per Day EMFAC2007 VOC Trend EMFAC2007 NOx Trend Figure 4-8 COMPARISON OF MOTOR VEHICLE EMISSIONS WITH VMT - EMFAC Tons Per Day VMT - Millions of Miles per Day VOC + NOx From On-Road MV VMT - Millions of Miles Per Day 4-18

62 Figure 4-9 EMISSIONS FROM OFFROAD MOBILE SOURCES Volatile Organic Compounds Oxides of Nitrogen Tons per Day 10 5 Tons per Day OFFROAD2007 VOC Trend OFFROAD2007 NOx Trend Figure 4-10 EFFECT HIGH GROWTH MANUFACTURING & INDUSTRIAL CATEGORY ON STATIONARY SOURCE NOx EMISSIONS Oxides of Nitrogen Tons per Day All Stationary Sources Manufacturing & Industrial 4-19

63 Figure 4-11 EMISSIONS VS. POPULATION GROWTH 400 1,000,000 NCCAB Emissions (Tons/Day) , , ,000 NCCAB Population VOC + NOx - All Sources Population Figure 4-12 EFFECT OF DISTRICT RULES 431 AND 425 Effect of District Rule Electric Utilities Effect of District Rule Cutback Asphalt 18 7 Tons per Day Tons per Day NOx From Electric Utilities NOx Trendline VOCs From Cutback Asphalt VOC Trendline 4-20

64 5.0 ACHIEVING AND MAINTAINING THE STATE OZONE STANDARD 5.1 INTRODUCTION The basic strategy for improving air quality is to reduce emissions of those air pollutants which cause violations of ambient air quality standards. Because ozone is a regional pollutant, emissions affecting the entire North Central Coast Air Basin (NCCAB) are involved. Based on strategies for meeting the 1-hour standard, there are several approaches for determining the level of emission reductions needed to meet ozone standards. The first is to use a specific percentage of emission reductions over a given time frame until the standard is met. This approach is established in the California Clean Air Act (CCAA), which requires a 5% annual reduction until the standard is met. It requires adoption of all feasible measures if the 5% annual reduction cannot be achieved. A second approach involves achieving the emission reductions associated with the area s specific ozone design value, which is based on an actual monitored violation where local emissions played a significant role in the event. Another approach uses photochemical modeling. This allows for evaluation of a number of regional emission reduction scenarios. The results of these tests can provide districts with insights into the unique conditions, such as inter-basin transport, which impact air quality in their areas. Although photochemical modeling is optional because of the time and resources needed to develop this resource, the District has also pursued this approach and the results are summarized in this chapter MAINTAINING THE 1-HOUR STANDARD The NCCAB met the 1-hour standard in 2006 following many years of implementing emission reduction strategies. In order to maintain the standard, it will be necessary to continue these efforts so that the narrow margin of attainment increases and so that progress can be made toward meeting the more stringent 8-hour component of the standard MEETING AND MAINTAINING THE 8-HOUR STANDARD Although the regulatory guidance for achieving the State ozone standard has not been updated to reflect new considerations brought about by the introduction of the 8-hour standard, the same fundamentals remain in place regarding the relationship between reducing precursor emissions and improving ozone air quality. This involves building on the improvements brought about for the 1-hour standard. Since meeting the 8-hour standard involves a continuation of the strategy to reduce NO x and VOC, progress has already been made toward meeting the 8-hour standard as a result of efforts to achieve the 1-hour standard. However, given that the 8-hour standard is more stringent (i.e. produces more exceedances) than the 1-hour, additional effort will be needed. This must 5-1

