A retrospective cross-sectional study of traffic-related air pollution and asthma prevalence among young adults in Israel

Abstract

Background: Air pollution from mobile sources has been associated with increasing asthma prevalence. We conducted a retrospective cross-sectional study to evaluate the possible association and its extent between asthma prevalence in young adults and exposure to nitrogen oxides, which are established markers of traffic-related air pollution. Methods: The population studied included 36,874 young Jewish males that underwent a health examination as part of their recruitment into the Israel Defense Forces and that lived in one of 20 cities with one air monitoring station measuring NO, NOx and NO2 levels. The pollutant variables used included half-hourly measurements of NO, NO2, andNOx, available from 1997 through 2008. Results: We found that physician-diagnosed asthma prevalence occurred in 6.5% of the subjects, 3.4% were diagnosed with active asthma and 3.1% were diagnosed with non-active asthma. Generally, the mean exposure levels for all nitrogen oxides among asthmatics were significantly higher than in non-asthmatics population (p<0.001). The results also indicate that different sociodemographic factors were associated with asthma prevalence. Conclusions: We found consistent and significant positive association between asthma prevalence and NOx levels, even when NOx levels were lower than the recommended exposures by environmental protection agencies. Among the active asthma group, odd ratios were considerably higher for NO2 and NOx than among the non-active asthma group, especially at the highest quintile of exposure.