Long-Range Transport and Local Emission of Atmospheric PM2.5 in Southern Region of Peninsular Malaysia

The excessive inhalation of pollutant particles with aerodynamic diameters less than 2.5 µm (PM2.5) results in risking the human respiratory health. The aim of this study is to investigate the possible pathways of long range and local tranportation for PM2.5 sources. The route patterns are analyzed by using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT 4.9) software during August 2017 to January 2018, covering three main monsoon seasons of Malaysia; southwest (SW), intermonsoon (IM) and northeast (NE) monsoon. This study represents the 72 h air mass backward trajectories in a mixed commercial-residential-industrial site of Skudai, Johor Bahru. The identified source origins are largely varied with different monsoon seasons and meteorological factors. The air-flow at different altitudes results in different effects, as the trajectory at height 500 m contributes to the greatest impact on the pollution level. The potential sources were generally from the Sumatera, Indonesia, during SW monsoon and China, during NE monsoon. The PM2.5 exceedance pattern in the Skudai area is also strongly influenced by the localized circulation, anthropogenic emission and dispersion characteristics. The increased levels of PM2.5 are predominantly contributed by the primary sources of vehicular emissions and industrial activities.