A COMPARISON STUDY OF THE OVERALL FIT FACTORS BETWEEN THE PORTACOUNT AND THE FIT TESTER Jeff Funke. A thesis submitted to the

Transcription

1 A COMPARISON STUDY OF THE OVERALL FIT FACTORS BETWEEN THE PORTACOUNT AND THE FIT TESTER 3000 by Jeff Funke A thesis submitted to the Safety, Health and Industrial Hygiene Department Montana Tech of The University of Montana for the degree of Master of Science in Industrial Hygiene Montana Tech of The University of Montana Butte, Montana December 2000

2 ii ABSTRACT The primary objective of this study was to determine if there is a significant difference between the overall fit factors given by the particle-based system of the Portacount Plus and the pressure-based system of the Fit Tester Additionally, this study explored the effects of gender and protocol on overall fit factors given by both the Portacount and Fit Tester This study covers the following topics: protection factors categories of respirators, elements of a respiratory protection program, respirator selection, both qualitative and quantitative fit testing, and the internal operating mechanisms of the Portacount and the Fit Tester This comparison study consisted of a total of twenty subjects ten males and ten females between the ages of 18 and 55. Each of the subjects was fit tested four times, in random order, for a total of 80 tests. The protocols used in this study were the OSHA protocol and the Modified protocol. The Modified fit test protocol was developed by Crutchfield et al. from the University of Arizona. The Modified protocol was developed to be a shorter less time consuming alternative to the OSHA protocol. All subjects in this study were fitted with a North model 7700 half-mask negative pressure air-purifying respirator. The raw data collected from the fit tests was analyzed with the Minitab statistical package. The results of this analysis revealed that there is a significant difference between the overall fit factors given by the Portacount and the Fit Tester No significant difference was found in overall fit factors due to gender. The Modified protocol was found to be as stringent as the OSHA protocol for both the Fit Tester 3000 and the Portacount Plus.

3 iii ACKNOWLEDGEMENT I would like to thank the faculty and staff of the Safety, Health and Industrial Hygiene Department at Montana Tech for their patience and support. I would also like to thank all of the test subjects who willing participated in this study. A special thank you to Adam Harbour for donating the North halfmask respirators and HEPA filters used in this study. A sincere thank you to Doug and Ann Drew for their support during my education at Montana Tech. Finally, a sincere thank you to my wife Julie, and son Conner who have brought so much to my life.

4 iv TABLE OF CONTENTS page ABSTRACT ii ACKNOWLEDGMENTS..iii TABLE OF CONTENTS iv LIST OF TABLES.vii LIST OF FIGURES..viii 1.0 INTRODUCTION Statement of the Problem Research Hypotheses BACKGROUND Protection Factors Categories of Respirators Elements in an Effective Respiratory Protection Program Respirator Selection Fit Testing Qualitative Fit Testing Quantitative Fit Testing Generated Test Aerosol QNFT Ambient Aerosol QNFT Controlled Negative Pressure CNP QNFT Fit Checking Literature Research MATERIALS Portacount Plus 8020 Quantitative Fit Test Instrument Fit Tester 3000 Quantitative Fit Test Instrument Quantitative Fit Test Adapters for the Portacount Plus Quantitative Fit Test Adapters for the Fit Tester METHODS Prescreening of Test Subjects Portacount Plus Daily Calibration. 39

5 v 4.3 OSHA Protocol Portacount Fit Tester 3000 Daily Calibration OSHA Protocol Fit Tester Modified Protocol Portacount Modified Protocol Fit Tester Statistical Analysis Methods RESULTS AND DISCUSSION Machine Comparisons Protocol Comparisons Portacount Protocol Comparisons Fit Tester Gender Comparisons for the Portacount Using the Modified Protocol Gender Comparisons for the Portacount Using the OSHA Protocol Gender Comparisons for the Fit Tester 3000 Using the Modified Protocol Gender Comparisons for the Fit Tester 3000 Using the OSHA Protocol Additional Statistical Analysis Discussion CONCLUSION RECOMMENDATIONS FOR FURTHER RESEARCH REFERENCES..60 APPENDIX A APPENDIX B APPENDIX C APPENDIX D APPENDIX E APPENDIX F APPENDIX G Respirator Decision Logic.62 NIOSH Guide to the Selection and Use of Particulate Respirators Certified Under 42 CFR Fit Testing Procedures (General Requirements) North Adapter Installation. 71 Sample Data Sheets for the Fit Tester 3000 and the Portacount..74 Portacount Plus Daily Calibration.79 OSHA Protocol Portacount....82

6 vi APPENDIX H APPENDIX I APPENDIX J APPENDIX K APPENDIX L APPENDIX M APPENDIX N OSHA Protocol Fit Tester Modified Protocol Portacount 88 Modified Protocol Fit Tester Raw Data Normality Test...97 Plot ff vs. Machine Plot ff vs. Protocol

7 vii LIST OF TABLES page Table I Normal Exercise Duration For the Portacount Plus Table II Grimace Exercise Duration For the Portacount Plus Table III Normal Work Rate Categories For the Fit Tester Table IV Cartridge Resistance Categories For the Fit Tester Table V Summary Statistics of Fit Factors by Protocol and Instrumentation. 44 Table VI Summary Statistics of Fit Factors by Protocol, Instrumentation, and Gender...45 Table VII Results of Two-Way ANOVA lnff vs. Block, Machine, Protocol 54

8 viii LIST OF FIGURES page Figure 1 Typical High Efficiency Particulate Filter Figure 2 Typical half-mask respirator...18 Figure 3 Schematic of Portacount Plus...32 Figure 4 Results of ANOVA on the Fit Tester 3000 and the Portacount using the OSHA Protocol Figure 5 Results of ANOVA on the Fit Tester 3000 and the Portacount using the Modified Protocol Figure 6 Results of ANOVA on the Portacount comparing Modified and OSHA Protocol Figure 7 Results of the ANOVA on the Fit Tester 3000 comparing Modified and OSHA Protocol. 49 Figure 8 Figure 9 Figure 10 Figure 11 Results of ANOVA for the Portacount comparing Male and Female overall fit factors using the Modified Protocol...50 Results of ANOVA for the Portacount comparing Male and Female overall fit factors using the OSHA Protocol...51 Results of ANOVA for the Fit Tester 3000 comparing Male and Female overall fit factors using the Modified Protocol Results ANOVA for the Fit Tester 3000 comparing Male and Female overall fit factors using the OSHA Protocol... 53

9 9 1.0 INTRODUCTION The primary goal of all occupational safety and health programs is to prevent the adverse health effects associated with occupational exposures. The preferred Industrial Hygiene procedure for controlling occupational exposures is to implement engineering and/or administrative controls. Unfortunately, not all occupational exposures can be reduced to an acceptable level due to inadequacy in technology or economic feasibility. Personal protective equipment (i.e. respirators) is used in these situations to reduce exposures to a point below the occupational exposure limit. The OSHA Technical Manual Section VII (1999): Chapter 2 Respiratory Protection lists the following situations where the use of respiratory protection is appropriate: certain maintenance and repair operations, emergencies, or during periods when engineering controls are being installed. The use of respirators can also be justified to reduce worker exposure in cases where work practices and engineering controls alone cannot reduce exposure levels to an acceptable level. In these cases respirators are an essential element in protecting workers from occupational exposures. The OSHA Technical Manual Section VII: Chapter 2 Respiratory Protection also lists a number of variables that affect the level of protection given by respiratory protective devices. Respirators can only provide adequate protection if they are properly selected for the task; are fitted to the wearer and are consistently donned and worn properly; and are properly maintained so that they continue to provide the protection required for the work situation. OSHA has estimated that five million

10 10 workers are currently using respirators to protect themselves from occupational exposures. 1.1 Statement of the Problem If respirators are to be effective in protecting worker s from airborne contaminants they must fit properly. ANSI Z states that A qualitative or quantitative respirator fit test shall be used to determine the ability of each individual respirator wearer to obtain a satisfactory fit with a tight-fitting respirator. A fit test is a procedure that uses a protocol to qualitatively or quantitatively evaluate the fit of a respirator. A quantitative fit test describes the degree of the fit (the fit factor) of the respirator and is identified as the ratio of the challenging aerosol concentration outside the mask to the aerosol concentration inside the mask. A number of test instruments and protocols have been developed to evaluate respirator fit. Two of the instruments used to quantitatively determine respirator fit are the ambient aerosol condensation nuclei counter Portacount TM and the controlled negative pressure Fit Tester While both instruments obtain a fit factor, they measure fit in two entirely different ways. Fit test protocols are an elaborate set of exercises designed to simulate workplace activities. OSHA has adopted a set protocol, however there is little information that provides the rationale for the fit test exercises that have been adopted. The purpose of this study was to determine if there is a significant difference between the overall fit factors given by the two instruments, and to explore the effect of using different protocols.

