Health risks zonation in megacities vis-à-vis PM using GIS-based model

Abstract

In megacities, exposure to high concentrations of air pollution, as a major concern on public health, is being felt worldwide problem. The issue of particulate matter especially the PM_2.5 has become extremely crucial in Tehran, due to industrialization and population growth. Therefore, it is crucial to estimate the PM_2.5 concentrations for the purpose of health risk evaluation. Since the air quality, considering PM_2.5 varies over space and time, in this paper, RBF method in a based GIS model was utilized to zone air quality and its health risks upon PM_2.5 concentrations dispersion over Tehran, during one year, from 21 March 2013 to 20 March 2014. The RBF method was applied to obtain the zoning maps and determine the highest concentration of PM_2.5 in the 22 Tehran’s regions for each season. The RMSE_min values according to the types of functions in the RBF method, viz.: Completely regularized spline, Spline with tension, Multiquadric function, Inverse multiquadric function, and Thin-plate spline, for each month have been assessed. The numbers of neighbors in the model for each function were varied from 3 to 15.

The results indicate that the models with 4 neighbors have the best performance with the lowest RMSE values by using RBF method. In accordance with health risks assessment, the most and less favorable health conditions happen during spring and winter respectively. However, the most critical zone is city center.

Keywords: Air pollution; PM_2.5; Tehran; Health risks; GIS method; RBF model; Zonation; RMSE