Air pollution as a determinant of asthma among schoolchildren in Mohammedia, Morocco.

The objective of the study was to investigate whether air quality in western Morocco is truly a significant risk factor in the development and exacerbation of respiratory diseases and, in particular, asthma. The continuous measurement of the mean concentrations of sulfur dioxide (SO(2)) in the air and the density of Total Suspended Particulates (TSP) for a period of four years was determined. Information on individual characteristics and indoor environments from 1318 children with an average age of 12 years was evaluated by questionnaire, completed by parents (assisted by professional investigators) and symptoms/diseases were medically diagnosed and reported. We have used the Student's t-test, Chi-square tests & odds ratios (ORs) with 95% confidence intervals (CI 95%) for estimates of the risk of asthma. The prevalence of asthma varies in a significant way according to the zone (chi(2) = 14.61, p < 0.05). Respiratory diseases (OR 6.27, 95% confidence interval [CI] 4.09-9.64, p < 0.0001), strongly polluted zone (OR 3.62, 95% CI 1.71-7.81, p < or = 0.0001) and infectious diseases (OR 3.29, 95% CI 1.99-5.47, p < 0.0001) are high risk factors for asthma. Air pollution is a determinant factor but is not the only factor increasing the risk of asthma in children; other factors such as respiratory diseases, infectious diseases, genetic and passive smoking present a high-risk threat.