Determinants of exposure to volatile organic compounds in four Oklahoma cities.
Phillips-ML; Esmen-NA; Hall-TA; Lynch-RL
J Expo Anal Environ Epidemiol 2005 Jan; 15(1):35-46
To begin to develop generalized models for estimating personal exposure to ambient air pollutants within diverse populations, the design of the Oklahoma Urban Air Toxics Study incorporated eight dichotomous macroenvironmental and household factors that were hypothesized to be potential determinants of exposure. Personal, indoor, and outdoor samples of volatile organic compounds (VOCs) were collected over 24-h monitoring periods in 42 households, together with activity diaries and data on the participants' residences. The distributions of the VOC concentrations were moderately to highly left-censored, and were mostly bimodal. The ATSDR minimal risk level (MRL) was exceeded in a small number of the samples. Personal and indoor concentrations tended to be higher than outdoor concentrations, indicating that indoor exposures were dominated by indoor sources. However, indoor concentrations were not correlated with the permeability of the residence, suggesting that the observed indoor concentrations reflected mostly localized, short-term emissions. The influence of the eight dichotomous factors and of the presence of an attached garage was evaluated using the Wilcoxon rank-sum test and by comparison of "excursion fractions", that is, the fractions of each distributions exceeding 10% of the MRL. Dry weather and absence of children in the household were found to be associated with higher exposures in personal or indoor exposures. Given the small sample size, it is possible that these factors were confounded with unidentified household characteristics or activities that were the true determinants of exposure.
Air-contamination; Air-quality; Analytical-methods; Environmental-exposure; Environmental-health; Exposure-levels; Exposure-limits; Humans; Men; Women; Organic-chemicals; Risk-analysis; Age-groups; Seasonal-factors;
Author Keywords: determinants of exposure; urban air toxics; volatile organic compounds; indoor air quality; censored data; natural ventilation
Margaret L. Phillips, Department of Occupational and Environmental Health, College of Public Health, University of Oklahoma Health Sciences Center, 801 Northeast 13th street, Oklahoma City, OK 73104
Journal of Exposure Analysis and Environmental Epidemiology
University of Illinois-Chicago