Long-term Personal Exposure to Traffic-related Air Pollution Among School Children: A Validation Study

Abstract

SS6-11 Introduction: Several recent studies suggest an association between long-term exposure to traffic-related air pollution and health. Most studies use indicators of exposure such as traffic density on the street of residence or outdoor air pollution as a measure of exposure. Very little information is available about the validity of these measures as an estimate of long-term personal exposure to traffic-related air pollution. In this study, we therefore assessed outdoor and personal exposure to traffic-related air pollution in locations with different degree of traffic intensity. Methods: Personal exposure to traffic-related air pollution was monitored in children (10–12 years) attending 4 different schools with varying proximity to traffic in Utrecht. Subjects wore personal PM2.5 monitors for 4 48-hour periods spaced over a 9-month period. Personal monitors are carried in small backpacks and, simultaneously, Ogawa passive samplers are attached as a badge to the children's clothing to provide personal NOx measurements. In addition to PM2.5 mass, absorption of PM2.5 filters is measured as a marker for diesel soot (EC). Results: Fifty-four children enrolled into the study. Of these, 15 attend a school near a highway (97,800 vehicles/24 hours), 11 attend a school near a busy local road (45,200 vehicles/24 hours), and 28 attend an urban background school. Due to pump failure and sickness of some participants, 34 measurements were lost, resulting in 182 complete personal measurements. Personal and outdoor traffic-related long-term exposures were higher in schools near a busy road. Children attending the school with the highest traffic intensities were also exposed to the highest personal concentrations. Personal exposure to “soot,” PM2.5, NO, NOx, and NO2 was, respectively, 30%, 12%, 52%, 31%, and 7%, higher for children attending schools near busy roads compared with children attending schools at an urban background location. Results of the study show that personal exposure to traffic-related air pollution was significantly higher for children attending schools near busy roads.