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ALISON OSINSKI, Ph.D. AQUATIC CONSULTING SERVICES 38331^0..*: ^ SAN DIEGO, CA 92109 (619) 270-3459 (619) 980-5844 Chlorine and Its Effect on Swimmers Alison Osinski, Ph.D. Aquatic Consulting Services 3833 Lament Street, 4C San Diego, CA 92109 June 15, 1992

Why do they put all that chlorine in pool water anyway? Do we really need it? Isn't being exposed to chlorine harmful to our health? We all know too much chlorine in the water causes our hair to turn green, our eyes to be irritated, and the natatorium to have that unpleasant "chlorine smeh"--don't we? It might surprise many swimmers to find out that chlorine is the single most important and most essential product we add to pool water. When transported, stored, handled, and dispensed properly by trained operators, chlorine usage is very safe. Chlorine is added to pool water for two primary reasons, to sanitize and oxidize. Chlorine acts as a bactericide, killing off harmful bacteria and viruses that might cause the spread of disease through the water. Chlorine also oxidizes and removes algae, ammonia and organic products dissolved in the water-the material on which bacteria grow. It accomplishes this by using oxygen to "burn off" the unwanted organic products in the water. There are six forms of chlorine, sold under a myriad of trade or brand names, commonly used to sanitize pool water. There is not a single best chlorine product to use--the best chemical is the one that meets your needs, and which is readily available, affordable, and can be safely handled under the circumstances. [Insert chart here] But regardless of which form of chlorine is used, the same chemical reaction takes place when chlorine is added to water. Only the by-products

Advantages and Disadvantages of the Six Forms of Chlorine Commonly Used in Swimming Pools Elemental Gas Chlorine Sodium Hypochlorite Calcium Hypochlorite Lithium Hypochlorite Sodium Dichloro-strlazinetrione Trichloro-strlazlnetrione Common Name Gas Liquid chlorine or bleach Cal hypo, HTH Lithium Dichlor Trichlor Appearance Produced by: Percentage of Available Chlorine Amount needed to raise chlorine level 1 ppm per 10,000 gallons of pool water ph Nearly invisible greenish Yellowish greenish liquid gas but delivered to pools under pressure in liquid form in 1 50 pound cylinders or one ton steel tanks Separating salt into into its Bubbling gas chlorine elemental products: through a solution of chlorine, hydrogen gas, sodium hydroxide and sodium hydroxide 100% 10-15% or less 1.3 ounces 1.0 or less 1.0-1.5 cups 13 White granular or white pillow shaped tablets Passing chlorine gas over lime 65 or 70% 2.0 ounces 11.8 White powder Bubbling gas chlorine through lithium, sodium and potassium sulfates, then drying 35% 10.5 ounces 10.7 White granular Drying cyanuric acid in the presence of gas chlorine 56 or 62% 2.25 ounces 6.9 Solid white tablets or sticks. Also sold in granular form as an algaecide. Adding sodium carbonate and cyanuric acid to trichlor 90% 1.5 ounces 2.9 Average Cost * 11C -20c per gallon 66c - $1.05 per gallon S1.20 per pound S1.20 - S1.90 per pound S2.15 - S2.35 per pound S1.95-32.25 per pound Stabilized with Cyanuric Acid Injection Equipment Advantages No Chlorinator, scale and booster pump. Injected under vacuum. Inexpensive to purchase. 100% available. No Chemical metering pump (peristaltic, diaphragm, piston) Relatively safe to handle unless splashed or swallowed. Nonflammable. No Made into a liquid solution then injected using a chemical metering pump High percentage of available chlorine. Convenient and easy to use in tablet form. No Predissolve and inject with chemical metering pump Totally soluble-no residue. Safe to handle, non flammable, and doesn't combust. Dust free. Long shelf life. Good product to use for shocking the pool. Yes Dichlor feeder Yes Erosion feeder Neutral ph. no residue or cloudiness. chlorine. Instantly soluble, the water along with the simultaneously added to since cyanuric acid is levels are maintained Stabilized. Cyanuric acid quantity. can be purchased in and use. Long shelf life-- chlorine. Easy to store the water along with the simultaneously added to since cyanuric acid is levels are maintained Stabilized. Cyanuric acid

