Children aged four and under are most at risk for asthma attacks from traffic-related air pollution, according to a study published in the Medical Journal of Australia.

Gavin Pereira, epidemiologist at the University of Western Australia and CRC for Asthma and Airways, and co-authors conducted a study to determine whether changes in background ozone, nitrogen dioxide, carbon monoxide, and particulates increase the risk of hospital emergency department presentations for asthma among children.

The authors conducted a time-stratified case-crossover study of 603 children and young adults aged 0-19 years, who were exposed to background air pollution and presented to emergency departments with asthma from 2002 to 2006.

Mr Pereira said that children under 4 years of age with previous day exposure to the trafficrelated pollutants, nitrogen dioxide and carbon monoxide, showed the most significant risk of presentation with asthma at an emergency department.

"The odds of an emergency department visit among the youngest age group increased by 70 per cent for an interquartile increase in the previous day's traffic-related air pollution.

"These results were surprising because they were observed for a period in which the national air quality standards were met, indicating that the effect may be due the mixture of toxicants in vehicle emissions rather than the specific pollutants that were measured." Mr Pereira said.

"Further research is required in order to better understand the adverse health effects of this toxic mixture, particularly because it is our very young children who seem to be highly vulnerable."

The Medical Journal of Australia is a publication of the Australian Medical Association.

Source: Medical Journal of Australia