Air Pollution Raises Infants' Risk of Bronchiolitis
Infants who are exposed to higher levels of air pollution, including vehicle and industrial emissions and wood smoke, are at increased risk for bronchiolitis. The study is unique because it evaluated multiple sources of air pollution and their impact on infants’ health.
Bronchiolitis is a common illness of the respiratory tract that is caused by an infection that impacts the minute airways call bronchioles, that lead to the lungs. When these airways become inflamed, they fill with mucus and make breathing difficult. Because infants and young children have especially small airways, they are more susceptible to bronchiolitis. Disease occurrence usually peaks at about 3 to 6 months of age and is more common in children who have not been breastfed.
The new study, which was published in the November 15 issue of the American Journal of Respiratory and Critical Care Medicine, included analysis of nearly 12,000 diagnoses of infant bronchiolitis between 199 and 2002 in southwestern British Columbia. Pollutants monitored included nitric oxide, nitrogen dioxide, carbon monoxide, sulfur dioxide, and particulate matter from monitoring stations within 10 km of where the infants lived.
The researchers found that bronchiolitis was significantly associated to an increased lifetime exposure to specific pollutants. Specifically, with respect to each of the pollutants, the infants’ risk increased by 8 percent (nitric oxide), 12 percent nitrogen dioxide) 4 percent (sulfur dioxide), and 13 percent (carbon dioxide). A 6 percent increased risk was found among infants who lived with 50 meters of a highway, and an 8 percent increased risk was associated with wood smoke exposure.
Although the increased risk of bronchiolitis seen in this study was not severe, the authors note that it is important to pay attention to the impact of air pollution because it is so ubiquitous, that bronchiolitis is the main reason children are hospitalized during the first year of life, and that reducing air pollution may be one way to decrease the occurrence of the disease.
Bronchiolitis is often mild, yet some infants are at risk for more severe disease that requires hospitalization. Factors that increase the risk of severe bronchiolitis include prematurity, presence of chronic heart or lung disease, and a weakened immune system associated with illness or medication use. Children who have had bronchiolitis may be more likely to develop asthma later in life as well.
The results of this study may highlight the need for physicians to educate parents about the impact air pollution can have on their infants and how they can avoid it. It also strengthens the relationship between ambient air pollution and the development of respiratory disease among infants and children and why places where children spend a lot of time (e.g., school, playgrounds) should not be near highways and facilities that pollute the air.
American Thoracic Society