Impact of high particulate event on the indoor and outdoor fine particulate matter concentrations during the Southwest monsoon season

Abstract

Haze event, also known as the high particulate event (HPE) normally occurs during the Southwest monsoon season due to the high concentrations of atmospheric particulate matters including PM2.5 which are majorly caused by anthropogenic activities such as open forest and biomass burning. The impact of haze, not only on ambient air but also indoor environment, elevates with the emission of particulate matters from local transportation and industrial sources. Polluted indoor environment could impose adverse effects towards the occupants, particularly those categorized in the sensitive group. School children are among the sensitive group whom spend the majority of their time indoors, especially in school classroom and home. The present study aims to determine the indoor/outdoor ratios of PM2.5 during non-HPE and HPE. The concentrations of indoor and outdoor PM2.5 were measured continuously using a direct optical monitor (E-Sampler) and portable environmental beta-attenuation monitor (E-BAM) respectively for 24 hours. The findings revealed that the I/O ratio during HPE (0.35) was higher than the non-HPE (0.26). The Pearson correlation analysis exhibited a significant relationship (p < 0.01) between the indoor and outdoor PM2.5 concentrations with a strong correlation (r = 0.75). Therefore, it is evident that the outdoor concentrations of PM2.5 during HPE inflicted a significant impact on the indoor environment of naturally ventilated classroom due to the high I/O ratio in comparison to non-HPE, in addition to the less practical design of the classroom (open system).