11 Research Hypotheses The following are the hypotheses tested during this project: RH1 The overall fit factors obtained by the Fit Tester 3000 will be significantly different than the overall fit factors obtained by the Portacount using the OSHA protocol. NH1 The overall fit factors obtained by the Fit Tester 3000 will not be significantly different than the overall fit factors obtained by the Portacount using the OSHA protocol. RH2 The overall fit factors obtained by the Fit Tester 3000 will be significantly different than the overall fit factors obtained by the Portacount using the Modified protocol. NH2 The overall fit factors obtained by the Fit Tester 3000 will not be significantly different than the overall fit factors obtained by the Portacount using the Modified protocol. RH3 The overall fit factors obtained by the Portacount using the Modified protocol will be significantly different than the overall fit factors obtained by the Portacount using the OSHA protocol. NH3 The overall fit factors obtained by the Portacount using the Modified protocol will not be significantly different than the overall fit factors obtained by the Portacount using the OSHA protocol.

12 12 RH4 The overall fit factors obtained by the Fit Tester 3000 using the Modified protocol will be significantly different than the overall fit factors obtained by the Fit Tester 3000 using the OSHA protocol. NH4 The overall fit factors obtained by the Fit Tester 3000 using the Modified protocol will not be significantly different than the overall fit factors obtained by the Fit Tester 3000 using the OSHA protocol. RH5 The overall fit factors obtained by male subjects using the Portacount with the Modified protocol will be significantly different than the overall fit factors obtained by female subjects using the Portacount with the Modified protocol. NH5 The overall fit factors obtained by male subjects using the Portacount with the Modified protocol will not be significantly different than the overall fit factors obtained by female subjects using the Portacount with the Modified protocol. RH6 The overall fit factors obtained by male subjects using the Portacount with the OSHA protocol will be significantly different than the overall fit factors obtained by female subjects using the Portacount with the OSHA protocol. NH6 The overall fit factors obtained by male subjects using the Portacount with the OSHA protocol will not be significantly different than the overall fit factor obtained by female subjects using the Portacount with the OSHA protocol.

13 13 RH7 The overall fit factors obtained by male subjects using the Fit Tester 3000 with the Modified protocol will be significantly different than the overall fit factors obtained by female subjects using the Fit Tester 3000 with the Modified protocol. NH7 The overall fit factors obtained by male subjects using the Fit Tester 3000 with the Modified protocol will not be significantly different than the overall fit factors obtained by female subjects using the Fit Tester 3000 with the Modified protocol. RH8 The overall fit factors obtained by male subjects using the Fit Tester 3000 with the OSHA protocol will be significantly different than the overall fit factors obtained by female subjects using the Fit Tester 3000 with the OSHA protocol. NH8 The overall fit factors obtained by male subjects using the Fit Tester 3000 with the OSHA protocol will not be significantly different than the overall fit factors obtained by female subjects using the Fit Tester 3000 with the OSHA protocol.

14 BACKGROUND The concept of protecting workers from occupational exposure is over 2000 years old. The first recorded effort to reduce exposures to hazardous airborne contaminants was by Plinius Secundus (Pliny the Elder). Pliny recorded the use of loose fitting animal bladders in slave mines to protect workers from the inhalation of red oxide lead. Fortunately, respiratory protection has made dramatic improvements since early Roman times. Today we have a variety of respirators with filters that are highly efficient, inexpensive, and have low breathing resistance. Additionally respirators are currently being designed that are smaller, more comfortable to wear, and are more protective than their predecessors. 2.1 Protection Factors There are two factors used to quantify respirator performance; fit factor (FF), and the assigned protection factor (APF). The (FF) measures the degree of the fit of the respirator to the wearers face. There are a number of variables that effect the fit factor. These parameters are leak sites, breathing patterns, and the type of respirator used. The majority of leaks that occur are circular or rectangular in shape. Most of these leaks are due to wrinkles and awkward facial contours near the nose and chin. Another factor that effects the seal between the respirator and the wearer s skin is facial hair. Facial hair in the form of beards, mustaches, sideburns, and stubble compromise the seal creating a pathway for contaminated air to enter the facepiece. The definition of APF according to NIOSH is a measure of the minimum anticipated level of respiratory protection that would be provided, by a properly

15 15 functioning respirator, to a large percentage of properly fitted and trained wearers. The maximum use concentration for a respirator is generally determined by multiplying a contaminant s PEL (or TLV) by the protection factor assigned to the respirator. It is generally assumed that when a respirator is properly used and maintained that it will provide a level of protection equal to or greater than its assigned protection factor for the vast majority (i.e. 95%) of the population wearing respirators. Lenhart et al. (1984) stated, Assigned protection factors have, however, not been based on actual measurements of workplace protection factors. Instead, they have been based on laboratory test in which a group of respiratory wearers perform a specific regimen of head and body movements while in a test chamber containing a challenge aerosol. The development of respiratory field studies and the evolution of workplace protection factor have addressed the need for actual workplace performance tests for respirators. A workplace protection factor is a measure or evaluation of the actual protection provided by a properly selected, functioning, and donned respirator in workplace conditions. A workplace protection factor is a tool to evaluate the level of protection provided by a respirator in the workplace. 2.2 Categories of Respirators Respirators are classified into two general types, air purifying and atmospheresupplying respirators. Air purifying respirators are devices that remove contaminants from the ambient air. Atmosphere-supplying respirators are devices that convey uncontaminated air from another source.

16 16 Air purifying respirators can be sub-categorized into three general types based on their filter or air purifying element: particulate removing, vapor and gas removing, and a combination of the two. The OSHA Technical Manual Section VII: Chapter 2 Respiratory Protection states, Air purifying particulate-removing respirators are designed to reduce inhaled concentration of nuisance dust, fumes, toxic dust, radon daughters, asbestos-containing dusts or fibers, or any combination of these substances, by filtering most of the contaminants from the inhaled air before they enter the breathing zone of the worker. The filtration mechanisms consist of interception, sedimentation, inertial impaction, diffusion, and electrostatic capture. Air-purifying respirators equipped with high efficiency particulate air filters (HEPA) were evaluated in this study. A HEPA filter is a filter that is at least 99.97% efficient in removing monodispersed particles of 0.3 micrometers in diameter or larger. (See Figure 1.) Figure 1. Typical High Efficiency Particulate Filter (NIOSH, 1987).

17 17 Other air-purifying respirators are equipped with sorbent elements (canisters or cartridges) that remove vapors and gases through adsorption and absorption. Combination cartridges are used to protect workers from particulates, gases and vapors. Atmosphere-supplying respirators are classified by two variables: how the air is supplied and how the air supply is regulated. Air is supplied by two basic methods selfcontained breathing apparatus (air or oxygen is carried in a tank on the worker s back, similar to SCUBA gear); and supplied air (compressed air from a stationary source is supplied through a high-pressure hose connected to the respirator); or a combination of the two. There are two basic types of respirators air-purifying, and atmosphere-supplying. Both of theses come in tight-fitting (negative pressure), and loose-fitting (positive pressure) models. The OSHA Technical Manual Section VII: Chapter 2 Respiratory Protection states, tight-fitting or negative pressure respirator is designed to form a seal with the face of the wearer. It is available in three types: quarter mask, half mask, and full facepiece. The quarter mask covers the nose and mouth, where the lower sealing surface rests between the chin and the mouth. The half mask covers the nose and the mouth and fits under the chin. The full facepiece covers the entire face from below the chin to the hair line. Negative pressure air-purifying half mask respirators were evaluated in this study. These respirators are composed of an inhalation valve, exhalation valve, facepiece, air-purifying element, and head bands (see Figure 2).

