Modeling Unhealthy Air Pollution Index Using a Peaks-Over-Threshold Method

The air pollution index (API) is commonly used for describing the air quality status. Values of API are evaluated by the maximum value of five pollutants: sulfur dioxide, nitrogen dioxide, carbon monoxide, ozone (O-3), and suspended particulate matter (PM10) at a particular hour. Values that exceed the concentration of 100 are considered unhealthy. This study investigates the exceedance of API values and its dominants, using peaks-over-threshold method based on the generalized Pareto distribution (GPD), in three urban areas in Peninsular Malaysia for the period of January 2005 to December 2014. Dependency between unhealthy API and its main dominants has been evaluated by the Pickands dependence function. The GPD has been fit to all variables. The GPD fits well with all variables except O-3 in Klang and Malacca. Results obtained showed that PM10 and O-3 are the underlying pollutants of unhealthy API values in three highly polluted areas of Peninsular Malaysia. Results of study will help detect sources of air pollution and facilitate development of plans for reducing unhealthy levels of air pollutants.