oa Epidemiologic implications of air pollutants in Houston, TX

The adverse health effects of high concentrations of ground-level air pollutants are well-known, but estimating exposure is difficult due to the sparseness of urban monitoring networks. This sparseness discourages the reservation of a portion of the monitoring stations for validation of interpolation techniques precisely when the risk of overfitting is greatest. In this study, we test a variety of simple spatial interpolation techniques for 8-h ozone with thousands of randomly selected subsets of data from two urban areas with monitoring stations sufficiently numerous to allow for true validation. Results indicate that ordinary kriging with only the range parameter calibrated in an exponential variogram is the generally superior method, and yields reliable confidence intervals. Based on this analysis, the temporal and spatial distributions of ambient ozone and particulate matter concentrations in Houston, TX metropolitan area during the summers of 2000-2010 were assessed. The epidemiologic implications were also examined through the analysis of children hospital's emergency room visits with focus on asthma exacerbation. The impact of demographic covariates in spatiotemporal assessments of associations of ambient air pollutant concentrations with health outcome was also examined.