The purpose of this study was to evaluate the relationship between air pollution and asthma exacerbation in children and adults. Pearson analysis was used to establish correlations between air pollutants-sulfur dioxide, nitrogen dioxide, ozone, carbon monoxide, and particles with an aerodynamic diameter of 10 microm or less (PM(10))--and ED visits for asthma in 2004. Among children, there were significant positive correlations between nitrogen dioxide (r = 0.72), carbon monoxide (r = 0.65), and PM(10) (r = 0.63) and ED visits for asthma. Among adults, only weakly positive, non significant correlations between all air pollution measures and ED visits for asthma were found. This study suggests that air pollution plays a role in acute exacerbation of asthma in children but not in adults.