18 18 Figure 2. Typical half-mask respirator (NIOSH, 1987). Loose-fitting positive pressure respirators cover the head completely and form a partial seal with the face. Due to this partial seal sufficient air must be provided to maintain a positive-pressure which will cause an outward flow of air from the respirator that will prevent contaminants from entering the breathing zone. 2.3 Elements in an Effective Respiratory Protection Program The degree of protection provided by a respirator is dependent upon proper selection, fit testing, maintenance, and training. Respirators can only provide adequate protection if they are properly donned and worn consistently. A comprehensive respiratory protection program is essential in controlling these variables. OSHA 29 CFR

19 (b) (1-11) (1998) states the minimum acceptable requirements for a respiratory protection program. 1. Written standards operating procedures 2. Respirators selected on the basis of the hazard to which they are exposed 3. User shall be instructed and trained in proper use and limitations 4. Where practical, respirator assigned to individual worker 5. Respirator shall be regularly cleaned and disinfected 6. Respirator shall be stored in a convenient, clean and sanitary location 7. Respirators shall be inspected during cleaning 8. Appropriate surveillance of work area conditions 9. Regular inspections and evaluations of program 10. Medical review prior to use and annually 11. Use of certified respirators The respiratory standard also requires that an individual who has been appropriately trained and/or has experience in the proper selection, use, and maintenance of respirators administer the respiratory protection program. 2.4 Respirator Selection Respirator selection is an important factor in protecting the worker from occupational exposure to airborne contaminants. Selecting the wrong respirator is a common and significant mistake. The wrong type of respirator can give the employee a false sense of security, which can lead to high levels of exposure. When selecting a respirator it is essential to match the respirator to the hazard, the degree of the hazard

20 20 present, and the person using the equipment. Respirator selection is a complex task and should only be performed by an Industrial Hygienist or another individual who is knowledgeable in the limitations associated with each class of respirator. In addition, the actual work environment where the respirators will be worn must also be taken into account. When selecting a respirator the OSHA Technical Manual Section VII: Chapter 2 Respiratory Protection states that the following must be considered: 1. Nature of the hazard, and the physical and chemical properties of the air contaminant. 2. Concentrations of contaminants. 3. Relevant permissible exposure limit or other occupational exposure limit. 4. Nature of the work operation or process. 5. Time period the respirator is worn. 6. Work activities and physical/psychological stress. 7. Fit testing. 8. Physical characteristics, functional capabilities and limitations of respirators. In 1975, NIOSH and OSHA developed a guide for selecting respirator protection. This guide is commonly referred to as the Respirator Decision Logic, which consists of a set of questions that will systematically lead the user to the appropriate respiratory protection see Appendix A. The Respirator Decision Logic has been updated since its creation in 1975 as new information on respirator protection has been discovered. The NIOSH Guide to Respiratory Protection (1987) now includes the following modifications

21 21 to the Respirator Decision Logic, the NIOSH respirator carcinogen policy, respiratory protective devices developed since 1975, and a revision of assigned protection factors for those respirators for which valid workplace protection factor studies had been performed. Additionally, NIOSH has developed a guide for the selection and use of particulate respirators certified under 42 CFR 84. This new set of regulations (Part 84) applies to the testing and certification of non-powered, air purifying, particulate filter respirators. This new regulation has a much more stringent certification process than the old respirator regulation of 30 CFR 11. Part 84 categorizes filters according to filter efficiency and resistance to filter efficiency degradation. Filter efficiency is noted as 95%, 99% and 99.97%. Simply stated, filter efficiency is the percentage of particles removed from the air. The categories of resistance to filter efficiency degradation are labeled N, R, and P. The selection of N, R, or P filters is based upon the presence or absence of oil particles. N-type filters are not resistant to oil. R-type filters are resistant to oil, and P-type filters are oil proof. Filter efficiency degradation can be defined as a reduction in the ability of the filter to remove contaminants as a result of workplace use. Due to the implementation of part 84, a new decision logic is required for the selection of respiratory protection. This new decision logic is in Section II of the NIOSH guide to the selection and use of particulate respirators certified under 42 CFR 84 (see Appendix B). Proper respirator selection is very important; however, other variables such as respirator fit and consistent wearing of the respirator in the contaminated environment must occur for adequate protection of the worker.

22 Fit Testing Fit testing is essential to protect workers from occupational exposure. If a negative pressure respirator does not form a seal between the mask and the wearer s face the respirator will not adequately protect the worker. The OSHA Technical Manual Section VII: Chapter 2 Respiratory Protection states; The primary purpose of fit testing is to identify the specific make, model, style, and size of respirator best suited for each employee. In addition, fit testing also provides an opportunity to check on problems with respirator wear, and reinforces respirator training by having wearers review the proper methods of donning and wearing the respirator. OSHA CFR regulations on fit testing procedures states that; Every respirator wearer shall receive fitting instructions including demonstrations and practice in how the respirator should be worn, how to adjust it, and to determine if it fits properly. (See Appendix C.) Over the years numerous methods of fit testing have been developed. These methods can be categorized into two general groups: Qualitative Fit Testing (QLFT) and Quantitative Fit Testing (QNFT) Qualitative Fit Testing The procedure for qualitative fit testing involves the introduction of a gas, vapor, or aerosol test agent into the area surrounding the head. When exposed the individual wearing the respirator must determine if he/she can detect the presence of the test agent inside the respirator. If the test agent is detected the respirator does not fit adequately. OSHA currently has four qualitative fit protocols that involve test agents. Individuals

23 23 who are going to be fit tested with test agents must first undergo a sensitivity test to determine if they can taste, smell, or react to the substance. One test is the isoamyl acetate vapor test (IAA), more commonly known as the banana oil test. The chemical isoamyl acetate has a pleasant odor that is easily detectable. The most common method used in the IAA test is to saturate a piece of cotton or cloth with isoamyl acetate and pass it close to the sealing surfaces of the respirator. There are two major drawbacks to the IAA test. The first is that the odor threshold for isoamyl acetate varies widely among individuals. The second is that the sense of smell is easily deteriorated during the test. Similar tests are performed with saccharin and Bitrex TM. Another qualitative test is the irritant smoke test. The irritant smoke test is very similar to the IAA test. The irritant smoke test is performed by exposing the respirator wearer to an irritating aerosol. Common irritating aerosol agents are stannic chloride and titanium tetrachloride. This test has an advantage over the IAA test due to the involuntary reaction of coughing and sneezing when leakage occurs. The drawback of the irritant smoke test is that the smoke is highly irritating so proper safeguards must be taken to protect the tester as well the individual being tested Quantitative Fit Testing In quantitative fit testing, respirators are assessed by a numerical measurement that reflects the amount of leakage into the respirator.

24 24 Quantitative fit test can be performed in a number of ways: 1. Generated test aerosol 2. Ambient aerosol 3. Controlled negative pressure Generated Test Aerosol QNFT A quantitative fit test with a generated test aerosol is conducted inside a special chamber, which contains the artificially generated atmosphere. Test aerosols must be easily detectable and nontoxic. During this type of fit test the wearer is fitted with a respirator that has been modified with a special attachment port that allows the air inside the mask to be analyzed by a test instrument. This modified port is located between the respirator filter attachment port and the filter. Quantitative fit test adapters will be further discussed in the materials and methods section of this thesis. The respirator must be equipped with a particulate filter capable of preventing penetration of ambient particles used in the fit test. The advantage of the attachment port is that the wearer can be fit tested with the respirator he/she will be wearing in the workplace. The results of the test are expressed numerically as the concentration of the test agent outside the mask divided by the concentration of the test agent inside the mask Ambient Aerosol QNFT The ambient aerosol QNFT is very similar to the generated test aerosol QNFT; however, the ambient aerosol test does not require a chamber because it uses the particles in the ambient air. The ambient aerosol QNFT was one of the methods employed in this thesis. TSI Inc. St. Paul, Minnesota has developed the Portacount, which is an ambient

25 25 aerosol condensation nuclei counter. The theory of operation and methods of testing are discussed in detail in the materials and methods section of this thesis Controlled Negative Pressure (CNP) QNFT The controlled negative pressure QNFT is an alternative to traditional aerosol QNFT methods. The controlled negative pressure method uses air as the challenging agent. In a CNP QNFT air is temporarily exhausted from the respirator facepiece to generate and maintain a constant negative pressure. This exhaust rate is maintained during the test portion of the fit test. The level of negative pressure is selected to imitate the mean inspiratory pressure during inhalation. This level of pressure is called the challenging pressure and is based upon factors that are discussed in detail in the materials section of this thesis. When the pressure is held constant the air flow into the respirator is equal to air flow out of the respirator. Therefore, measurement of the exhaust stream is equal to leakage into the respirator. Occupational Health Dynamics Inc., Birmingham, Alabama is the manufacturer of the Fit Tester 3000, a controlled negative pressure quantitative fit testing device. The theory of operation and methods of testing will be discussed in detail in the materials and methods section of this thesis. 2.6 Fit Checking Fit checking is a simple yet effective way to determine if the respirator is obtaining a seal. Every time the respirator is donned the wearer should perform fit checking. The first check is the negative pressure test, which consist of closing the inlets of the respirator by covering the filters with the palms of the hands. The next step is to

