The lung function of people with asthma is harmed by the effects of diesel traffic air pollution, say researchers in an article published in the New England Journal of Medicine (NEJM), December 6th issue.

Dr. Paul Cullinan, honorary consultant in respiratory medicine, Royal Brompton Hospital, and reader in respiratory epidemiology, Imperial College's National Heart and Lung Institute, both in England, and team's study is the first ever to asses the effects of diesel traffic pollution in a real-life setting.

There are 9 million diesel-driven vehicles in the United Kingdom, according to the Department of Transport - and the numbers are rising.

A diesel engine is known to generate over 100 times more particles than petrol (gasoline) engines - it is widely accepted that these particles pose a health hazard. The authors explain that nearly 90% of traffic-generated particulate in an urban environment is from diesel exhaust fumes.

In this study, the researchers looked at what effect a two-hour walk in two different London settings might have on 60 volunteers - they all suffered from mild to moderate asthma. One walk took place at the western end of Oxford Street, one of the busiest shopping streets in the country - only buses and taxis are allowed on this street, all of them diesel-powered. The second walk occurred in a traffic-free section of Hyde Park, central London.

The researchers observed a much greater reduction in lung function when the participants were walking down Oxford Street, compared to Hyde Park.

"The results of our study show for the first time that roadside exposure to diesel traffic can be harmful for asthmatics. With over five million people in the UK suffering from asthma, it is important that we that we urgently consider practical ways to reduce harmful emissions from diesel vehicles. Our findings may also help city planners to consider how they lay out future road structures to make sure that, where possible, pedestrians' exposure to exhaust fumes is minimized," said Cullinan

"Respiratory Effects of Exposure to Diesel Traffic in Persons with Asthma"
James McCreanor, M.R.C.P., Paul Cullinan, M.D., Mark J. Nieuwenhuijsen, Ph.D., James Stewart-Evans, M.Sc., Eleni Malliarou, M.Sc., Lars Jarup, Ph.D., Robert Harrington, M.S., Magnus Svartengren, M.D., In-Kyu Han, M.P.H., Pamela Ohman-Strickland, Ph.D., Kian Fan Chung, M.D., and Junfeng Zhang, Ph.D.
NEJM - Volume 357:2348-2358 December 6, 2007 Number 23
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