65 occur in a regulatory environment where emission reductions are becoming increasingly scarce and less cost effective because most readily available measures have already been implemented in the effort to achieve the 1-hour standard. Much has been learned through the effort to achieve the 1-hour standard. While the same principles and strategies will continue to apply for the 8-hour standard, they will require further development to meet the 8-hour standard Although the following sections are based on efforts to achieve the 1-hour standard, they are modified whenever possible for application to the new 8-hour standard. The sections describe emission reduction strategies applicable to the NCCAB, the influence of transport on achieving the standard, as well as insights gained from the District s photochemical modeling project. The final section considers a range of dates when the 8-hour standard might be met. 5.2 EMISSION REDUCTION REQUIREMENTS FOR NONATTAINMENT AREAS Section of the California Clean Air Act states: (a) Each district plan shall be designed to achieve a reduction in district-wide emissions of 5 percent or more per year for each nonattainment pollutant or its precursors, averaged every consecutive three-year period, unless an alternative measure of progress is approved pursuant to Section (b) A district may use an alternative emission reduction strategy which achieves less than an average of 5 percent per year reduction in district-wide emissions if the district demonstrates to the state board, and the state board concurs in, either of the following: (1) That the alternative emission reduction strategy is equal to or more effective than the district-wide emission reductions in improving air quality. (2) That despite the inclusion of every feasible measure in the plan, and an expeditious adoption schedule, the district is unable to achieve at least a 5 percent annual reduction in district-wide emissions. (c) For purposes of this section and Section , reductions in emissions shall be calculated with respect to the actual level of emissions which exist in each district during 1990, as determined by the state board. All reductions in emissions occurring after December 31, 1990, including, but not limited to, reductions in emissions resulting from measures adopted prior to December 31, 1990, shall be included in this calculation. (Amended by Stats. 1996, Ch Sec.5.) 5.3 OZONE DESIGN VALUE STRATEGY The ARB provided guidance to the District in 1994 regarding the level of emission reductions needed to achieve the State ozone standard based on an ozone design value. An ozone design value is defined as the highest recorded violation during the three year period evaluated, excluding the days on which an exceptional event, extreme concentration event, or overwhelming transport from an upwind area occurred. Based on the "Second Triennial Review 5-2

66 of the Assessment of the Impacts of Transported Pollutants on Ozone Concentrations in California" prepared by the ARB, the District's design value was set at 0.10 ppm. The ARB's 1994 guidance estimated that a 20 percent reduction in 1987 (base year) VOC and NO x emissions was needed to meet the ozone standard based on a design value of 0.10 ppm. This reduction was addressed in the 1997 AQMP which showed that a 20 percent reduction from the 1987 emission inventory was 19.6 and 20.3 tons per day of VOC and NO x, respectively. The actual reductions achieved were 36 percent and 26 percent for VOCs and NO x, respectively. Although the emission reduction targets were met, air monitoring data for the NCCAB continued to indicate that the area had not achieved the standard. 5.4 ALL FEASIBLE MEASURES In 2000, with the focus no longer on the ozone design value strategy, the ARB stated that since the NCCAB did not attain the State ozone standard by 1997, that the "feasible measure" criterion is applicable to the District. In a letter dated December 8, 2000, the ARB Executive Officer stated that for districts that have not achieved a five percent annual reduction of nonattainment pollutants or their precursors, they are to implement every feasible measure on an expeditious schedule. The letter further recommended adoption of the ARB s Suggested Control Measure (SCM) for Architectural Coatings. In 2002, the District adopted the SCM for architectural coatings. In the 2004 plan, additional control measures were proposed to address the all feasible measures criterion. These were not implemented as the area came into compliance of the 1-hour standard without them. However, the need to consider these measures re-emerges in order to make progress toward meeting the 8-hour standard. 5.5 ARB TRANSPORT ASSESSMENTS Transport from urban areas upwind of the NCCAB can have a significant effect on our strategy to achieve the standard. As required by Section of the CCAA, the ARB is to periodically assess the impact of emissions from upwind air basins on violations in the downwind areas VINTAGE OF EXISTING ASSESSMENTS It should be noted that the transport assessments described in this section have not been reaffirmed by ARB since The existing assessments are based on peak 1-hour exceedance events occurring in the 1990 s, and have not been updated to reflect more recent violations of the 1-hour standard, or violations of the State 8-hour standard. While the general findings from the 1-hour assessments should remain relevant, 8-hour transport events are likely more complex because, rather than focusing on a discrete 1-hour peak, 8-hour exceedances are spread over many hours. The longer duration of 8-hour events suggests that a wider range of factors can contribute to the exceedance. The low threshold of the State 8- hour standard also suggests that impact can be triggered at a lower level than the for the 1-hour standard. Regional carryover from various areas as well as naturally occurring background may also play a larger role. 5-3

