Personal exposures to particulate matter among children with asthma in Detroit, Michigan

Abstract

From 2000 to 2001, eight two-week seasonal intensive measurement campaigns were conducted in Detroit which included daily ambient and indoor measurements of PM10 at two elementary schools. Concurrent measurements of PM10 inside the homes of 20 children, aged 7–11 years, with asthma as well as personal PM10 measurements for the same 20 children were performed. Sampling was changed from 24-h measurements to 8-hs in the classroom and 16-hs in the home in 2001 to more closely match the times spent by the children in these microenvironments. The mean personal PM10 concentrations were 57.1±41.0 μg m−3and 47.6±34.6 μg m−3 for children residing in homes with and without smokers, respectively. The mean personal PM10 exposures exceeded the mean classroom and ambient PM10 concentrations. The personal exposures of children residing in homes with non-smokers also exceeded the mean home concentration of 33.1±23.4 μg m−3 in 2000 and 16-h concentration of 27.2±22.8 μg m−3 in 2001. Among children residing in homes with smokers, their mean personal concentrations were less than the 24-h (65.1±43.0 μg m−3) and 16-h (81.7±68.9 μg m−3) concentrations measured in their home for 2000 and 2001. As the children spent an average of 70% of their day at home, their personal PM10 concentrations were significantly correlated with their home environment (Pearson's r=0.38 to 0.70), with the strongest relationships observed in homes with non-smokers. Weak correlations were observed between the personal concentrations and those in the ambient and classroom environments. The correlations between the children's personal exposures and the ambient and classroom concentrations improved when analyzed longitudinally, with the strongest correlations observed in 2001 (median Pearson's r>0.41, overall). The children's exposures, however, remained most strongly correlated with PM10 measured in their homes (Pearson's r>0.50). The mean unexplained contributions to personal PM10—based on measured and modeled personal exposures—were greater among children in homes with non-smokers. The lowest estimate was observed in 2001 among children in homes with smokers, at 0.22±28.29 μg m−3. Overall, the model explained 37% and 45% of the variability in the children's exposures among those in non-smoking and smoking households, respectively, when the measured and modeled personal exposures were compared.