Physicochemical characteristics of PM2.5 particles during high particulate event (HPE) in school area

Abstract

Observations of fine particulate matter (PM2.5) and meteorological parameter (temperature, relative humidity and wind speed) fluctuations during a high particulate event (HPE) in Sekolah Kebangsaan Bayan Lepas, Malaysia have been conducted for three days (48 hrs). Selected sample spot of collected PM2.5 particles with high concentration was chosen to investigate the physicochemical characteristics using Field Emission Scanning Electron Microscope coupled with Energy Dispersive X-ray (FESEM-EDX). The results show that the 24 h average concentration ± standard deviation of PM2.5 (81.87 μg m−3 ± 31.83) exceeded the limit suggested by Malaysia Ambient Air Quality Standard (MAAQS-2020) and United State Environmental Protection Agency (USEPA) which is 35 μg m−3. The diurnal variations of PM2.5 concentration fluctuated significantly during HPE. Results from Pearson correlation shows that relative humidity gives the most significant influence towards PM2.5 concentration (r = 0.410; p < 0.01) followed by wind direction (r = -0.306, p < 0.01), temperature (r = -0.262., p<0.01) and wind speed (r = -0.206; p < 0.01). From a morphological and elemental analysis, it shows that PM2.5 particles collected on a filter consist of two possible sources, natural and anthropogenic sources. The element components found in the natural particles were C, O, Na, Al, Si, S, K and Fe. The major components were C, O, Al, and Si with weight percentages were 18%, 39%, 9%, and 22%. Dominant elements in anthropogenic particles were C (41%) and a significant amount of K (3%) are found which considered as biomass burning soot. Besides that, the particles also consist of O, Na, Al, Si, and Cl. In summary, particles from natural and anthropogenic sources are dominant in the ambient PM2.5 during HPE.