Print full article

Indoor air and water quality

The goal for every professional pool/spa operator is to provide a healthy, odour-free facility for bathers.

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, 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.

Leave a Comment

One comment on “Indoor air and water quality”

  1. Every indoor commercial facility requires Hydroxan. It is the only product that will solve the problem. If the stainless steel railings and the deck equipment are rusted that is a sign of nitrogen trichloride. Water slide stainless steel bolts rusting is nitrogen trichloride reacting with the humidity to form hydrochloric acid (muriatic acid).

Leave a Comment


Your email address will not be published. Required fields are marked *