67 5.5.2 SUMMARY OF EXISTING ASSESSMENTS The historical assessments are based upon a preponderance of the available evidence. The analyses therefore consider a variety of meteorological and air quality factors, including but not limited to winds and ozone levels at the surface and aloft, inversion characteristics, large scale synoptic weather patterns, temporal and spatial patterns for both ozone and temperature, terrain influences as well as the spatial distribution and relative size of each area s precursor emission inventory. In this regulatory process, the ARB formally determines which areas are legally declared as upwind air basins which cause or contribute to violations in downwind air basins. The resulting upwind/downwind relationships are referred to as transport couples. Upwind air basins have regulatory responsibilities to mitigate emissions sufficient for the downwind areas to achieve the standard. The regulatory transport couples are codified in Section of Title 17, California Code of Regulations. The most significant transport couple affecting the NCCAB is the upwind relationship of the San Francisco Bay Area Air Basin (SFBAAB), which is due to in part to a continuous terrain feature (Santa Clara Valley/San Benito River Valley) which links the two areas. This is referred to as the SFBAAB to NCCAB transport couple. This couple was initially identified in the first transport assessments in 1990 and has been reaffirmed in subsequent assessments, including the ARB s most recent transport review in Transport contributions are described as overwhelming, significant, inconsequential or inconclusive. Transport is deemed as inconsequential if upwind emissions are not transported at all or did not appear to contribute significantly to the violation of the standard in the downwind area. A transport contribution is deemed significant if the upwind emissions contributed measurably to violations of the ozone standard in the downwind area on any single day. A transport contribution is overwhelming if emissions from the upwind area independently caused a violation of the State ozone standard in the downwind area on any single day. Transport is considered inconclusive when there are insufficient data to determine the degree of transported air pollution. Table 5-1 summarizes the current ARB transport couples from their 2001 report 2) which identifies the regulatory upwind areas and the assessed degree of impact on the peak 1-hour ozone level. Day specific impact findings can vary from event to event depending largely on the meteorological conditions causing the particular transport episode. The degree of impact from upwind areas on 1-hour exceedance events should diminish as regional emission inventories of ozone precursors diminish. The contribution categories indicate that transport from the SFBAAB has a particularly strong influence on our attainment status. The transport assessments for 1994 and 1995 summarized in Table 5-2 indicate that 50 percent of NCCAB exceedances are the result of overwhelming transport from the SFBAAB, meaning that the exceedance would have occurred even with little or no emission contribution from the NCCAB. Thirty percent of the exceedances are classified as significant meaning that emissions from both the upwind and local areas contributed measurably to exceedances of the standard. Upwind areas identified as significant include the SFBAAB and the SJVAB. The remaining exceedances in Table 5-2 are classified as extreme concentration events or inconclusive. 5-4

