Are infants who swim more likely to get asthma?

infant swimmingby Devika Rao, MD, Pulmonary Fellow

For a pediatric pulmonologist, the winter brings numerous questions from parents and other physicians regarding the management of recurring breathing problems in infants. Some of these infants have colds and some have chronic wheezing.

Some are hospitalized with bronchiolitis – an inflammation of the small airways of the lung. Bronchiolitis is typically caused by viruses, most commonly the respiratory syncytial virus (RSV) and infection rates peak from December to March. Symptoms range from just a cold with a runny nose, to wheezing or even severe difficulty breathing requiring hospitalization.  Some of the many known risk factors that predispose children to bronchiolitis include daycare attendance, tobacco smoke exposure and prematurity.

A recent study suggests that exposure to pool water in infancy may increase the risk of bronchiolitis. The results of this study showed that 36 percent of children who were exposed to pools before the age of two got bronchiolitis compared with 24 percent of children with bronchiolitis who did not swim during infancy.

The study’s results show that infants who swam for more than 20 hours had an increased risk for bronchiolitis compared to infants who either did not swim or who swam for a fewer number of hours.  The study suggests that exposure to chlorine byproducts in the pool water can cause inflammation of lung airways making infants more susceptible to infection.

I’m hesitant to apply the results of this study to all infants and children for several reasons.

  • The information collected in this study was based on surveys asking parents to remember their children’s medical history from several years prior to when the questionnaire was distributed which can result in inaccurate information.
  • A higher percentage of infants in the study who swam had a family history of asthma. This can predispose an infant to wheeze with viral illnesses, increasing the chances that a diagnosis of bronchiolitis may be made.
  • It’s possible the increased amount of bronchiolitis is because of increased exposure to other sick children at pools rather than breathing in irritants – a variable the study did not consider.

child swimmingParents should be aware that while the relationship between pool exposure and respiratory health has not been well established, it is possible that the by-products of chlorination may be harmful to lung airways. When combined with organic contaminants such as urine or skin particles, chlorine can form potentially harmful byproducts known as chloramines, which cause the typical “chlorine” smell of pools and can lead to eye and skin irritation. Studies done in elite athlete swimmers have actually found higher levels of inflammation in their lungs, presumably due to the effect of chlorine byproducts.

However, rather than completely restrict water-based activities for infants, parents should be aware of the potentially irritating nature of chlorine, and more importantly, provide constant supervision of their children around pools.

Drownings are a leading cause of unintentional death in children. The American Academy of Pediatrics recommends delaying swimming lessons until after the age of four, when children are neurodevelopmentally fit to learn to swim.

Parents should also be aware that swimming is a wonderful form of exercise for asthmatic children, given the relatively humid environment that can prevent airway constriction seen with other forms of exercise. Parents can also ask whether the pools they allow their children to attend are within the recommended concentration of chlorine in the US of 1-3 mg/L.

Water-based recreation for infants and children can and should be a safe, enjoyable experience for both the child and parent.