Spatiotemporal Modeling of Ozone Levels in Quebec (Canada): A Comparison of Kriging, Land-Use Regression (LUR), and Combined Bayesian Maximum Entropy-LUR Approaches

BACKGROUND: Ambient air ozone (O-3) is a pulmonary irritant that has been associated with respiratory health effects including increased lung inflammation and permeability, airway hyper-reactivity, respiratory symptoms, and decreased lung function. Estimation of O-3 exposure is a complex task because the pollutant exhibits complex spatiotemporal patterns. To refine the quality of exposure estimation, various spatiotemporal methods have been developed worldwide. OBJECTIVES: We sought to compare the accuracy of three spatiotemporal models to predict summer ground-level O-3 in Quebec, Canada. METHODS: We developed a land-use mixed-effects regression (LUR) model based on readily available data (air quality and meteorological monitoring data, road networks information, latitude), a Bayesian maximum entropy (BME) model incorporating both O-3 monitoring station data and the land-use mixed model outputs (BME-LUR), and a kriging method model based only on available O-3 monitoring station data (BME kriging). We performed leave-one-station-out cross-validation and visually assessed the predictive capability of each model by examining the mean temporal and spatial distributions of the average estimated errors. RESULTS: The BME-LUR was the best predictive model (R-2 = 0.653) with the lowest root mean-square error (RMSE; 7.06 ppb), followed by the LUR model (R-2 = 0.466, RMSE = 8.747) and the BME kriging model (R-2 = 0.414, RMSE = 9.164). CONCLUSIONS: Our findings suggest that errors of estimation in the interpolation of O-3 concentrations with BME can be greatly reduced by incorporating outputs from a LUR model developed with readily available data.