Diesel exhaust fumes affect asthmatics

LONDON, Dec. 6 (UPI) -- A study of 60 people with asthma in Britain found they experienced increased asthmatic symptoms after being exposed to diesel exhaust.

The study subject, all volunteers with mild and moderate asthma, were asked to walk along the western end of a busy London street, where only diesel-powered taxis and buses are permitted.

The researchers from Imperial College London, the New Jersey School of Public Health and other institutions found both during and after a two-hour walk the volunteers experienced increased asthmatic symptoms, reduced lung capacity and inflammation in the lungs.

Fan Chung of Imperial College London said it took a few hours for these symptoms to abate to normal levels. The researchers confirmed the results by having the same people take a two-hour walk in the traffic-free, western part of London's Hyde Park. At this location, the volunteers experienced some of the same problems but to a far lesser degree.

Diesel engines emit lower concentrations of carbon monoxide and carbon dioxide than gasoline engines, but they can generate more than 100 times more particles per distance traveled -- diesel particles are "ultra fine" and can interfere with the respiratory system, the researchers said.

The findings are published in the New England Journal of Medicine.