26 26 inhale slowly causing the facepiece to collapse and hold for ten seconds. If the facepiece remains collapsed and no leakage is detected the respirator has passed the test. The second fit check is the positive pressure test, which is very similar to the negative pressure test. This test is performed by sealing off the exhalation valve and slowly exhaling into the mask creating a slight positive pressure. If the respirator has an outward leakage the respirator has not passed the test. Positive and negative pressure test should only be used in the following situations: 1. To determine gross fit; and 2. Determine if the respirator is sealed properly prior to entering a toxic atmosphere. Fit checking cannot take the place of qualitative or quantitative fit test. Workers must be fit tested by an OSHA approved method before using respiratory protective devices in the workplace. The purpose of fit checking is to simply verify that the respirator has an adequate seal. 2.7 Literature Research Traditionally quantitative fit tests have utilized polydispersed aerosols of oil, sodium chloride, or ambient particles. Various studies have been performed to examine the accuracy of aerosol QNFT. Researches have found that aerosol QNFT are biased by various factors, which include lung deposition, sampling conditions, aerosol size distribution, and aerosol in-mask mixing problems. When aerosols are not uniformly mixed inside the facepiece an overestimation of respirator fit is reported due to the undersampling of aerosol penetration.

27 27 A study by Myers et al. (1986) was conducted to provide an assessment of whether certain parameters of the man respirator system may introduce bias into infacepiece sampling. This study was based upon comparing a theoretical value to actual in-facepiece samples. The theoretical value was based upon tidal volume, respiratory minute volume, breathing frequency, and the concentration of the challenging agent outside the respirator. Myers et al. (1986) concluded that aerosol QNFT is dramatically biased by streamlining within the respirator cavity during inhalation. Streamlining is when aerosols are carried away from the sampling probe by strong drafts crated during the inhalation phase of respiration. This study found an observed sampling bias of aerosol QNFT ranged from 99% to +98% with a mean sampling bias of 17%. The findings of this study challenge the credibility of aerosol QNFT. Researchers have been working on an alternative method of QNFT that does not have the inherent problems associated with aerosol QNFT. The method that was developed is known as the controlled negative pressure QNFT. The controlled negative pressure QNFT is conceptually based on the negative pressure fit check, which measures leakage by the airflow coming into the mask when negative pressure is generated inside the facepiece by inhalation with the filters obstructed. Crutchfield et al. (1994) state that: The development of a quantitative respirator fit test method based on the controlled negative pressure (CNP) provides an alternative to standard aerosol fit test methods that is faster and less dependent on ambient test conditions. Several studies conducted by various researchers have found that the CNP method consistently produces lower fit factors than those given by aerosol fit testing methods. Researchers have concluded that

28 28 the CNP method is a more accurate method of fit testing because it is capable of detecting a far greater percentage of the leaks that are present. Cruchfield et al. (1995) validated this by performing a study that compared the Portacount to the Fit Tester 3000 in conditions of known respirator leakage. The study consisted of five subjects who were fit tested 15 on each machine over three weeks. Each subject was assigned a respirator with a specific leak needle. The leak locations were the bridge of the nose, cheek, and chin. The objectives of this study were: 1. To determine how well each system measured the leakage 2. To determine if leak location affects leak measurement The study conducted by Crutchfield et al. (1995) concluded that: The ambient aerosol system detected an overall average of 37.2% of the known leakage, with a coefficient of variation of 44.7%. An analysis of variance showed significant differences in aerosol system measurements of leakage as a function of leak location The CNP system detected an overall average of 97.9% of the known leakage, with a coefficient of variation of 4.3%. The CNP system results were not affected by leak location. A study conducted by Oestenstad and Graffeo (1994) comparing CNP to the ambient aerosol method found similar results to those found by Crutchfield et al (1994). This study conducted by Oestenstad and Graffeo (1994) consisted of replicated fit tests on 15 male subjects who wore one size of four different brands or respirators. Each subject was fit tested three times by each machine while wearing each brand of respirator for a total of 180 fit test. Oestenstad and Graffeo (1994) concluded that the fit factors measured by the CNP method were significantly lower that those measured by traditional

29 29 aerosol methods. This study also found that the geometric mean of fit factors for the aerosol methods was15 times than those generated by the CNP method. Another interesting observation made by Oestenstad and Graffeo (1994) was that during testing two subjects were not able to achieve measurable fit factor with the CNP while achieving fit factors greater than 3200 with the aerosol method. The conclusion of Oestenstad and Graffeo s study is that the CNP and the aerosol methods are not highly correlated.

30 MATERIALS The materials section of this thesis will explain the theory of operation for the Portacount Plus Model 8020 and the Fit Tester Quantitative fit test adapters for both devices will also be covered. 3.1 Portacount Plus 8020 Quantitative Fit Test Instrument The Portacount Plus 8020 is an ambient aerosol quantitative fit test device that is used to numerically evaluate the seal between the respirator sealing surface and the face of the respirator wearer. This numerical evaluation produces a fit factor and is based upon the ratio of the concentration of particles outside the respirator to the concentration of particles that have leaked into the respirator during the fit test. Fit Factor = Outside Concentration/ Inside Concentration The Portacount is equipped with two sampling tubes, one of the tubes samples the ambient air and the other samples the air inside the respirator cavity. A valve located inside the instrument switches back and fourth between the ambient air tube and the mask space according to the following timing sequence. All exercises have a total duration of 80 seconds (See Table I) with the exception of the grimace exercise, which has a duration of 35 seconds (See Table II). Table I. Normal Exercise Duration For the Portacount Plus Ambient purge Ambient sample Mask purge Mask sample Total Time 4 seconds 5 seconds 11 seconds 60 seconds 80 seconds

31 31 Table II. Grimace Exercise Duration For the Portacount Plus Ambient purge Ambient sample Mask purge Mask sample Total Time 4 seconds 5 seconds 11 seconds 15 seconds 35 seconds The Portacount Plus uses continuous-flow Condensation Nuclei Counter (CNC) technology to convert submicrometer particles that are too small to be detected to larger more easily detectable supermicrometer alcohol droplets, which are then subsequently counted. The concept of CNC has been around since 1888, however TSI Inc. developed the first portable continuous-flow CNC. The Portacount Plus creates supermicrometer alcohol droplets by the following steps: 1. Submicrometer particles are drawn into the instrument via a diaphragm pump at 0.7 liter per minute. 2. The flow is split at the saturator end cap where 0.1 liters per minute enters the saturator and 0.6 liters per minute is diverted to the excess airline, which is later recombined with the sampled flow on the other side of the counting detector area. 3. The saturator is lined with an alcohol-soaked wick that causes the aerosol to be saturated with alcohol vapor (a thermoelectric device heats the saturator). 4. The aerosol now passes through the condenser where the aerosol grows into droplets (a thermoelectric device cools the condenser). 5. The droplets then pass through a nozzle and into the detector area.

32 32 6. The detector area consists of a laser light source, focussing optics, receiving optics, and a photodetector. Each time a particle passes through the detector area the laser light is scattered. This scattered light is collected by the receiving optics and focused onto the photodetector, which generates an electrical pulse. The particle count is directly related to the number of electrical pulses. Particle count (number of electrical pulses), time period, and flowrate are used by the Portacount Plus to determine particle concentration. See Figure 3 for a schematic diagram of the Portacount Plus. Figure 3. Schematic of PortaCount Plus (PortaCount Plus Operation and Service Manual, 1996).

