Low level atmospheric sulfur dioxide pollution and childhood asthma

Quarterly analysis (1983-1987) of childhood asthma in Hong Kong from 13,620 hospitalization episodes in relation to levels of pollutants (SO2, NO2, NO, O3, TSP, and RSP) revealed a seasonal pattern of attack rates that correlates inversely with exposure to sulfur dioxide (r = -.52, P less than .05). The same cannot be found with other pollutants. Many factors may contribute to the seasonal variation of asthma attacks. We speculate that prolonged exposure (in terms of months) to low level SO2 is one factor that might induce airway inflammation and bronchial hyperreactivity and predispose to episodes of asthma.