Effect of a diesel engine ban on asthma-related morbidity in Beirut

Abstract

Diesel engine exhaust emissions are a mixture of gases, vapors, liquid aerosols and particulate matter that are known to increase cardiorespiratory morbidity.On July 1, 2002, a ban was imposed on the use of diesel-operated vehicles on the Lebanese territory as a public health measure. The aim of this study is to determine the effect of this ban on the air concentration of particulate matter and on asthma-related morbidity in the Beirut area.Methods: Air sampling was done at multiple large intersections of Beirut before and after the ban using a portable high-volume air sampler equipped with glass fiber filters that capture particles of diameter greater than 0.01 microns. Each sample was collected over a period of 30 minutes. The filter was then weighed for particulate matter determination.The records of all visits to the Emergency Room (ER) of the American University of Beirut Medical Center, a major tertiary care center in Beirut, Lebanon were reviewed over a two-year period. The first year (July 1, 2001 to June 30, 2002 , period 1) preceded the ban while the second year (July 1, 2002 to June 30, 2003, period 2) followed it immediately. All patients 0-15 years of age presenting with acute asthma were identified. Results: The average concentration of particulate matter was 181.3 µg/m3 and 97.1 µg/m3 before and after the ban respectively.The total numbers of ER visits for pediatric patients were 6453 and 6865 in period 1 and period 2 respectively. Of those, 313 were due to asthma in period 1 and 223 in period 2. The number of asthma-related visits was significantly reduced during period 2. When we looked at the monthly distribution of visits, asthma-related visits were significantly reduced during October, November and December of period 2 compared to the same months of period 1, while it was significantly increased during the month of June. Discussion: This study shows that a ban on diesel engine resulted in a decrease in the air concentration of particulate matter and was associated with a reduction in the number of emergency room visits for acute asthma. This reduction was most marked during the season of viral respiratory infections. We postulate that a reduction in the concentration of air pollutants was protective against viral-induced asthma exacerbations.<br/