Swimming Pool Air May Be Hazardous

UTRECHT, The Netherlands, March 30 -- Lifeguards, swimming instructors, and other pool rats are likely to wind up with respiratory symptoms, according to researchers here.

The culprit is probably chlorine in the pool water, which reacts with organic substances, such as sweat or saliva, to form chloramines -- substances that are thought to irritate the respiratory tract, found Jos Jacobs, Ph.D., of the University of Utrecht.

The most volatile of the chloramines is trichloramine, which easily migrates from the water to the air above and has been associated with upper respiratory symptoms, Dr. Jacobs and colleagues reported in the April issue of the European Respiratory Journal.

Dr. Jacobs noted that the risk was probably limited to people who spend a lot of time poolside, breathing the air, rather than a short time in the pool swimming.

"Our results concern poolside staff and cannot a priori be extrapolated to visitors," Dr. Jacobs said.

"Swimmers spend most of their time in the water, while staffers are usually beside the pool," Dr. Jacobs said. "And swimming instructors and attendants spend many more hours per week in that environment (than do swimmers)."

The researchers measured trichloramine levels in 38 indoor swimming pools in Holland and analyzed questionnaires about health and lifestyle from 624 pool workers with various levels of exposure to the air in the pools.

The average and highest chloramine concentrations were 0.56 and 1.34 milligrams per cubic meter, respectively, with levels increasing as the number of pool users rose. An additional 50 swimmers meant an increase of 0.40 milligrams per cubic meter of trichloramine in the pool air.

For the analysis of worker symptoms, management, reception, and catering employees formed the reference groups, Dr. Jacobs and colleagues said, because they would have least exposure to the air in pool area.

Compared with the reference group, swimming instructors reported significantly more upper airway symptoms. Specifically, they were more likely to have:

• sinusitis (with an odds ratio of 2.4 and a 95% confidence interval from 1.2 to 4.9).
• chronic cold (with an odds ratio of 3.4 and a 95% confidence interval from 1.2 to 10.1).
• sore throat (with an odds ratio of 2.4 and a 95% confidence interval from 1.2 to 4.5).

Workers who combined the jobs of pool attendant and instructor also had similar increases in upper respiratory symptoms and also reported symptoms associated with rhinitis, such as a congested or runny nose, sneezing, and itchy and watery eyes (with odds ratios ranging from range 2.2 to 3.7).

Compared with the general Dutch population, workers with high exposure to chloramines had significantly more symptoms, Dr. Jacobs and colleagues said, although the pool reference group was equivalent.

For example, they were:

• twice as likely to report breathing problems. (The odds ratio was 2.2, with a 95% confidence interval from 1.8 to 2.8, which was significant at P<0.05.)
• nearly three times as likely to report an asthma attack within the previous year. The odds ratio was 2.6, with a 95% confidence interval from 1.5 to 4.6, which was significant at P<0.05.
• nearly four times as likely to have used asthma medication in the previous year. The odds ratio was 3.6, with a 95% confidence interval from 2.4 to 5.3, which was again significant at P<0.05.

The researchers noted two limitations of the analysis. It relied on memory, which may introduce recall bias, and only about 60% of questionnaires were returned, which may produce a selection bias.