68 5.5.3 APPLICATION TO CURRENT CONDITIONS In order to consider applicability of the findings in Table 5-2 to 8-hour exceedance events, the table shows the daily peak 8-hour concentration as well as the 1-hour exceedance. In each case, except the 7/14/95 event in Scotts Valley, an 8-hour exceedance was recorded on the day of the peak 1-hour event and the peak 1-hour reading contributed to the 8-hour exceedance. Consequently, the transport findings applicable to the 1-hour peak should at least partially apply to the 8-hour exceedance. Also, the general upwind/downwind relationships shown in Table 5-1 are likely still applicable because they are based on wind flow regimes that recur during ozone episodes. However, the degree of transport impact may be gradually diminishing as regional emission inventories diminish, at least in terms of the 1-hour standard. This coincides with the general downward trend in the area s design value. As applied to the 8-hour standard, the degree of impact from regional and local sources is likely raised again because of the low threshold of the new standard. Since the ARB transport assessments indicate that emissions from the SFBAAB, the SJVAB as well as the NCCAB contribute to violations, continuing emission reductions in the entire region will likely be necessary to maintain the 1-hour standard and to eventually achieve the State 8-hour standard. 5.6 FINDINGS FROM PHOTOCHEMICAL MODELING PROJECT Because the issues of transport and assessing progress toward achieving the standard are important, the District contracted with researchers at the BAAQMD to use their regional photochemical model to address these two complex issues. Although this study was geared to the 1-hour standard, the findings should have general applicability to the 8-hour standard as well. The findings from this multi-year project 2) are summarized in the following sections TRANSPORT MODELING A primary objective of the project was to assess the influence of transported versus local emissions on the air quality of the NCCAB. This was undertaken using a modeling technique called emission masking. In an emission masking scenario, the base case episode is rerun in the model with emissions of ozone forming pollutants from specific air basins being significantly reduced. The corresponding change in ozone throughout the NCCAB for each reduction scenario is then determined by the model. Using a regional base case episode that occurred in August 1990, the BAAQMD measured the ozone response of the Urban Airshed Model (UAM-V) to reductions in emission inventories from the San Francisco Bay Area Air Basin (SFBAAB), the San Joaquin Valley Air Basin (SJVAB) and the NCCAB to assess the influence of transport on the NCCAB. Three anthropogenic (pollution originating from human activities) emission masking scenarios were run for each air basin. These included: (1) 50% reduction of the VOC inventory only, (2) 50% reduction of the NO x inventory only, and (3) 50% reduction of both the VOC and NO x inventories. Three emission masking scenarios were developed for each air basin and a total of nine scenarios were run. 5-5

69 The following summarizes the major findings of the emission masking scenarios that were run for each of the three air basins in terms of impacts on the NCCAB. In this discussion, the terms "NO x sensitive and VOC sensitive areas are used. NO x sensitive areas of the NCCAB are areas where ozone formation was limited by the availability of NO x and VOC sensitive areas are areas of the NCCAB where ozone formation was limited by the availability of VOCs. NO x sensitive areas tend to benefit the most from NO x emission reductions, while VOC sensitive areas benefit most from VOC reductions. SFBAAB Impacts on NCCAB: Areas of the NCCAB where ozone tended to be highest were impacted by both NO x and VOC emissions transported from the SFBAAB. For some areas, the contribution was sufficient to cause ozone to exceed the standard. Ozone at the Pinnacles National Monument was significantly impacted by SFBAAB NO x emissions. SFBAAB VOC reductions were effective at reducing ozone in the northern portion of the NCCAB by about 5-10 ppb on 5 August when ozone was highest. This reduction was sufficient to eliminate the August 5 th 100 ppb exceedances that occurred at Hollister. Hollister had different sensitivity responses on August 5 th versus August 6 th. This suggests Hollister may be in a transition zone between SFBAAB VOC sensitivity and SFBAAB NO x sensitivity. On August 5 th, highest ozone occurred in northern San Benito County. At the locations where ozone was highest, SFBAAB NO x reductions were less effective than SFBAAB VOC reductions. This may be because the air transported from the SFBAAB has an urban VOC sensitive precursor mix. However, other locations, downwind of the VOC sensitive regions, such as the area south of Hollister and extending south to the Pinnacles, did benefit from SFBAAB NO x reductions. SFBAAB NO x reductions produce a significant reduction (up to 10 ppb) in ozone in areas of elevated terrain in Santa Cruz County. SFBAAB NO x reductions also produce a lesser but more wide-spread ozone reduction over a larger portion of the NCCAB. The combined SFBAAB VOC and NO x reductions significantly reduced ozone in most of San Benito County. Local NCCAB Impacts: Air laden with NCCAB precursors appeared to be primarily NO x sensitive, meaning that ozone formation due to local emissions was more limited by the availability of NO x as opposed to the availability of VOCs. NCCAB NO x contributed significantly to local ozone levels. NCCAB NO x emission reductions reduced ozone values throughout Monterey County and in areas where ozone was simulated to be high, suggesting that there may be episodes where NCCAB NO x controls would be effective at reducing ozone. 5-6

