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:
Consider installing a chlorine salt system. This type of system generates chlorine by electrolysis of dissolved salt, instead of manually dosing the pool with chlorinating chemicals. Chlorine generators avoid the need for constant handling of chemicals. Salt systems have a very high start-up cost, but in the long run, they’re cheaper than manually adding chlorine, and make it easier to maintain levels. Salt water is also less drying to the skin, and can even be beneficial to certain kinds of dry or irritated skin. A salt system will introduce a slight smell and taste of salt, but not nearly as strong as seawater. Also, check your chlorine levels frequently, ‘free’ as well as total. Make sure your pool has more than the recommended amount of ventilation, filtration and pumps, and is cleaned regularly.
If you swim in other people’s pools:
Where possible, avoid indoor pools which use standard chlorination altogether. Many indoor pools are switching to a salt system, which seems to reduce the amount of nitrogen trichloride in the air. Make sure your indoor pool is well-ventilated, frequently cleaned and refilled, has sufficient filters and pumps for the pool volume, and that hygiene rules are enforced. Be aware that some states require certain levels of chlorine use in public swimming pools for public health reasons. Ask your pool attendant or facility management about chlorine levels, air quality, and pool management. If you notice the smell of ‘chlorine’, complain to the management – and consider switching pools if the problem is frequent. Spend as little time in an indoor pool or hot tub area as possible; don’t socialize or hang around the area other than to swim, and ask children to socialize and play in a more ventilated area. If you have asthma, make sure you always have a rescue inhaler with you in the pool area.
Do your part – shower with soap before swimming, and encourage others to do so. Water alone won’t take off sweat and body oils, let alone products you’ve applied. Some pool owners speculate that enforcing shower rules would reduce the amount of irritant by-product chemicals by 50%! Of course, athletic swimmers will sweat no matter what. A good pool manager will take note of when swim meets, practices, and peak use times are, and check levels accordingly. Swimmers with asthma may wish to ask their pool personnel about these as well, and avoid swimming just after the local Olympic hopefuls.
More good news: it’s believed that the effects of exposure to nitrogen trichloride are completely reversible in the long run. Many regular swimmers who switched pools or quit swimming altogether noticed a marked decrease in their asthma symptoms, and in the study mentioned above, adult employees in pool area found their asthma-like symptoms diminished or disappeared when they switched to jobs away from indoor pools.
If you or a child develop breathing difficulties during or after a swim, or notice that asthma worsens as a result of regular swimming practice, see your doctor about asthma treatment and prevention. Swimming is very good exercise for all sorts of people – it’s low-impact, involves the whole body, and is easily ‘scaled’ up or down to meet your needs. So don’t give up swimming if you’re worried about asthma! But do look for pools with clean air and water to help keep your lungs in the best of health.