33 Fit Tester 3000 Quantitative Fit Test Instrument The Fit Tester 3000 uses controlled negative pressure technology to determine the fit factor, which is a numerical evaluation of the face-to-facepiece fit of a respirator. As mentioned previously the Portacount and the Fit Tester 3000 determine fit factors in two entirely different ways. The Fit Tester 3000 s fit factor is equivalent to fit factors obtained by traditional quantitative fit test methods. The fit factor for the Fit Tester 3000 is the ratio of the modeled breathing rate to the measured leak rate. The modeled breathing rate is equivalent to the concentration outside the mask, and the measured leak rate is equivalent to the concentration inside the mask. Fit Factor = Modeled Breathing Rate/ Measured Leak Rate FF = Modeled Breathing Rate = Concentration Outside Mask Measured Leak Rate Concentration Inside Mask Modeled breathing rate is defined in the Fit Tester 3000 Operating and service Manual (1996) as, The rate, in liters per minute, at which an individual breathes, and is calculated from the parameters specified by the operator for each protocol or fit test. The operator-specified parameters are inspiratory work rate, respirator mask type, cartridge type, and test subject s gender. Modeled breathing rate is used to calculate challenging pressure. Challenging pressure is the negative pressure that would be produced by an individual wearing a respirator during inhalation. Challenging pressure is measured in hundredths of an inch of water. The first parameter is inspiratory work rate, which has the largest influence on internal respirator mask pressure. When an individual works harder he/she expends more energy, which causes an increase in the amount of oxygen consumption. This increased

34 34 oxygen consumption results in an increased volume of airflow through the respirator filter, which results in a higher internal negative pressure inside the respirator mask. The most common unit for the measurement of physical activity is the Kcal. A Kcal by definition is the amount of energy required to raise 1000 grams of water 1 degree C. The operator of the fit test must estimate the normal work rate the test subject experiences under typical working conditions. The Fit Tester 3000 has the following categories: light, moderate, heavy, and extreme that are listed below in Table III. Table III. Work Rate Categories For the Fit Tester Kcal/hr Light Standing still or sitting at ease 200 Kcal/hr Moderate Walking without a load 300 Kcal/hr Heavy Walking with or moving a light load 400 Kcal/hr Extreme Walking with or moving a heavy load, climbing stairs, digging, etc The second parameter is mask type. The choices are full face or half mask. The reason for the distinction is due to the carbon dioxide accumulation in the dead space of the full face respirator, which causes the subject to breath harder and deeper to compensate for the lower oxygen content present in the mask. Harder and deeper breaths mean higher negative pressure inside the mask. The third parameter is the type of cartridge used in conjunction with the respirator. Cartridges are classified into four general categories according to the Fit Tester operations and service manual (see Table IV).

35 35 Table IV. Cartridge Resistance Categories For the Fit Tester Low Medium High N/A Dust/Mist Filter Chemical or HEPA Combination of Chemical and HEPA Respirator mask that do not use cartridges; for example, SCBA and PAPR Negative pressure inside the mask is directly related to cartridge resistance (breathing resistance); therefore, a higher-density more resistive cartridge will cause a greater negative pressure within the mask. The fourth and final parameter is gender. The volume of air breathed in at a given work rate is the same for males and females; however, inhalation rates vary. In general males inhale faster then females. This increased inhalation rate causes a higher instantaneous flow rate, which results in a higher negative pressure. The denominator in the fit factor equation for the Fit Tester 3000 is measured leak rate. Measured leak rate is directly related to facepiece fit and is measured in cubic centimeters per minute (cc/min). Measured leak rate is determined by performing a fit test and is a measurement of how much air is removed from the respirator mask after the challenging pressure has been established. A micro-sampling pump or piston located inside the Fit Tester 3000 is controlled by a pressure transducer that allows air to be pulled out of the mask until a predetermined negative pressure is established. A mass flow meter measures the volume of air exhausted to maintain that pressure. The volume of air exhausted is the measured leak rate.

36 Quantitative Fit Test Adapter for the Portacount Plus The quantitative fit test adapter used with the North 7700 half-mask respirator is simply screwed into the cartridge receptacle of the respirator. The adapter is threaded on both ends, which allows the filter to be attached to the other end of the adapter. The sampling tube is then placed inside the mask and held in place by a small suction cup. A barbed fitting on the adapter body allows for a connection to be made between the sampling tube inside the mask and the Portacount Plus. Installation instructions are found in Appendix D. 3.4 Quantitative Fit Test Adapters for the Fit Tester 3000 There are two adapters that are used with the Fit Tester The inhalation valves of the adapted respirator must be removed or propped open for the CNP fit test to work properly. One of the adapters is the squeeze-bulb assembly. The squeeze-bulb assembly is screwed into the cartridge receptacle of the respirator. The squeeze-bulb assembly is equipped with an airtight manifold that is pneumatically controlled. When the squeeze-bulb is compressed the manifold is activated, which seals off the respirator allowing a negative pressure to be established. When the squeeze-bulb is released the airtight manifold is deactivated creating a breathing path for the test subject. The second adapter that is used with the Fit Tester 3000 is the dual tube assembly connection. The dual tube assembly connection is also screwed into the cartridge receptacle of the respirator. The dual tube assembly connection has two ports. One port monitors the pressure inside the respirator mask and the other port removes air from the

37 37 respirator mask at a controlled rate. These ports are connected to the dual tube assembly on the Fit Tester 3000 via tubing.

38 METHODS This section covers prescreening of test subjects, Portacount Plus daily calibration, Fit Tester 3000 daily calibration, OSHA protocol Portacount, OSHA protocol Fit Tester 3000, Modified protocol Portacount, Modified protocol Fit Tester 3000, and statistical analysis. 4.1 Prescreening of Test Subjects The subjects in this study were limited to ten males and ten females between the ages of 18 and 55 years of age. Test subjects were also required to have no facial hair where the sealing surface of the respirator contacted the face. Prior to any fit checking and quantitative fit testing the subjects were fully briefed and trained on the use of half-mask respirators. The subjects were also briefed on the steps and protocol used to conduct the fit test. The individuals were also shown how to properly don and doff the respirators used in this study. The test subjects were educated in all areas of concern according to ANSI Z The sequence of testing by protocol and instrument was randomized by the blind selection of labeled cards. Each protocol and its corresponding instrument were designated with a number. The OSHA protocol Portacount was selected as number one, the OSHA protocol Fit Tester 3000 as number two, the Modified protocol Portacount as number three, and the Modified protocol Fit Tester 3000 as number four. The test subjects randomly chose three cards with the remaining card being selected by default. Each test subject was fit tested four times. There were twenty subjects for a total of eighty fit tests. Respirators were doffed and donned between each fit test.

39 39 Respirator sizes were selected on the basis of the subject s perception of which size fit best, and confirmed by positive and negative pressure fit checks, and the ability to achieve a minimum fit factor of 100 on the first fit test performed. In the event of a test subject failing to achieve a minimum fit factor of 100, the test subject was fitted with another size respirator. Test subjects unable to attain a minimum fit factor of 100 on any of the four fit tests were not counted in the study. Prior to any quantitative fit testing the subjects were asked a number of descriptive questions that were entered into the sample data sheet according to the FitTrack software for the Fit Tester 3000, and the TSI FitPlus test software (see Appendix E). 4.2 Portacount Plus Daily Calibration The first step in operation of the Portacount Plus was performing two maintenance checks. The zero check and the maximum fit factor check, which were completed according to the Portacount Plus Operation and Service Manual (1996) (see Appendix F). 4.3 OSHA Protocol Portacount OSHA has a set of regulations for the official OSHA protocol used with the Portacount. This set of detailed instructions is listed in the OSHA Regulations for Fit Testing Procedures (Mandatory) 29 CFR Appendix A. The official OSHA protocol that the test subjects performed while wearing the adapted respirator as part of this study can be found in Appendix G. Listed below are the exercises performed by the subjects as part of the OSHA protocol for the Portacount.

40 40 1. Normal Breathing 2. Deep Breathing 3. Turning Head Side to Side 4. Moving Head Up and Down 5. Talking 6. Grimace 7. Bending Over 8. Normal Breathing 4.4 Fit Tester 3000 Daily Calibration There are two daily calibration checks that were completed before the Fit Tester 3000 was used. Those checks consist of the dual tube calibration and the zero pressure check. The zero pressure check removes the offset from the pressure transducer, and was performed by disconnecting the dual the assembly and pressing any key. The dual tube calibration must be conducted to accurately measure respirator fit. The leakage value from the dual tube assembly leak orifice must be accounted for and subtracted from the fit test leakage value. The dual tube calibration was performed by connecting the two quick-disconnect adapters on the dual tube assembly to the Fit Tester Press the enter key and the Fit Tester removed air at eight different flow rates. The pressure at the leak orifice was measured at each flow rate and stored. When the eight stages were completed the calibration was complete.

