Are Indoor Swimming Pools Bad for Your Lungs?

Since 2003, several scientific surveys have shown a connection between lung problems and chlorinated indoor swimming pools. Adults who were employed at indoor pools and adults who swam regularly in them showed increased rates of asthma, and children showed even higher rates. Some scientists have speculated that indoor pools may be partly responsible for the rise in childhood asthma in developed countries.

Swimming at indoor pools has often been recommended to asthmatics, as the humid warm air around a pool is often easier to breathe – but not if that air contains lung-damaging toxins. Unfortunately, most pools only measure water quality, not air quality. 

What’s in the air at pools that causes asthma attacks? After all, swimmers aren’t breathing the water! The culprit is usually nitrogen trichloride. Nitrogen trichloride is formed when nitrogen – in the form of sweat, body oils, and other excretions – encounters chlorine, particularly when there is not enough ‘free’ chlorine in a pool. Pool management should always check ‘free’ chlorine levels as well as total levels as only ‘free’ chlorine is available to oxidize pollutants. Nitrogen trichloride has a strong and unpleasant odor, which many people mistakenly think is the odor of chlorine. Nitrogen trichloride irritates the eyes as well as the respiratory tract. It is likely to collect near the surface of the pool, right where swimmers come up for air. Other trichlorides, or tribromines in bromine pools, have been implicated in lung problems to a lesser extent.

So what can you do to protect your lungs – and those of your kids?

If you own your own pool: