Space-time smoothed indicator kriging maps of risk for PM10 in Piemonte

The Commission of the European Union, as well the United States Environmental Protection Agency (EPA) have set limit values for some pollutants in the ambient air, that have been showed to have adverse effects on human and environmental health. It is therefore important to identify areas where the risk to exceed these limit values is high. In this paper we focus on particulate matter with diameter less than 10 microns (PM10). We exploit the space-time dependence of the underlying stochastic process to evaluate the probability to exceed the limit value fixed by law. We use records of daily measurements of PM10 at 22 locations in the North-Italian region Piemonte for the year 2004. We propose a two-step semiparametric procedure for the estimation of the probability to exceed the limit value set by law. Maps of these risks for the region of interest and a validation study illustrate the findings.