Infants exposed to air pollution from traffic may be at risk of reduced lung function, according to a Swedish study that adds to evidence of adverse effects air quality can have on children’s respiratory health.

More than 1,900 Swedish children were followed from birth to age 8 in the study. They were periodically given questionnaires about their health and were given lung function and allergy tests. The researchers also estimated the amount of pollution in the air close to each child’s home, day care, and school.