41 OSHA Protocol Fit Tester 3000 OSHA has also established a set of regulations governing the procedures that must be followed when using the OSHA protocol in conjunction with CNP QNFT. These regulations are also listed in the OSHA Regulations for Fit Testing Procedures (Mandatory) 29 CFR Appendix A. Prior to conducting fit tests with the Fit Tester 3000 the subjects were instructed and given the opportunity to complete several pretests to familiarize themselves with the proper procedure for holding their breath during the test measurement portion of the fit test. The test subjects were instructed to keep their mouth closed, not to exhale through their nose, and not to make any head or facial movements during the test measurement portion of the fit test protocol. The adapted OSHA protocol used for CNP QNFT that the test subjects performed while wearing the adapted respirator as part of this study can be found in Appendix H. The official OSHA protocol for the CNP was changed for comparison purposes. The OSHA protocol for the Fit Tester 3000 is the same as the OSHA protocol for the Portacount with the exception of added tests at the end of each exercise. 1. Normal Breathing (Test) 2. Deep Breathing (Test) 3. Turning Head Side to Side (Test Head Right\Test Head Left) 4. Moving Head Up and Down (Test Head Up\Test Head Down) 5. Talking (Test) 6. Grimace (Test) 7. Bending Over (Test)

42 42 8. Normal Breathing (Test) 4.6 Modified Protocol Portacount Crutchfield et al. (1999) has conducted research on the relative importance of fit test exercises and mask donning techniques on measured respirator fit. As a result of this research Crutchfield et al. (1999) has developed a condensed or modified fit test protocol that is based upon fewer, more targeted exercises that are as effective at identifying poorly fitting respirators as the current OSHA protocol. Before a QNFT was performed the subjects were briefed, and the instrument was calibrated. The Modified protocol used by the Portacount that was performed by the test subjects evaluated in this study can be found in Appendix I. Listed below are the exercises performed by the subjects as part of the Modified protocol for the portacount. 1. Fundamental Fit (Same as Normal Breathing) 2. Bending Over 3. Shake Head 4.7 Modified Protocol Fit Tester 3000 Crutchfield et al. (1999) also developed a modified QNFT protocol for the CNP method. The Modified protocol used by the Fit Tester 3000 that was performed by the test subjects evaluated in this study can be found in Appendix J. Listed below are the exercises performed by the subjects as part of the Modified protocol for the Fit Tester Fundamental Fit (Same as Normal Breathing) (Test) 2. Bending Over (Test in the Bent Over Position)

43 43 3. Shake Head 4.8 Statistical Analysis Methods The statistical program used to assess and analyze the data collected during this study was Minitab (Minitab Inc., 1998). The statistical programs used in Minitab were descriptive statistics, normality test, stacked and un-stacked One-Way Analysis of Variance (ANOVA), Tukeys Multiple Comparison Test, Two-Way ANOVA, and One- Sample t test.

44 RESULTS and DISCUSSION The raw data collected for this thesis can be found in Appendix K. A total of 80 fit tests were performed on ten male and ten female subjects. The data was first grouped by instrumentation and protocol. Summary statistics were also performed (see Table V). The observed results of the summary statistics showed that the Portacount overall fit factors are significantly higher than those of the Fit Tester Additionally, the standard deviation for the Portacount is much greater than that of the Fit Tester Table V. Summary Statistics of Fit Factors by Protocol and Instrumentation. Instrument Protocol N Mean SD 95% CI Portacount Modified Portacount OSHA Fit Tester 3000 Modified Fit Tester 3000 OSHA The data was then further grouped according by gender and summary statistics were performed (see Table VI). As mentioned earlier the overall fit factors and the standard deviation given by the Portacount is much greater than those given by the Fit Tester Furthermore, the difference between male and female overall fit factors is far greater using the Portacount for both the OSHA and Modified protocols. An interesting observation of this study was that female subjects were much more difficult than male subjects to get a satisfactory fit between the respirator and the wearers face. A total of six females were unable to get an overall fit factor of 100 or better. For that reason they were not included in this study. Additionally, one male subject was excluded from this study due to the inability to get an overall fit factor of 100 or better.

45 45 Table VI. Summary Statistics of Fit Factors by Protocol, Instrumentation, and Gender. Instrument Protocol Gender N Mean SD 95% CI Portacount Modified M Portacount Modified F Portacount OSHA M Portacount OSHA F Fit Tester 3000 Modified M Fit Tester 3000 Modified F Fit Tester 3000 OSHA M Fit Tester 3000 OSHA F The data was then log transformed due to the large differences in standard deviations between the two machines. The large standard deviations associated with the overall fit factors in this study are due to the inherent variability that is encountered when using multiple human subjects. The log transformed data and normality test can be found in Appendix L. 5.1 Machine Comparisons One-Way Analysis of Variance (ANOVA) was conducted on log transformed data in order to determine the presence of a significant difference between the overall fit factors given by the Fit Tester 3000 and the Portacount using the same protocol. The results of the One-Way ANOVA showed a significant difference between the overall fit factors given by the Fit Tester 3000 and the Portacount using the OSHA protocol. A P-value of shows that the difference between the Fit Tester 3000 and the Portacount using the OSHA protocol is highly significant (see Figure 4). The Fit Tester 3000 consistently gives overall fit factors that are lower than those produced by the Portacount.

46 46 One-way Analysis of Variance Analysis of Variance Source DF SS MS F P Factor Error Total Individual 95% CIs For Mean Based on Pooled StDev Level N Mean StDev OSHA (---*----) OSHA Portacount (----*----) Pooled StDev = Figure 4. Results of ANOVA on the Fit Tester And the Portacount Using the OSHA Protocol. Further, results using One-Way ANOVA revealed that the overall fit factors given by the Fit Tester 3000 using the Modified protocol were consistently lower than those given by the Portacount using the Modified protocol. These finding are in agreement with the results of the OSHA protocol using both machines. A P-value of shows that the difference between the Fit Tester 3000 and the Portacount using the Modified protocol is highly significant (see Figure 5). The lack of uniformity between the two machines may be due to lung deposition, sampling conditions, aerosol size distribution, and aerosol in-mask mixing problems.

47 47 One-way Analysis of Variance Analysis of Variance Source DF SS MS F P Factor Error Total Individual 95% CIs For Mean Based on Pooled StDev Level N Mean StDev Modified Portacount (-----*-----) Modified (-----*------) Pooled StDev = Protocol Comparisons Portacount Figure 5. Results of ANOVA on the Fit Tester 3000 and the Portacount Using the Modified Protocol. One-Way ANOVA was also performed to find out if there was a significant difference between the Modified and the OSHA protocols using the Portacount (see Figure 6). A P-value of.430 indicates that there is no significant difference between the Modified and the OSHA protocols using the Portacount. The Modified protocol appears to be as stringent as the OSHA protocol using the Portacount. More data may be necessary to have greater confidence in these findings. The advantage of the modified protocol is that respirator fit can be evaluated with fewer exercises and thus take less time. General industry would be in favor of this method due to the decrease in time required to perform fit testing. Regulating agencies may also accept this new protocol due to the fact that it is as stringent as the OSHA protocol.

48 48 One-way Analysis of Variance Analysis of Variance Source DF SS MS F P Factor Error Total Individual 95% CIs For Mean Based on Pooled StDev Level N Mean StDev Modified Portacount ( * ) OSHA Portacount ( * ) Pooled StDev = Figure 6. Results of ANOVA on the Portacount comparing Modified and OSHA Protocol. 5.3 Protocol Comparisons Fit Tester 3000 Additional one-way ANOVA analysis was performed on the Fit Tester 3000 data comparing the Modified and OSHA protocols (see Figure 7). One-Way ANOVA results gave a P-value of.424, which depicts no significant difference between the Modified and OSHA protocols using the Fit Tester These results are in agreement with those found earlier, which gives further confidence that the Modified protocol may be as stringent as the OSHA protocol.

49 49 One-way Analysis of Variance Analysis of Variance Source DF SS MS F P Factor Error Total Individual 95% CIs For Mean Based on Pooled StDev Level N Mean StDev Modified ( * ) OSHA ( * ) Pooled StDev = Figure 7. Results of ANOVA on the Fit Tester 3000 comparing Modified and OSHA Protocol. 5.4 Gender Comparisons for the Portacount Using the Modified Protocol One-Way ANOVA was performed to determine if there is a significant difference between Male and Female overall fit factors measured by the Portacount using the Modified protocol (see Figure 8). The results of the analysis gave a P-value of.528, which means that there is not a significant difference between Male and Female overall fit factors measured by the Portacount using the Modified protocol. Female subjects are harder to fit, but statistical analysis shows that respirator fit is not biased by gender.

50 50 One-way Analysis of Variance 1=Male Modified Portacount 2=Female Modified Portacount Analysis of Variance for Stacked Source DF SS MS F P Code Por Error Total Individual 95% CIs For Mean Based on Pooled StDev Level N Mean StDev ( * ) ( * ) Pooled StDev = Figure 8. Results of ANOVA for the Portacount comparing Male and Female overall fit factors using the Modified Protocol. 5.5 Gender Comparisons for the Portacount Using the OSHA Protocol One-Way ANOVA was performed to determine if there is a significant difference between Male and Female overall fit factors measured by the Portacount using the OSHA protocol (see Figure 9). The results of the analysis gave a P-value of.260, which means that there is not a significant difference between Male and Female overall fit factors measured by the Portacount using the OSHA protocol.

