Exposure to air pollution is a leading cause of global mortality. Volatile organic
compounds (VOCs) are constituents of ambient air that could exert adverse health effects.
To examine the relationship between VOC levels in ambient air and individual-level
exposure to VOCs, as assessed by urinary VOC metabolites. Secular trends in 11 ambient
air VOCs (2005–2013) and individual-level metabolites of 14 VOCs (2005–2014) were
assessed using National Monitoring Programs (NMP) and National Health and Nutrition
Examination Survey (NHANES) data, respectively. To isolate environmental exposure,
individuals reporting exposure to tobacco smoke were excluded. Quantile regression
models were used to assess secular trends in VOC exposure, and survey-weighted regression
models were built to identify factors associated with VOC exposure. All annual levels
of ambient VOCs decreased from 2005 to 2013 (Range: 12.5%–77.2%). However, 11 of the
corresponding VOC metabolites increased during the same time (Range: 0.3%–53.6%).
There was a proportional change in patterns of VOC exposure across NHANES waves, with
the middle quantiles of exposure showing the largest increase. VOC exposures were
significantly associated with age, sex, race, education, and physical inactivity,
but not with secular VOC trends. In the United States, individual-level exposure to
several VOCs increased between 2005 and 2014 despite a decline in ambient air VOC
levels. This inverse relationship suggests that ambient VOCs are not the primary source
of VOC exposure, therefore, decreasing ambient VOCs alone may not be sufficient to
protect against the adverse health effects associated with VOC exposure.