70 Pinnacles, King City and San Ardo were all sensitive to NCCAB NO x. Since these locations are in the downwind corridor of the Moss Landing Power Plant, this supports the large NO x reductions required by District Rule 431. The transport impacted the Pinnacles site was sensitive to NO x reductions from both the SFBAAB and the NCCAB. However, the 50% SFBAAB NO x reduction scenario reduced simulated ozone more than the corresponding scenario for the NCCAB, suggesting that NO x from the SFBAAB may have a greater impact on ozone levels at Pinnacles than NO x from the NCCAB. SJVAB Impacts on NCCAB: SJVAB NO x reductions produced some reductions in simulated ozone in the eastern portion of the NCCAB. This suggests that there may be conditions under which SJVAB NO x reductions have some benefit in the NCCAB. SJVAB VOC reductions had no measurable effect on the NCCAB in this modeling exercise EPISODIC PATTERNS The BAAQMD statistically evaluated the spatial pattern of ozone in Northern California during periods when high ozone levels were recorded in the NCCAB. The cluster analysis, which was based on the years , revealed three distinct patterns when ozone was high in the NCCAB. These were Cluster A (70% of NCCAB exceedances), Cluster B (21% of NCCAB exceedances) and Cluster C (only 9%). The most common exceedance pattern (Cluster A) is when the Pinnacles records a singularly high ozone reading in comparison to other stations in both the NCCAB and SFBAAB. The majority of all NCCAB exceedance days fell into Cluster A and 95% of those exceedances occurred at the Pinnacles National Monument. A probable cause of the anomalously high readings at Pinnacles is delayed transport aloft to this high elevation site. Often previous day ozone is vented from the SFBAAB resulting in lower values in the upwind source region and higher values downwind. The regional pattern where Pinnacles records a singularly high reading continues with exceedances of the State 8-hour standard. On most days when Pinnacles records an 8-hour violation, all other stations in the NCCAB are within the 8-hour standard. This has significant implications on the NCCAB s attainment status because the pattern at Pinnacles is much different than what occurs elsewhere in the air basin YEAR 2010 PROJECTION The projected change in NCCAB ozone from 1990 to 2010 was investigated by simulating the August 3 to 6, 1990 episode using an estimated year 2010 emission inventory. In 2010, the domain-total anthropogenic VOC inventory was 54% of the 1990 VOC inventory and 50% of the NO x inventory. Thus, the overall inventory of ozone precursors in Central California in 2010 is estimated to be roughly half of what it was in

71 The results of this simulation are shown in Figure 5-3, which indicates: That while the severity and extent of ozone exceedances are reduced compared 1990, some areas of the NCCAB may still not achieve the standard with current control measures in place. Additional controls in both the NCCAB and SFBAAB may be needed to avoid future exceedances, especially under adverse meteorological conditions. This is especially important for the NCCAB, which tends to be very close to the attainment threshold, and year to year variations in weather can be an important factor in determining whether or not air quality meets the standard. Although the NCCAB met the 1-hour standard in 2006 by a narrow margin, it is not unreasonable for the model to indicate that exceedances could still occur in This can occur due to year to natural year to year variation, which can cause the NCCAB to fluctuate above and below the standard. It should also be noted that since the area s attainment status depends on exceedances accumulated over a 3-year period, infrequent exceedances of the 1- hour standard could still occur in the future that would not necessarily cause the area to no longer meet the 1-hour component of the standard. The modeled 1990 SFBAAB to NCCAB transport corridor can clearly be seen in Figure 5-1. This is the region of high ozone extending from the central SFBA through San Benito County, including Pinnacles National Monument, and then into southern Monterey County. Although reduced in 2010, the transport corridor is still evident in the 2010 simulation, especially in the areas of highest ozone. Thus, while the severity of transport should be reduced in the future due to regional controls on emission sources, it will likely continue to influence air quality in the NCCAB at least through the year The areas within the NCCAB exceeding the state ozone standard is reduced. The areas of the NCCAB remaining in excess of the standard, primarily northeastern San Benito County, are areas that the transport assessments indicated are impacted by emissions from the SFBAAB, the SJVAB as well as local NCCAB emissions. Based on the modeled 2010 nonattainment prediction, additional controls on ozone precursors in both the NCCAB and the SFBAAB, may be needed for the NCCAB to achieve the state standard. The "Bay Area-North Central Coast Photochemical Modeling Investigation of Ozone Formation and Transport, Final Report", December 2000 is available upon request. 5.7 MEETING AND MAINTAINING THE STATE OZONE STANDARD Effective July 26, 2007, the ARB designated the NCCAB as a nonattainment area for the State ozone standard. Although the area has met the 1-hour criteria of the standard, it fails to meet the new 8-hour criteria. The area s 1-hour design value only meets the 1-hour requirement by a 1% margin and will likely fluctuate above and below the standard for the next several years due to year to year variation in the weather. The area s 8-hour design value is nearly 20% over the standard and will take years to meet. 5-8