pisadvantages Expensive to dispense. Dangerous if improperly handled. Toxic-very poisonous to humans, animals, plant life. Unstable. Significantly lowers ph of water. Large quantities are needed so it needs a lot of storage space. Short half life-looses its effectiveness rapidly in heat. Frequent, regular deliveries are required. Unstable. Significantly raises the ph of pool water. Sodium dissolved in the water will eventually give the pool a salty taste. "Special Precautions Must be stored in a Secondary containment is separate, well ventilated required. Goggles or a fun room. An exhaust fan face shield, neoprene capable of making 60 air gloves and a splash guard exchanges per hour must apron should be worn be installed. Individual when handling. tanks must be chained to the wall in an upright position. An USBM approved gas mask with fresh cannister, or self contained breathing apparatus (SCBA) should be worn when exchanging tanks, and must be stored immediately outside the chlorine gas room for use in emergencies. Ammonium hydroxide must be available to test for leaks. Both audio and visual alarms should be installed to warn of chlorine level build up and venting into the surrounding air. Evacuation drills must be practiced on a regular basis. > costs may vary depending on location, availability, and quantity purchased combustible. Partially insoluble-may cloud water if added directly to the pool or in too great a quantity in too short a period of time. Raises ph. Unstable. May contribute to calcification and scale formation. Store in its original container in a cool, dry place. Residue should be disposed of -only the dissolved liquid should be pumped into the pool. Open containers outdoors or in a well ventilated location. Overpacks and chemical clean up equipment must be available to clean up spills. Personal protective gear should be worn when handling. Do not dispose of spilled chemical in the trash or a dumpster-fire may result. Do not re use storage containers-rinse, crush and destroy before disposal. < Flammable and foreign product. or contaminated with a stored, allowed to get wet Unsafe if improperly Extreme Class III oxidizer. High cost. Unstable. Must be predissolved. Raises ph. Cyanuric acid build-up-- Cyanuric acid build-up-- may need to dilute or drain may need to dilute or drain and refill pool on a more and refill pool on a more frequent basis. Cyanuric frequent basis. Cyanuric acid ties up chlorine and acid ties up chlorine and reduces ORP so reduces ORP so maintenance of higher maintenance of higher FAC levels are required by FAC levels are required by most state code. most state code. Do not try to introduce into pool through use of an errosion feeder-lithium dissolves much too radidly. Overpacks and chemical clean up equipment must be available to clean up spills. Personal protective gear should be worn when handling. used in indoor pools. explosion. Should not be in a pressure build up and rapid dissolving will result placed in a trichlor feeder-- Dichlor should never be used in indoor pools. vinyl liners. Should not be etch plaster, and damage will damage pool surface, Tablets sitting in one spot eat them and be poised. pool. Children may try to be placed directly in the Trichlor tabs should never

added during the manufacturing process and left behind in the pool as the chlorine product dissolves, differ. In commercial pools, chlorine must always be added to the pool indirectly and pre dissolved through the recirculation system, via the return lines and inlets. Inlets are evenly spaced throughout the pool in order to provide a uniform circulation and disinfection pattern. It is both an extremely wasteful and potentially dangerous practice to add chlorine by pouring it or placing it directly into a pool. When chlorine is added to water, both hypochlorous acid and a hypochlorite ion form. H20 + C\ = HOCI (Hypochlorous Acid) + OCI- (Hypochlorite ion) Hypochlorous acid (HOCI) is an effective sanitizer and oxidizer. It actively kills bactericide and breaks down organic matter into inactive compounds. It is very ph dependent, being more effective at a ph levels below 7.5. The hypochlorite ion also forms as a by product of the reaction, and causes a drop in ph. It has a tendency to combine with ammonias (NHs) and other nitrogen compounds introduced as waste products by swimmers, to form chloramines. A large percentage of the chlorine added to a pool never has a chance to perform its function. It simply dissipates into the air. Because chlorine is heavier than air, chlorine which dissipates out of indoor pools into natatoriums which are poorly ventilated will settle back over the surface of the pool creating a gas cloud. Lifeguards and long distance or frequent swimmers who spend lengthy periods of time in such environments will probably experience respiratory irritation. The U.S. Environmental Protection Agency has set maximum allowable limits for chlorine presence in the air at 1.0 ppm over an

eight hour exposure period. Ask your pool operator whether air quality is being monitored and whether the facility is complying with ASHRAE and BOCA* standards for ventilation and air quality in indoor pools. Stabilizing chlorine by adding cyanuric acid helps prevent dissipation caused by ultraviolet light in outdoor pools. Keeping pools covered when they're not in use will also significantly reduce chlorine loss due to dissipation. Chlorine when added to the water, is used up in the process of destroying bacteria. This is the chlorine demand-the amount of chlorine needed to react with bacteria and other organic matter already present in the water. The chlorine left over in excess of the chlorine demand is called the chlorine residual, or total available chlorine (TAG). The chlorine residual acts as a type of insurance policy available in the water to react with bacteria and organic matter that we anticipate will be introduced into the pool. The residual chlorine that is free or immediately available to attack incoming bacteria is called the free available chlorine (FAC). Some of the residual chlorine combines with other chemicals or substances such as ammonia in the water and forms combined available chlorines (CAC), which are also called chloramines. Although they are present in the water as part of the residual, they are not freely available. Chloramines will still kill bacteria, but at a rate approximately sixty to one hundred times slower that free available chlorine. High combined chlorine levels are undesirable since they are a major cause of swimmer eye irritation, itchy skin, and mucous membrane irritation. Chloramines are also responsible for the rather unpleasant odor usually attributed to chlorine. * Fresh air should be introduced into the pool area at a rate of 0.5 cfm per square foot of pool and deck area, in compliance with ASHRAE Standard 62-1989 "Ventilation for Acceptable Indoor Air Quality" and BOCA codes (1984 with 1986 supplement).