51 51 One-way Analysis of Variance 3=Male OSHA Portacount 4=Female OSHA Portacount Analysis of Variance for Stacked Source DF SS MS F P Code Por Error Total Individual 95% CIs For Mean Based on Pooled StDev Level N Mean StDev ( * ) ( * ) Pooled StDev = Figure 9. Results of ANOVA for the Portacount comparing Male and Female overall fit factors using the OSHA Protocol. 5.6 Gender Comparisons for the Fit Tester 3000 Using the Modified Protocol One-Way ANOVA was also performed to determine if there is a significant difference between Male and Female overall fit factors measured by the Fit Tester 3000 using the Modified protocol (see Figure 10). The analysis produced a P-value of.391 for the One-Way ANOVA, which means that there is no significant difference between the overall fit factors given to Male subjects by the Fit Tester 3000 using the Modified protocol then given to Female subjects.

52 52 One-way Analysis of Variance 5=Male Modified =Female Modified 3000 Analysis of Variance for Stacked Source DF SS MS F P Code Error Total Individual 95% CIs For Mean Based on Pooled StDev Level N Mean StDev ( * ) ( * ) Pooled StDev = Figure 10. Results of ANOVA for the Fit Tester 3000 comparing Male and Female Overall fit factors using the Modified Protocol. 5.7 Gender Comparisons for the Fit Tester 3000 Using the OSHA Protocol Finally, One-Way ANOVA was performed to determine if there is a significant difference between Male and Female overall fit factors measured by the Fit Tester 3000 using the OSHA protocol (see Figure 11). The analysis produced a P-value of.824 for the One-Way ANOVA, which means that there is no significant difference between the overall fit factors given to Male subjects as compared to Female subjects by the Fit Tester 3000 using the OSHA protocol.

53 53 One-way Analysis of Variance 7=Male OSHA =Female OSHA 3000 Analysis of Variance for Stacked Source DF SS MS F P Code Error Total Individual 95% CIs For Mean Based on Pooled StDev Level N Mean StDev ( * ) ( * ) Pooled StDev = Figure 11. Results of ANOVA for the Fit Tester 3000 comparing Male And Female overall fit factors using the OSHA Protocol. 5.8 Additional Statistical Analysis Some additional statistical analysis was performed to explore the interaction of overall fit factors for each machine. Two-Way ANOVA was performed using the natural log (lnff) of the overall fit factors versus block, machine, and protocol. The results of the Two-Way ANOVA revealed that a P-value of for machine interaction, and a P- value of.255 for protocol interaction (see Table VII). The P-value of for machine interaction means that there is a highly significant difference between the two machines See Appendix M for plot of ff vs. machine. The P-value of for the protocol interaction verifies earlier analyses by indicating that there is no significant difference between the protocol. See Appendix N for plot of ff vs. protocol.

54 54 Table VII. Results of Two-Way ANOVA lnff vs. Block, Machine, Protocol. ANOVA: lnff versus block, machine, protocol Factor Type Levels Values block fixed machine fixed protocol fixed Analysis of Variance for lnff Source DF SS MS F P block machine protocol machine*protocol Error Total Discussion This study found that the overall fit factors obtained by the pressure-based system of the Fit Tester 3000 were significantly lower than those obtained by the particle-based system of the Portacount. Additionally, the standard deviation for the Portacount was found to be much greater than that of the Fit Tester The dramatic differences between the two methods may be due to aerosol streamlining and other biases associated with Condensation Nuclei Counter (CNC) technology. Another observation that can be drawn from this study is that the Controlled Negative Pressure (CNP) method provides a more conservative measure of respirator fit. These findings were in agreement with Cruchfield et al. (1995) and Oestenstad and Graffeo (1994).

55 55 Additionally, this study compared the OSHA protocol to the modified protocol for both the Fit Tester 3000 and the Portacount. The modified protocol targets specific exercises that have the greatest impact upon respirator fit. Upon analyzing the data collected for this study the modified protocol appears to be as effective as the OSHA protocol in evaluating respirator fit in fewer exercises. Finally, this study explored gender comparison with regard to respirator fit. This study concluded that gender does not effect respirator fit; however, the sample size for gender comparison was relatively small and may not be accurate. Further, research is necessary to have more confidence in these findings. In general females are more difficult to fit than males due to smaller facial features and shorter bridge of the nose to bottom of the chin distance.

56 CONCLUSION The results of the statistical analyses performed in this thesis provide the necessary information to reject or to fail to reject the eight null hypotheses investigated. The conclusions from this study are as follows: 1. Null Hypothesis #1 stated that the overall fit factors obtained by the Fit Tester 3000 would not be significantly different than the overall fit factors obtained by the Portacount using the OSHA protocol. One-Way ANOVA provided evidence that there is a significant difference between the overall fit factors given by the Fit Tester 3000 and the Portacount using the OSHA protocol. Null Hypothesis #1 is rejected. 2. Null Hypothesis #2 stated that the overall fit factors obtained by the Fit Tester 3000 would not be significantly different than the overall fit factors obtained by the Portacount using the Modified protocol. One-Way ANOVA provided evidence that there is a significant difference between the overall fit factors given by the Fit Tester 3000 and the Portacount using the Modified protocol. Null Hypothesis #2 is rejected. 3. Null Hypothesis #3 stated that the overall fit factors obtained by the Portacount using both the OSHA and Modified protocols would not be significantly different. One-Way ANOVA confirmed that there is not a significant difference between the overall fit factors given by the Portacount using the OSHA and Modified protocols. Fail to reject Null Hypothesis #3.

57 57 4. Null Hypothesis #4 stated that the overall fit factors obtained by the Fit Tester 3000 using both the OSHA and Modified protocols would not be significantly different. One-Way ANOVA confirmed that there is not a significant difference between the overall fit factors given by the Fit Tester 3000 using the OSHA and Modified protocols. Fail to reject Null Hypothesis #4 5. Null Hypothesis #5 stated that overall fit factors obtained by male subjects using the Portacount with the Modified protocol would not be significantly different than the overall fit factors obtained by female subjects using the Portacount with the Modified protocol. One-Way ANOVA confirmed that there is not a significant difference between male and female overall fit factors given by the Portacount using the Modified protocol. Fail to reject Null Hypothesis #5. 6. Null Hypothesis #6 stated that overall fit factors obtained by male subjects using the Portacount with the OSHA protocol would not be significantly different than the overall fit factors obtained by female subjects using the Portacount with the OSHA protocol. One-Way ANOVA confirmed that there is not a significant difference between male and female overall fit factors given by the Portacount using the OSHA protocol. Fail to reject Null Hypothesis #6. 7. Null Hypothesis #7 stated that overall fit factors obtained by male subjects using the Fit Tester 3000 with the Modified protocol would not be significantly different than the overall fit factors obtained by female subjects

58 58 using the Fit Tester 3000 with the Modified protocol. One-Way ANOVA confirmed that there is not a significant difference between male and female overall fit factors given by the Fit Tester 3000 using the Modified protocol. Fail to reject Null Hypothesis #7. 8. Null Hypothesis #8 stated that overall fit factors obtained by male subjects using the Fit Tester 3000 with the OSHA protocol would not be significantly different than the overall fit factors obtained by female subjects using the Fit Tester 3000 with the OSHA protocol. One-Way ANOVA confirmed that there is not a significant difference between male and female overall fit factors given by the Fit Tester 3000 using the OSHA protocol. Fail to reject Null Hypothesis #8

59 Recommendations for Further Research This research covers only a fraction of the possibilities that are available for study on this topic. Listed below are recommendations for further research. 1. Perform this same study using other protocols. (e.g., asbestos, cadmium, lead.) 2. Perform this same study using other brands of half-mask respirators. 3. Perform this same study using full-face respirators. 4. Perform this same study, but increase the sampling size for Gender Comparisons. 5. Perform a similar study comparing the Fit Tester 3000 ReDon protocol to three consecutive fit tests using the Portacount. 6. Develop a non-hazardous fibrous challenging agent for fit testing workers who rely on respiratory protection (i.e. respirators) to protect them from hazardous airborne fibrous material. One must consider that the behavior of fibers is extremely different than that of particles. 7. Perform a study using the Fit Tester 3000 in an actual workplace. The study would consist of taking a fit test before the beginning of the shift, at several intervals within the work shift, and at the end of the work shift to determine if respirator fit deteriorates during workplace activities.