72 5.7.1 REGIONAL SCOPE Table 2-4 in Chapter 2 indicates that three stations including Pinnacles National Monument, Hollister and Scotts Valley do not meet the State standard because they do not comply with the 8-hour requirement of the standard. Past ARB transport assessments indicate that these sites can be impacted by significant to overwhelming transport. In order to achieve the standard at these sites, emission reductions in the NCCAB alone may not be sufficient for the area to achieve the standard. Emission reductions in the NCCAB will need to be coupled with regional emission reductions in the upwind air basins as well. Control strategies in the upwind areas are outlined in the plans for each region. The current plan for the SFBAAB is the 2005 Bay Area Ozone Strategy 3), which was developed by the Bay Area Air Quality Management District (BAAQMD). This plan adopted measures addressing the Transport Mitigation Requirements of the CCAA. The District will review periodic updates to the BAAQMD s ozone plan, particularly with regard to progress in the area of transport mitigation ARB TRANSPORT MITIGATION REQUIREMENTS ARB s transport mitigation requirements became effective on January 3, 2004 and are outlined in Section of Title 17 of the California Code of Regulations. The measures applicable to upwind areas are summarized below: 1. Adopt and implement all feasible measures as expeditiously as practicable. 2. Adopt and implement best available retrofit control technology on existing stationary sources of ozone precursor emissions as expeditiously as practicable. 3. Adopt a no net increase permitting program for new or modified stationary sources that emit 10 tons or greater per year of an ozone precursor. 4. Include measures sufficient for downwind areas impacted by overwhelming transport to attain the state ambient air quality standard for ozone by the earliest practicable date. The measures are in place due to transport impacts on several downwind areas, including the NCCAB. Measure 4 is triggered by upwind/downwind transport couples characterized by overwhelming transport, such as the SFBAAB/NCCAB couple. Measures 1 through 4 apply to the SFBAAB. Measures 1, 2, and 4 apply to the SJVAB. Measure 4 for the SJVAB is in effect due to overwhelming transport to downwind areas other than the NCCAB, although the NCCAB should also benefit from this provision POTENTIAL BENEFITS OF THE 2006 GLOBAL WARMING SOLUTIONS ACT New state-wide incentives emerging from California s Global Warming Solutions Act of 2006 (AB 32) may contribute toward progress in meeting the 8-hour standard. Many of the incentives focus on reducing energy use, fuel combustion and travel. These types of measures also have cross pollutant benefits in terms of reducing emissions of ozone precursors. Potential cross pollutant benefits of AB 32 will be considered in subsequent updates of the AQMP. 5-9

