Chlorine is capable of reacting with sweat and urine in indoor swimming pools to produce volatile disinfectant by-products

Airborne pollutants are created following the reaction of chlorine with sweat and urine in closed swimming pools, an important step for understanding the ability to reduce the formation of "volatile disinfectant by-products" that cause respiratory irritation

Researchers at the University of Indianapolis were able to determine how airborne pollutants are formed following the reaction of chlorine with sweat and urine in closed swimming pools, an important step in understanding the ability to reduce the formation of "volatile disinfectant by-products" that cause respiratory irritation.
"Some indoor swimming pools have a characteristic odor of chlorine," says environmental engineering professor Ernest Blatcheley. "You may think you smell chlorine, but in fact you smell a mixture of disinfectant by-products. If their concentration is high enough, then irritations begin in the respiratory tract, skin and eyes." The issue became a national issue last summer when the USA Swimming National Championships held in Indianapolis were halted after swimmers complained of difficulty breathing.

In normal swimming water tests, inorganic by-products, or chemical compounds lacking carbon-hydrogen bonds, were discovered. These researchers were the first to discover the presence of "volatile by-products of decontamination", which are carried in the air and are therefore a health hazard. Findings from this study were published last year in the journal "Environmental Science & Technology". Additional findings are expected to appear later this year in the same journal and will also be presented at a global marine health conference to be held in October in Colorado. Two researchers from the School of Civil Engineering at the University of Indianapolis are leading the aforementioned study.

The research is part of a global effort to equalize the marine industry with the same level of scientific rigor as drinking water chemistry research, says Michael Bich, associate director of healthy water at the Centers for Disease Control and Prevention at the National Center for Infectious Diseases from Animals to Humans and Intestinal Diseases. "If you don't know what the exact composition is, you are not able to properly treat the water," he says. "In the above study, various types of compounds were found that can cause possible health hazards." The Center for Disease Control and Prevention has documented cases in which citizens became ill after breathing pollutants in closed swimming pools that were not properly maintained.

"We see this as a very broad problem in the field of public health that we have only just begun to discover, and we must collect more information," says the researcher. Swimming is the most popular hobby among children in the US, and extensive evidence indicates that children may be more sensitive than adults to the irritating effects of these substances, says the researcher. Chlorine is mainly used against the growth of pathogens (microorganisms). "What we are interested in doing now is to test the chemistry of the reactions between chlorine and the substances that humans leave in swimming pools: sweat and urine," says the researcher. "We will also investigate what happens when chlorine reacts with other pollutants including personal care products such as makeup and deodorant." The researchers examined the swimming pool water to find organic compounds formed when chlorine reacts with substances such as creatinine, urea and amino acids, all substances found in human sweat and urine.

The researchers were able to hypothesize about the reactions that occur between chlorine and these substances. "We focused on a number of amino acids that we believe represent those present in urine and sweat and that it is likely that their concentration in swimming pool water will be high," says the researcher. The researchers used an analytical method known as "membrane introduction mass spectrometry" to identify and measure these volatile disinfectants. The accepted method for testing swimming pool water uses a test that causes color changes depending on the composition of the materials in the sample. The test is sometimes not sensitive enough to differentiate between different types of certain chemical compounds.

"Basically, we are interested in matching our measurements with the characteristics of the pool," says the researcher. "To this end, we collect samples from a number of public swimming pools and test them to determine the concentrations of these substances in active swimming pools." "We are also checking what can be done to water to improve its chemistry from the moment these substances were created," says the researcher. "In other words, how can these substances be broken down or prevented from being created in the first place." The new research focuses on the question of what happens to these materials when they react with ultraviolet radiation. "Preliminary findings suggest that in the inorganic materials that contain nitrogen, the radiation causes them to break down into more or less harmless compounds," says the lead researcher. The products of the disinfectants break down into several compounds, among them nitrates and dinitrogen oxygen, also known as "laughing gas". "Currently, we know for sure what happens to about seventy-five percent of the nitrogen, and we believe that we know what happens to the rest of the nitrogen as well, but we must conduct several experiments to confirm this," says the researcher. These findings could shed light on drinking water treated with ultraviolet radiation. "Sometimes ultraviolet radiation and chlorine are used together to treat drinking water," says the researcher.

"The chemistry is similar in these two environments, so our interest in studying these reactions is broader than just swimming pools." "We have a pretty good understanding of the effect of ultraviolet radiation on creatures, but much less of it regarding its effect on these chemicals. Because of this, we are investigating the mechanisms of the reactions and also the extent of their rate of occurrence." In their follow-up study, the researchers plan to interview pool operators to obtain more information, such as the number of people using the facilities and how often the water is disinfected. "It's surprising how little we know about the chemistry of swimming pools," says the researcher. "As a result, the activity of pools is stopped due to reasons that could have been prevented. We are interested in solving this problem so that businesses and municipalities can operate their swimming pools in a way that does not make people sick." "Once we understand the chemistry, our industry will be able to accelerate the development of solutions to improve the quality of the air we breathe, to reduce public sanitation risks and increase knowledge about water reservoirs," concludes the CEO of the National Association of Swimming Pools. We are interested in moving forward in reducing exposure to unnatural substances," he adds and says.