Association of school absence with air pollution in areas around arterial roads.

Association of school absence with air pollution from suspended particulate matter (SPM) and nitrogen dioxide was analyzed in areas around arterial roads for five years, from 1993 to 1997. The prevalence of absence was calculated using the data for school absence in two schools around arterial roads, one of which is near a crossing (Sch.A), and the other is adjacent to an arterial road (Sch.B). Although the results from annual correlation analyses did not indicate common findings for five years or in the two schools, the prevalence of absence correlated positively with SPM, nitrogen dioxide, or relative humidity, and negatively with atmospheric temperature. As the results from multiple regression analyses, atmospheric temperature in Sch.A was adopted as the optimum explanatory variable, whereas SPM and relative humidity were considered in Sch.B. Odds ratios for the prevalence of absence to SPM were elevated and were significant in Sch.B, when using a quintile method. The other odds ratios for the air pollutants were not significant, but exceeded 1. When the data were classified by day of the week, significant associations of the prevalence of absence were observed with atmospheric temperature in Sch.A and with SPM in Sch.B. The slope of the regressive equations by day of the week became steeper with the day in Sch.B. SPM was weakly associated with the prevalence of absence in Sch.A and was closely associated in Sch.B according to the optimum variables selected from the multiple regression analyses by day of the week.