73 5.8 PROJECTING AN ATTAINMENT DATE The CCAA does not specify a date by which attainment should occur, only that the standard should be achieved as expediently as possible by implementing all feasible measures. It is not possible to accurately determine a specific attainment year due to the uncertainties in the inventory forecasts and year to year variations in the weather. However, it is feasible to estimate a general range of years using various criteria and trends based on currently adopted controls. Both components of the standard must be met to achieve the standard. The different components of the standard will also have different eventual attainment dates. Given that the 8- hour component is the more difficult to achieve, its attainment date will be much further into the future than the 1-hour HOUR STANDARD As discussed in Chapter 2, the NCCAB achieved the 1-hour standard based on 2004 to 2006 data, which is a significant milestone. However, given that the 1-hour EPDC, a key statistic used by ARB to determine an area s attainment status, was barely within the standard, it is likely that the area could fluctuate above and below the standard until regional emission reductions are sufficient to override year to year variations in the weather. Given the favorable situation regarding the 1-hour standard, focus shifts to achieving the more challenging 8-hour component of the standard HOUR STANDARD AIR QUALITY TREND APPROACH One approach for estimating a range of attainment dates for the 8-hour standard is to develop a simple liner extrapolation of the trend in the monitored EPDCs. Although this may underestimate the date because progress and emission reductions tend to diminish as the standard is approach, it at least serves as a demonstration of how far distant in the future attainment be occur. This scenario is illustrated in Figure 5-2. The projection suggests a date out near the year Although the actual date may be further in the future, this suggests that the 8-hour component of the standard will not be met for many years HOUR STANDARD EMISSION INVENTORY TREND APPROACH Another approach is to evaluate regional emission inventory trends and how those could reduce the area s current design value, which is based on data from Pinnacles NM, a site impacted by emissions transported from several air basins. This requires consideration of regional emissions from the NCCAB, the San Francisco Bay Area, the influence of natural background and how far above the standard the current design value is. The NCCAB s 8-hour design value (EPDC) is ppm, based on 2003 to 2005 data. Assuming background to be about 0.03 ppm, this leaves a margin of ppm between background and the design value which is due to anthropogenic emissions. Since the design value is ppm above the standard, the anthropogenic increment needs to be reduced from ppm to ppm, or about 25%. A rule of thumb for the relationship between the response of ambient ozone levels to regional emission reductions is that for every 2% reduction in emissions, ozone is reduced by about 1%. Since the anthropogenic air quality increment needs to be reduced about 25%, this suggests that a 50% reduction in regional emissions is needed for the NCCAB to achieve the 8-hour ozone standard. 5-10

74 Figure 5-3 shows the combined inventory trend for NOx emissions from the SFBA and NCCAB between 2005 and 2030, based on currently adopted controls. The combined NO x inventories for the SFBA and NCC are shown for two reasons: 1) The ARB transport assessments indicate that stations in the NCCAB having the highest ozone can be impacted by both overwhelming transport from the SFBA and significant impacts from local emissions, and 2) Photochemical modeling indicates that areas in the NCCAB having the highest ozone are most sensitive to NO x emissions. The large NO x inventory from the SJVAB could The figure indicates that after 2020 NO x emissions are forecast to level out at just over 50% of the level that existed in Since a full 50% reduction would be preferable to attain the standard, this suggests that the NCCAB may hover very close to the attainmentnonattainment threshold after the year 2020 unless additional emission reductions can be found. Additional NO x reductions may be beneficial in the future to assure compliance with the 8-hour standard. Figure 5-3 also illustrates the relative size and importance of the SFBA s large emission inventory. Regional NO x reductions would be slightly higher if the large NO x inventory from the SJVAB were included in the analysis. However, since the degree of impact is less than that of the SFBA, it was not included. Regional emission reduction strategies only apply to the increment above background, so the lower background; the more effect regional controls have on overall ambient ozone levels. Should background be higher than 0.03 ppm, attainment could occur at a later date, if background is lower, attainment could occur earlier SYNOPSIS The NCCAB achieved the 1-hour component of the standard in 2006, although remaining in compliance could fluctuate based on year to variations in weather. It is uncertain when the 8- hour standard will be met although it won t likely be for many years. The projection scenarios suggest that it won t be until sometime after 2025 and that additional emission reductions may be necessary to assure progress. This is approximately what the situation was with the 1-hour standard in the late 1980 s. Attainment could be reached at an earlier date if a station representative of a populated area were used as the area s design site in place of the remote Pinnacles station. 5-11

75 Figure 5-1 Comparison of photochemical modeling results for 1990 and Image on the left represents maximum ground-level hourly ozone concentrations (ppb) for an actual regional episode that occurred on August 5-6, Results on the right are maximum concentrations for the same episodic conditions, only with emission projections for the future year The + on the figures represent sites where ambient ozone monitoring was conducted in