title: Non-stationary spatio-temporal modeling of traffic-related pollutants in near-road environments.
abstract: A problem often encountered in environmental epidemiological studies assessing the health effects associated with ambient exposure to air pollution is the spatial misalignment between monitors' locations and subjects' actual residential locations. Several strategies have been adopted to circumvent this problem and estimate pollutants concentrations at unsampled sites, including spatial statistical or geostatistical models that rely on the assumption of stationarity to model the spatial dependence in pollution levels. Although computationally convenient, the assumption of stationarity is often untenable for pollutants concentration, particularly in the near-road environment. Building upon the work of Fuentes (2001) and Schmidt et al. (2011), in this paper we present a non-stationary spatio-temporal model for three traffic-related pollutants in a localized near-road environment. Modeling each pollutant separately and independently, we express each pollutant's concentration as a mixture of two independent spatial processes, each equipped with a non-stationary covariance function with covariates driving the non-stationarity and the mixture weights.
authors: Department of Biostatistics, University of Michigan, School of Public Health, Ann Arbor, MI 48109, United States; Department of Environmental Health Sciences, University of Michigan, School of Public Health, Ann Arbor, MI 48109, United States.
authors: Owais
authors: O
authors: Gilani
authors: Department of Biostatistics, University of Michigan, School of Public Health, Ann Arbor, MI 48109, United States. Electronic address: berrocal@umich.edu.
authors: Veronica J
authors: VJ
authors: Berrocal
authors: Department of Environmental Health Sciences, University of Michigan, School of Public Health, Ann Arbor, MI 48109, United States.
authors: Stuart A
authors: SA
authors: Batterman
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution; D002947:Cities; D004784:Environmental Monitoring; D006801:Humans; D008824:Michigan; D015233:Models, Statistical; D062211:Spatio-Temporal Analysis; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D001335:Vehicle Emissions
keywords: Covariates-in-covariance function; Gaussian processes; MCMC algorithm; Mixture model; Non-stationary covariance function; Spatial dependence