Characterization of fine particulate matter in Ohio: Indoor, outdoor, and personal exposures

Abstract

Ambient, indoor, and personal PM 2.5 concentrations were assessed based on an exhaustive study of PM 2.5 performed in Ohio from 1999 to 2000. Locations in Columbus, one in an urban corridor and the other in a suburban area were involved. A third rural location in Athens, Ohio, was also established. At all three locations, elementary schools were utilized to determine outdoor, indoor, and personal PM 2.5 concentrations for fourth and fifth grade students using filter-based measurements. Three groups of 30 students each were used for personal sampling at each school. Continuous ambient PM 2.5 mass concentrations were also measured with tapered element oscillating microbalances (TEOMs). At all three sites, personal and indoor PM 2.5 concentrations exceeded outdoor levels. This trend is consistent on all week days and most evident in the spring as compared to fall and winter. The ambient PM 2.5 concentrations were similar among the three sites, suggesting the existence of a common regional source influence. At all the three sites, larger variations were found in personal and indoor PM 2.5 than ambient levels. The strongest correlations were found between indoor and personal concentrations, indicating that personal PM 2.5 exposures were significantly affected by indoor PM 2.5 than by ambient PM 2.5. This was further confirmed by the indoor to outdoor (I/O) ratios of PM 2.5 concentrations, which were greater when school was in session than non-school days when the students were absent.