Air pollution increases asthma risk in babies

Toronto: Babies born to mothers exposed to air pollution from traffic sources during pregnancy have an increased risk of developing asthma before the age of five, finds a new study.

Exposure to air pollution from traffic sources during pregnancy increases the risk of developing asthma during the first five years of life, even in urban areas with relatively low levels of pollution, the findings revealed. 

Also, children whose mothers lived close to highways during pregnancy had a 25 percent increased relative risk of developing asthma, the study said.

"Our study results highlight the importance of exposure to pollution while babies are still in the womb. Air pollution from traffic sources increased the risk of developing asthma during early years before children reach school age, even in an urban area with relatively low levels of air pollution,” said Hind Sbihi, from the University of British Columbia in Vancouver, Canada. 

In addition, children born with a low birth weight were more susceptible to the respiratory effects of air pollution, the study showed. 

The risk increased with an increase in levels of nitrogen dioxide and carbon monoxide: two markers of traffic-related air pollution, the researchers said. 

The study, published in the European Respiratory Journal, looks at the role of variation in air pollution in urban areas and the development of asthma, the researchers said.

Over 65,000 Canadian children were included in the study and followed up from birth until the age of 10 years. 

The researchers monitored physician-diagnosed asthma cases among this group and also assessed exposure of mothers to air pollutants during pregnancy. Each mother's postcode was used and exposure level was determined using measures that focused mainly on traffic-related pollutants, including black carbon, fine particulate matter, nitrogen oxide and nitric oxide.