Background: Many young children in the U.S. spend a significant portion of their day in child care facilities where they may be exposed to contaminants linked to adverse health effects. Exposure data on volatile organic compounds (VOCs) and particulate matter (PM) in these settings is scarce. Objective: To guide the design of a larger exposure assessment study in urban child care facilities, we conducted a pilot study in which we characterized indoor concentrations of select VOCs and PM. Methods: We recruited 14 child care facilities in the District of Columbia (Washington, DC) and measured indoor concentrations of seven VOCs (n=35 total samples; 2-5 samples per facility): benzene, carbon tetrachloride, chloroform, ethylbenzene, o-xylene, p-xylene, and toluene in all facilities; and collected real-time PM measurements in seven facilities. We calculated descriptive statistics for contaminant concentrations and computed intraclass correlation coefficients (ICC) to evaluate the variability of VOC levels indoors. We also administered a survey to collect general health information on the children attending these facilities, and information on general housekeeping practices and proximity of facilities to potential sources of target contaminants. Results: We detected six of the seven VOCs in the majority of child care facilities with detection frequencies ranging from 71% to 100%. Chloroform and toluene were detected in all samples. Median (range) concentrations for toluene, chloroform, benzene, o-xylene, ethylbenzene, and carbon tetrachloride were: 5.6 mu g/m(3) (0.6-16.5 mu g/m(3)), 2.8 mu g/m(3) (0.4-53.0 mu g/m(3)), 1.4 mu g/m(3) (below the limit of detection or <LOD - 4.4 mu g/m(3)), 1.1 mu g/m(3) ( <LOD - 35.7 mu g/m(3)), 1.0 mu g/m(3) ( <LOD - 28.5 mu g/m(3)), and 1.0 mu g/m(3) ( <LOD - 1.6 mu g/m(3)), respectively. The ICCs for the VOCs measured ranged from 0.32 to 0.75. Child care facility median concentrations for PM2.5 and PM10 were 20.1 mu g/m(3) and 26.3 mu g/m(3), respectively. Chlorine bleach, a source of chloroform, was used in almost all facilities, air fresheners and/or scented candles were used in half of the facilities, and at least one child in each facility had physician diagnosed asthma (median asthma prevalence rate=10.2%). Conclusion: We found quantifiable levels of VOCs and PM in the child care facilities sampled. Given that exposures to environmental contaminants during critical developmental stages may have long lasting impacts on children's health, larger studies are needed to characterize and identify sources of exposures to these and other indoor contaminants to develop exposure mitigation strategies. (C) 2015 Elsevier Inc. All rights reserved.