Childrenʼs Exposure to Diesel Exhaust at a Rural Elementary School

Abstract

SAB5-O-04 Diesel exhaust has been associated with health effects in humans, including respiratory illness and cancer. Children are of particular concern regarding diesel exposure from schools buses because their lungs are still developing and they can be more susceptible to health effects than adults. In this study, a direct exposure assessment was conducted at the elementary school in Potsdam, NY in late October 2005 for 5 days and early February 2006 for 4 days. Sampling was performed for 2 hours in the morning and 2 hours in the afternoon corresponding with the school bus dropoff and pickup times. Matched indoor/outdoor semi-continuous instruments were used to measure ultrafine particle (UFP) counts, particle-bound PAHs, and particle size distribution. One indoor and several outdoor integrated filter samplers collected PM2.5 mass on both quartz and Teflon filters. The filter samples were analyzed for mass and organic and elemental carbon (OC/EC). The highest PM2.5 concentrations were found indoors and the outdoor concentrations in the bus pickup and dropoff area were found to be slightly higher than those from the upwind site. All outdoor PM2.5 concentrations were below 12 μg/m3. The elemental carbon measurements were found to be below the detection limit during the fall field intensive, which is likely due to the fact that the buses shut off immediately upon arrival at the school, reducing the source strength, and the sampling period was short. The sampling period was increased from 4 hours to 8 hours for the winter field intensive. Time-series data from the semi-continuous instruments showed clear increases in UFP number concentration to more than 100,000 particles/cm3 during the times that the buses arrived and departed from the school compared with less than 10,000 particles/cm3 before the buses arrived. A strong correlation between the indoor air and the outdoor particle concentrations was found, and the penetration of the outdoor particles indoors was found to be almost 100%. The results of this study illustrate that the bus pickup and dropoff next to the elementary school results in a short-term, high concentration exposures to UFP both outside and inside the school.