Modeling approaches linking acute health outcomes and reactive oxygen species-generating potential of ambient particulate matter

Introduction: The capacity to generate reactive oxygen species (ROS) may be an important measure of toxicity of ambient particulate matter. The dithiothreitol (DTT) assay is an assay for measuring aerosol oxidative potential. We explored several different approaches for modeling DTT activity for a large longitudinal dataset in order to assess a possible link between ROS and acute health outcomes and to determine the sensitivity of these results to modelling choices. Methods: Four predictive regression models were constructed to describe the relationships between measured DTT activity and a number of air quality indicators: particulate and gaseous species as well as meteorology. The models differ by variable selection strategy, temporal considerations, and model size. These models were then used to backcast daily DTT activity in Atlanta, GA from 1999 through 2013. Finally, these daily estimates were used in time series analyses to estimate associations with daily emergency department (ED) visits for seven ...