Indoor air and water quality

by Sally Bouorm | August 1, 2010 9:37 am

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By Dennis Ashworth

The facts concerning aquatic facility air and water quality are well researched and have been scientifically documented worldwide. Research shows air quality is completely dependent on pool/spa water quality and bather cleanliness, as air quality problems originate in the water—not in the air.

Ernest R. Blatchley III PhD., PE, BCEE, a civil engineering professor at Purdue University in West Lafayette, Ind., examined the reaction between chlorine and pool/spa water containing bather contaminants, such as urine, sweat and creatinine and the resulting effects on air quality. His research reinforced that chlorine shock treatment[2], super chlorination or simply adding more chlorine only increases the problem when the sanitizer reacts with bather waste. Toxic chlorine byproducts (chloroform) may also be absorbed through the skin, as chloroform has been found in the blood of competitive swimmers.

Swimmers naturally leave behind ‘bather waste’ simply by exercising in a pool or spa. When sweat reacts with hypochlorous acid (HOCl) (free chlorine) byproducts are formed, which can be hazardous to bathers drawing air into their lungs at the surface of the water. For example, in a 400,000-L (100,000-gal) indoor swimming pool with 300 to 500 bathers per day, the volume of bather waste is approximately 300 to 500 L (79 to 132 gal). This includes fecal matter, body lotions, under arm deodorant, skin creams, cosmetics, hair care products, suntan lotions and skin flakes.

According to recent statistics from the Centers for Disease Control and Prevention (CDC), one in five bathers will urinate while in a pool or spa. This is a great concern for bather health, due to the toxic chlorine byproducts that are created. As previously mentioned, simply adding more chlorine is not the solution, as it only creates additional problems—especially for indoor aquatic facilities. With more than 187 toxic byproducts identified to date, higher chlorine concentration in the water will facilitate the production of more toxic byproducts, which in turn reduces air quality.

Laboratory setting yields different results

When methods such as chlorine shock and ‘breakpoint’ chlorination were originally discussed in the 1970s, tests were performed in a lab setting with chlorine and ammonia and not in an actual pool/spa environment. During Blatchley’s study it was discovered that very little ammonia exists in swimming pool water; however, a large amount of chloramines were present. Indoor air quality problems originate from chloramines, which are formed in all pools when chlorine molecules attach to ammonia and other organic byproducts of the human body. Sweat, urine or other types of ammonia are the most common sources of nitrate in pools.

Urea [(NH₂)₂CO], the precursor to nitrogen trichloride (NCl₃), is a solid, colourless and odourless organic compound; however, the ammonia, which it gives off in the presence of water, including water vapour in the air, has a strong odour. Nitrogen trichloride is a strong-smelling liquid, which is most commonly encountered as a byproduct of chemical reactions between ammonia-derivatives and chlorine (e.g. in swimming pools between the sanitizer (chlorine) and urea in urine from bathers).

The formation of nitrogen trichloride can be prevented by using Hydroxan,^® a liquid compound that forms chlorine dioxide (ClO₂) when introduced into chlorinated pool/spa water. Chlorine dioxide is a powerful oxidizing agent, which does not form undesirable chlorine byproducts as a result of oxidation. However, using the procedure known as ‘breakpoint’ conventional shock chlorination is not likely to be effective in controlling urea, as it is slow to react and produces nitrogen trichloride, which is corrosive to the building envelope as well as bathers, according to Blatchley and numerous other scientists throughout the world who haven written practical scientific papers based on tests performed in the swimming pool environment.

pH and air quality

The scientifically supported pool water treatment method regarding pH balance has been devised in almost every existing swimming pool or spa and has been studied by professional pool operators worldwide. Everyone agrees, recreational water must have a pH above 7.2, but lower than 7.4 (when using chlorine as a sanitizer). By keeping the pH within this range, a greater percentage of hypochlorous acid can be produced. Greater chlorine activity provides pool operators better control over water quality, providing flocculation filtration is employed. Chemical flocculating agents cause colloids and other suspended particles in liquids to aggregate, which improves the sedimentation or filterability of small particles.

The concept of operating an aquatic facility with free chlorine levels over 1.2 parts per million (ppm) to overcome poor filtration and mechanical design also creates high combined chlorine issues. The filter is the dirtiest part of the circulation system, as it collects all of the bather waste from the water. As this waste is collected, pressure progressively builds on the filter media (e.g. cartridge, perlite, diatomaceous earth [DE] or sand) and towards the end of the filter cycle, dirt begins to re-contaminate the pool/spa’s plumbing and water. The accumulated bather waste and the continuous addition of more bather waste creates a contamination ‘overload,’ which must be removed—not with chlorine, but with agglomeration. As bather load increases, the facility’s air quality suffers.

Removing bather waste

The goal for every professional pool/spa operator is to provide a healthy, odour-free facility for bathers. A proper water treatment procedure should agglomerate (collect) bather waste and remove the colloids left behind by bathers, as well as remove the microscopic suspended particles, which scatter light (known as the Tyndall effect). Bathers, supply water and the pool shell all contribute to suspended matter in the water, which causes cloudiness. Removal of this matter is critical and preventable by enforcing a bather cleanliness regimen and using an efficient water treatment system, such as the Wapotec System,^® which allows a facility to operate with improved water quality through an effective flocculation/filtration process and improved oxidation. In turn, this also dramatically improves the aquatic facility’s air quality by reducing the amount of bather contaminants, which form chlorine byproducts.

 

Dennis Ashworth is president of SP&S^® Commercial Swimming Pool & Spa Equipment. He joined the aquatics industry in 1963 and has been a National Swimming Pool Foundation (NSPF) certified instructor since 1974. He can be reached via e-mail at swimpool@msn.com[3].

Source URL: https://www.poolspamarketing.com/trade/indoor-air-and-water-quality/

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