This thesis presents the results of personal, indoor, and outdoor PM2.5 monitored at three elementary schools in central and southeastern Ohio from January 1999 through August 2000. The thesis focuses on the temporal and spatial variations of ambient PM2.5, and the relationships between personal, indoor, and outdoor PM2.5 concentrations.
Ambient PM2.5 depicted an apparent seasonal trend and homogeneous spatial distribution. No clear seasonal or spatial patterns existed for indoor and personal PM2.5 concentrations. However, high variations of personal and indoor concentrations occurred during school days at all three sites. Indoor PM2.5, generated by human activities (i.e. walking, physical motions), was an important determinant of personal PM2.5 exposures. As a result of indoor sources, personal exposures and indoor PM2.5 concentrations tended to be higher than the corresponding outdoor concentrations at all sites. When students were on vacation, indoor and outdoor PM2.5 concentration (I/O) ratios and sulfate (SO42-) I/O ratios decreased.
Indoor PM2.5 also influenced the relationship between personal and outdoor PM2.5 concentrations. Personal PM2.5 concentrations more closely agreed with indoor levels than with outdoor levels. Personal-outdoor correlations for PM2.5 concentrations varied among PM2.5 samples collected in this study. Moderate personal-outdoor correlations occurred at Koebel (R= 0.32, P<0.0001) and Athens (R=0.27, P=0.0001). Only a weak personal-outdoor correlation was found at New Albany (R=0.05, P=0.59). Strong correlation existed between personal and indoor PM2.5 concentrations at all three sites with the R-value ranging from 0.30 to 0.68 (P<0.0001). Moderate indoor-outdoor correlations were experienced at Koebel (R =0.26) and New Albany (R= 0.30). At Athens, indoor PM2.5 weakly correlated with outdoor concentrations (R= 0.13).