Formaldehyde and acetaldehyde exposure and risk characterization in California early childhood education environments.

Little information is available about air quality in early childhood education (ECE) facilities. We collected single-day air samples in 2010-2011 from 40 ECE facilities serving children ≤6 years old in California and applied new methods to evaluate cancer risk in young children. Formaldehyde and acetaldehyde were detected in 100% of samples. The median (max) indoor formaldehyde and acetaldehyde levels (μg/m ) were 17.8 (48.8) and 7.5 (23.3), respectively, and were comparable to other California schools and homes. Formaldehyde and acetaldehyde concentrations were inversely associated with air exchange rates (Pearson r = -0.54 and -0.63, respectively; P < 0.001). The buildings and furnishings were generally >5 years old, suggesting other indoor sources. Formaldehyde levels exceeded California 8-h and chronic Reference Exposure Levels (both 9 μg/m ) for non-cancer effects in 87.5% of facilities. Acetaldehyde levels exceeded the U.S. EPA Reference Concentration in 30% of facilities. If reflective of long-term averages, estimated exposures would exceed age-adjusted 'safe harbor levels' based on California's Proposition 65 guidelines (10 lifetime cancer risk). Additional research is needed to identify sources of formaldehyde and acetaldehyde and strategies to reduce indoor air levels. The impact of recent California and proposed U.S. EPA regulations to reduce formaldehyde levels in future construction should be assessed.