http://www.cdc.gov/healthyswimming/irritants.htm
April 25, 2007

Irritants (Chloramines) and Indoor Pool Air Quality

Pool operators may be getting complaints from swimmers and pool staff about stinging eyes, nasal irritation, or difficulty breathing after being in the water or breathing the air at swimming pools, particularly indoor pools. New research indicates that these symptoms may be an indication of poor water and indoor air quality at the pool caused by a build-up of irritants, known as chloramines, in the water and air.

Irritants in the air at swimming pools are usually the combined chlorine by-products of disinfection. These by-products are the result of chlorine binding with the sweat and urine from swimmers using the pool. As the concentration of by-products in the water increases, they move into the surrounding air as well. Breathing air loaded with irritants can cause a variety of symptoms depending on the concentration of irritants in the air and amount of time the air is breathed. The symptoms of irritant exposure in the air can range from mild symptoms such as wheezing, to severe symptoms such as lung disease and, potentially, asthma1-3. It is also known that routine breathing of irritants may increase sensitivity to other types of irritants such as fungi and bacteria.

The buildup of these irritants in the air is partially due to poor air turnover. The poor movement of fresh air over the pool surface, combined with the use of air recycling devices to control heating costs, leads to poor air exchange. Recyclers remove the moisture from the air, but they do not necessarily take in much fresh outside air. This may save money on heating, but the health risks to patrons and staff associated with the excessive use of these devices outweigh the financial benefits2. Without adequate fresh air, the recycled air flowing over the pool becomes saturated with chlorination by-products so that it can no longer absorb or pick up new by-products coming from the pool water. Because recyclers do not remove all of the by-products in the air, they allow the irritants to accumulate and reach unhealthy levels. In addition, if the air is saturated with irritants, new irritants produced in the water will stay in the pool water causing further irritation, such as stinging or red eyes, for swimmers. Fresh air is important; super chlorination can be an effective way to rid the pool water of these by-products but will not work if the air is saturated with irritants.

The problem of poor indoor air quality can be fixed through a combination of prevention measures. Improving air movement over the pool and increasing the air turnover rate will reduce irritant levels in the air. One option is to open all of the doors and windows in the pool area or use fans to boost airflow over the pool surface when many swimmers are using the pool. When super chlorinating, do the same. Also, ensure that the air recycling systems are bringing in enough fresh air. Adequate disinfectant levels and constant monitoring of water quality can also help reduce irritant levels by decreasing combined chlorine formation in the water. Combined chlorine levels in the water may be reduced by adding supplementary disinfection systems such as ultraviolet light or ozone. In addition, good hygiene is needed. Getting swimmers to shower before getting in the pool and promoting regular bathroom use to reduce the amount of urine in the pool will decrease the formation of irritants.

For the health of pool staff and patrons, remember that all indoor pools need adequate fresh air exchange and all pools need good water quality. This will help make all pools a healthier and more enjoyable place to play and work.

For more information on the topic:
1. Bowen A, Kile J, Austin C, Otto C, Blount B, Kazerouni N, Wong H-N, Mainzer H, Mott J, Beach MJ, Fry AM. Outbreaks of short-incubation illness following exposure to indoor swimming pools. Environ Health Perspect, 2007; 115: 267-271.
2. Emanuel BP. The Relationship Between Pool Water Quality and Ventilation. Environmental Health, 1998; 2: 17-20.
3. Ratner J, Griffiths T. Exercise-Induced Asthma and Indoor Swimming Pools. Parks and Recreation. 1995; 7: 46-51.