The finding came from a new study conducted in 10 European cities which found that traffic pollution is responsible for 14% of chronic childhood asthmas, showing a similar effect that passive smoking has on asthma.
The World Health Organization (WHO) says between about 4% and 18% of asthma cases in children are associated with passive smoking.
The new study was published in the European Respiratory Journal and is significant because earlier this year, the European Commission declared 2013 the "Year of Air", which emphasizes how critical clean air is for adults and children and centers on actions to improve the quality of air throughout the EU.
A study from 2010 indicated that exposure to air pollution is linked to the decreased function of a gene that appears to increase the severity of asthma in kids, while another study showed thatchildren aged 4 and under are most at risk for asthma attacks from traffic-related air pollution.
Prior to this novel research, traffic pollution was thought to only trigger symptoms of asthma, and burden estimations did not explain chronic asthma that resulted from the certain range of toxicants that are located near frequently used roads where several Europeans reside.
In order to evaluate the effect of near-road traffic pollution, the team of experts used a method called population-attributable fractions. This measures the proportional decrease in illness or death that would occur if exposure to a risk factor were reduced to a lower level.
Data were gathered and analyzed from previous epidemiological reports which indicated that kids exposed to higher levels of near-road traffic-related pollution also had increased rates of asthma, even when considering a range of other related factors, including socioeconomic factors or passive smoking.
The experts wanted to take these results further and find out how many cases of asthma could be prevented if exposure was eliminated.
Results showed that across the 10 European cities, 14% of asthma cases could be credited to near-road traffic pollution.
The scientists pointed out that the health of the overall population in various cities were taken into account.
A previous U.S. study showed that at least 8% of the more than 300,000 cases of childhood asthma in Los Angeles County can be attributed to traffic-related pollution at homes within 75 meters (nearly 250 feet) of a busy road.
Lead author, Dr Laura Perez at the Swiss Tropical and Public Health Institute, concluded:
"Air pollution has previously been seen to trigger symptoms but this is the first time we have estimated the percentage of cases that might not have occurred if Europeans had not been exposed to roadtraffic pollution.
In light of all the existing epidemiological studies showing that road-traffic contributes to the onset of the disease in children, we must consider these results to improve policy making and urban planning."
Written by Sarah Glynn