Chlorine levels in the water, unless excessively high, are not harmful to human health. Minimum free available chlorine levels are often regulated by state health and safety codes. Although levels vary somewhat from state to state, typically minimum FAC levels of 1.0 ppm, or 1.5 ppm in pools stabilized with cyanuric acid, are required. Since chlorine dissipates much more rapidly in warm water pools and spas, minimum FAC levels in the 3.0-5.0 ppm range are recommended. However, swimmers will not be harmed with free chlorine levels maintained at even 10.0 to 15.0 ppm. The problem is not too much chlorine in the water, but rather not enough chlorine to kill bacteria, or chlorine tied up as chloramines resulting in not enough chlorine immediately available to oxidizing organics. Maintaining proper chlorine levels has less to do with the quantity of chlorine added to the water, and more to do the having enough chlorine in the water to complete the oxidation process. To determine whether chlorine levels are adequate, knowledgeable pool operators will install controllers, automate the chemical injection process as much as possible to avoid chlorine level peaks and valleys, and will monitor the oxidation reduction potential, or OR P. Recommended ORP Levels 750 mv (Commercial pools) 650 mv (Residential pools) Two pools sitting side-by-side recording the same FAC levels, may not have the same ORP. ph, cyanuric acid levels and total dissolved solid (TDS) levels all effect the ORP and therefor chlorine's ability to work.

There are alternatives to using chlorine in pools, or products that can be used to lessen the amount of chlorine needed. Each of the chemicals or products has its advantages and disadvantages. Bromine for instance is a much better sanitizer at ph levels commonly found in swimming pools, and a much better choice for sanitizing indoor warm water pools and spas. However, it is a poor oxidizer. Ozone on the other hand is several thousand times more effective at oxidizing organics from the water than is chlorine, but has such a short half life, it won't remain in pool water long enough to provide a measurable residual and sanitize bacteria entering the pool. All of the products or chemicals listed (regardless of some manufacturer's claims that their products are chlorine free) need to be used in combination with either small amounts of chlorine or another sanitizing or oxidizing product, to work as effectively as chlorine alone. Alternatives to Using Chlorine Bromo-chloro-dimethlhydantoin (BCDMH-Bromine) Potassium iodide (Iodine) Ozone (Corona discharge) Ozone (Ultraviolet light) Ozone (German DIN Standard) lonization of metals Chlorine generators (brine or off-line method) Chlorine generators (electrolytic cells or in-line method) Polymeric biguanide (Baquacil) The reason chlorine is so commonly used as a stand alone product in U.S. swimming pools, is that it works well as both a sanitizer and oxidizer. Pool operators are familiar with its use, its cost is reasonable, and it is extremely effective.

By the way-chlorine in pool water does not cause hair to turn green, produce an odor, nor does it cause eye irritation. These are all myths or misunderstandings of water chemistry perpetuated by swimmers. Chlorine is a bleach, it causes hair to lighten or bleach out, but not to turn green. Chlorine does cause the cuticle, the protective outer protein layer on hair shafts to be eaten away, resulting in dry, brittle, damaged hair. The split ends are then easily able to absorb dissolved metals such as iron or copper which should not be, but often are, present in pool water. Metals are introduced in a variety of ways, through source water, dissolving of metal pipes and components in the pool recirculation system, or may be contained in chemicals or products used in maintaining pools such as ionizers, and copper or silver based algaecides. When metals are absorbed by the hair shaft and oxidized by chlorine, color results. Shampoos containing the chelating agent EDTA (ethylenediamene tetracetic acid) will help reduce metallic build up and will remove some oxidized metals from hair. Washing your hair in dissolved aspirin will have the same effect. Chlorine in the water does not cause swimmers' eyes to burn nor does it cause the often referred to "chlorine odor" in pools. This is from maintaining high combined chlorine (chloramine) levels in excess of 0.2 ppm, and not having enough chlorine in the water to oxidize and remove the organic contaminants. It's similar to rotting garbage trying to biodegrade-there's not enough chlorine to complete the oxidation process. To learn more about pool chemicals including chlorine and how they effect swimmers, consider enrolling in a Certified Pool Operator course offered through the National Swimming Pool Foundation, or one of the equivalent courses offered by the National Recreation and Park Association, National Spa & Pool Institute, or the YMCA. For more information on chlorine safety, contact

The Chlorine Institute, at: 2001 L Street NW, Suite 506, Washington, DC 20036, (202) 775-2790.