60 60 REFERENCES American National Standards for Respiratory Protection. Z (1992) American National Standards Institute: New York. Crutchfield, C., Ruiz, A., Ert, M. (1994). A Validation Study of Respirator Fit Testing by Controlled Negative Pressure. Applied Occupational and Environmental Hygiene, Crutchfield, C., Park, D., Hensel, J., Kvesic, M., Flack, M. (1995). Deteminations of Known Respirator Leakage Using Controlled Negative Pressure And Ambient Aerosol QNFT Systems. American Industrial Hygiene Association, Crutchfield, C., Park, D. (1997). Effect of Leak Location on Measured Respirator Fit. American Industrial Hygiene Association Journal, Crutchfield, C., Fairbank, E., Greenstein, S. (1999). Effect of Test Exercises and Mask Donning on Measured Respirator Fit. Applied Occupational and Environmental Hygiene, Code of Federal Regulations, 29. (1996) U.S. Government Printing Office: Washington, DC. Fit Testing Procedures (Mandatory) App A [data base online] Occupational Safety and Health Administration U.S. Department of Labor: [cited on 15 October 2000] Available: Lenhart, S. W., and Campbell, D.L., (1984). Assigned Protection Factors: Statistical Aspect of Its Definition and Implications for Risk Management. International Society for Respirator Protection Myers, W., Allender, J., Plummer, R., Stobbe, T. (1986). Parameters that Bias the Measurement of Airborne Concentrations Within a Respirator. American Industrial Hygiene Association Journal, National Institute for Occupational Safety and Health (NIOSH). (1987). Guide to Respiratory Protection. U.S.Government Printing Office:Washington, DC.

61 61 Oestenstad, R., Graffeo, B. (1994). Determination of Respirator Fit by an Aerosol Method and a Negative Pressure Method. Journal of the International Society for Respiratory Protection, OHD. (1997). Fit Tester 3000 Operating and Service Manual. Birmingham, AL. OSHA Technical Manual Section VIII: Chapter 2. Respiratory Protection [database online] Occupational Safety and Health Administration U.S. Department of Labor: [cited on 15 October 2000] Available: TSI. (1996). Portacount Plus Operation and Service Manual. Saint Paul, MN..

62 62 APPENDIX A Respirator Decision Logic

63 Flow Chart of Respirator Decision Logic Sequence 63

64 64 Flow Chart of Respirator Decision Logic Sequence (Continued) (Adapted NIOSH Guild to Industrial Respiratory Protection, 1987.)

65 65 APPENDIX B NIOSH Guide to the Selection and Use of Particulate Respirators Certified Under 42CFR 84

66 66 NIOSH Guide to the Selection and Use of Particulate Respirators Certified Under 42 CFR 84: 1. The selection of N-, R-, and P-series filters depends on the presence or absence of oil particles, as follows: If no oil particles are present in the work environment, use a filter of any series (i.e., N-, R-, or P-series). If oil particles (e.g., lubricants, cutting fluids, glycerine, etc.) are present, use an R-or P-series filter. Note: N-series filters cannot be used if oil particles are present. If oil particles are present and the filter is to be used for more than work shift, use only a P-series filter. Note: To help you remember the filter series, use the following guide: N for Not resistant to oil R for Resistant to oil P for oil-proof 2. Selection of filter efficiency (i.e., 95%, 99%, or 99.97%) depends on how much filter leakage can be accepted. Higher filter efficiency means lower filter leakage. 3. The choice of facepiece depends on the level of protection needed -- that is, the assigned protection factor (APF) needed.

67 67 APPENDIX C Fit Testing Procedures (General Requirements)

68 68 Fit Testing Procedures (General Requirements) The employer shall conduct fit testing using the following procedures. The requirements in this appendix apply to all OSHA-accepted fit test methods, both QLFT and QNFT. 1. The test subject shall be allowed to pick the most acceptable respirator from a sufficient number of respirator models and sizes so that the respirator is acceptable to, and correctly fits, the user. 2. Prior to the selection process, the test subject shall be shown how to put on a respirator, how it should be positioned on the face, how to set strap tension and how to determine an acceptable fit. A mirror shall be available to assist the subject in evaluating the fit and positioning of the respirator. This instruction may not constitute the subject's formal training on respirator use, because it is only a review. 3. The test subject shall be informed that he/she is being asked to select the respirator that provides the most acceptable fit. Each respirator represents a different size and shape, and if fitted and used properly, will provide adequate protection. 4. The test subject shall be instructed to hold each chosen facepiece up to the face and eliminate those that obviously do not give an acceptable fit. 5. The more acceptable facepieces are noted in case the one selected proves unacceptable; the most comfortable mask is donned and worn at least five minutes to assess comfort. Assistance in assessing comfort can be given by discussing the points in the following item A.6. If the test subject is not familiar with using a particular respirator, the test subject shall be directed to don the mask several times and to adjust the straps each time to become adept at setting proper tension on the straps. 6. Assessment of comfort shall include a review of the following points with the test subject and allowing the test subject adequate time to determine the comfort of the respirator: (a) Position of the mask on the nose (b) Room for eye protection (c) Room to talk

69 69 (d) Position of mask on face and cheeks 7. The following criteria shall be used to help determine the adequacy of the respirator fit: (a) Chin properly placed; (b) Adequate strap tension, not overly tightened; (c) Fit across nose bridge; (d) Respirator of proper size to span distance from nose to chin; (e) Tendency of respirator to slip; (f) Self-observation in mirror to evaluate fit and respirator position. 8. The test subject shall conduct a user seal check, either the negative and positive pressure seal checks described in Appendix B-1 of this section or those recommended by the respirator manufacturer which provide equivalent protection to the procedures in Appendix B-1. Before conducting the negative and positive pressure checks, the subject shall be told to seat the mask on the face by moving the head from side-to-side and up and down slowly while taking in a few slow deep breaths. Another facepiece shall be selected and retested if the test subject fails the user seal check tests. 9. The test shall not be conducted if there is any hair growth between the skin and the facepiece sealing surface, such as stubble beard growth, beard, mustache or sideburns which cross the respirator sealing surface. Any type of apparel which interferes with a satisfactory fit shall be altered or removed. 10. If a test subject exhibits difficulty in breathing during the tests, she or he shall be referred to a physician or other licensed health care professional, as appropriate, to determine whether the test subject can wear a respirator while performing her or his duties. 11. If the employee finds the fit of the respirator unacceptable, the test subject shall be given the opportunity to select a different respirator and to be retested. 12. Exercise regimen. Prior to the commencement of the fit test, the test subject shall be given a description of the fit test and the test subject's responsibilities during the test procedure. The description of the process shall include a description of the test exercises that the subject will be performing. The respirator to be tested shall be worn for at least 5 minutes before the start of the fit test.

70 13. The fit test shall be performed while the test subject is wearing any applicable safety equipment that may be worn during actual respirator use which could interfere with respirator fit. 70

71 71 APPENDIX D North Adapter Installation

72 72 NORTH NORTH MODEL QUANTITATIVE FIT-TESTING ADAPTER NOTE This adapter, when used alone allows for quantitative fit-testing all dual cartridge facepieces used with North 5500, 7600, 7700, and 7800 Series respirators. To perform quantitative fit-testing of facepieces used with North continuous-flow and pressuredemand airline respirators, or a facepiece used with North self-contained breathing apparatus in negative pressure mode, it is necessary to use Facepiece Converter. Please contact a North customer service representative to determine the appropriate Facepiece Converter needed for your facepiece. INSTRUCTIONS 1) Remove suction cup from 2) Insert test probe (with terminal) Adapter terminal. through cartridge connector on facepiece and screw Adapter firmly onto cartridge connector.

73 73 3a) Reconnect suction cup to terminal 3b) Press suction cup on to inside of the half-mask respirator facepiece. 3c) Make sure that the gasket is in place on the male threaded portion of the Adapter. 3d) Screw onto the Adapter, and onto the other cartridge connector, respectively, North cartridges appropriate for use against the challenge agent specified in the quantitative fit-test protocol to be used. 4) Attach a flexible fit-test monitor tube to the barbed fitting on the Adapter. 5) Perform a fit check following fit check instructions specified in the manual for the particular facepiece model you are working with. Warning Use this adapter only for fit-testing North facepieces. Do not use a respirator equipped with this adapter or any other fit-testing component for protection against any hazardous atmosphere. Contaminated air will enter through the barbed fitting or the Adapter resulting in serious injury or death. (Adapted NORTH, 1995).