NEW YORK: The closer people live to a main road, the more likely they are to suffer from respiratory symptoms such as breathlessness and wheezing, a new study from Switzerland shows.

"These findings from a general population provide strong confirmation that living near busy streets leads to adverse respiratory health effects," Lucy Bayer-Oglesby, of the University of Basel, and colleagues write in the American Journal of Epidemiology.

While outdoor air pollution especially tiny particles that can be breathed deep into the lungs — is known to be hazardous to people's health, to date no researchers have looked at how proximity to main roads affects respiratory symptoms in a general population, Bayer-Oglesby and her team note.

To investigate, they looked at data from a two-part study of air pollution and lung disease. It involved 9,651 randomly selected men and women aged 18 to 60 who enrolled in the study in 1991, 8,047 of whom re-enrolled for the second phase of the study in 2002.