Dec. 7, 2007: Source – Science Daily

London Traffic Congestion

A new study published in the New England Journal of Medicine says the lung function of people with asthma is harmed by the effects of diesel traffic pollution. A British medical research team is the first to study the health effects of diesel exhaust in a real-life setting. Their research site was Oxford Street in London, one of the busiest urban shopping districts in that country.

"The results of our study show for the first time that roadside exposure to diesel traffic can be harmful for asthmatics. 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 Dr. Paul Cullinan, of the Royal Brompton Hospital and team leader of the study.

Modern, cleaner-burning diesel powerplants produce far fewer emissions than previous generations of diesel vehicles. However, these so-called “clean diesels” have only recently emerged on the market. Diesel engines manufactured before advances in the technology—and which generally stay in use longer than gasoline engines—will continue to cause health-related problems for many years.

Researchers looked at what effect a two-hour walk in two different London settings might have on 60 volunteers, all asthmatics to some degree. First, volunteers walked on the heavily-congested Oxford Street, where only buses and taxis are allowed, all of them diesel-powered. The second walk occurred in a traffic-free section called Hyde Park.

The researchers observed a much greater reduction in lung function when the participants were walking down Oxford Street, compared to Hyde Park. On Oxford Street, volunteers experienced increased asthma symptoms, reduced lung capacity, and inflammation in the lungs. In Hyde Park, just a few miles away, they experienced some of the same problems, but to a far lesser degree.

Air quality tests showed three times as many ultra fine particulates, as well as three times the nitrogen dioxide level in the air at Oxford Street than in the air samples taken in Hyde Park. From this data, the study reports a direct link between the severity of lung problems with the amount of pollution spewed by diesel vehicles.

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