Impact of COVID-19 Restriction Measures on Ambient PM 10 Concentrations during Universiti Putra Malaysia Convocation

The outbreak of COVID-19 resulted in many significant restricted social and economic activities. The pandemic provided unprecedented natural experiment in which the study was specifically conducted to investigate the impact on particulate matters with aerodynamic diameter less than 10 µm (PM 10 ) resulting from the restriction measures taken by the university management to manage COVID-19 during convocation. PM 10 and meteorological parameters (ambient temperature, relative humidity and wind speed) were monitored using TSI Dusttrak aerosol monitor and Kestrel 4500, respectively. Traffic volume was also considered as the significant source of air pollutants due to higher number of vehicles during the event. Two sets of data were collected during peak hours (7.30-9.30 a.m., 12.30-14.30 p.m. and 16.30-18.30 p.m.) on normal working days (before the outbreak in 2018) and during the convocation (after the outbreak in 2022) at two monitoring points along the major road of Persiaran Universiti 1. The results showed that ambient PM 10 concentrations were remarkably reduced by ~65-84%, especially during afternoon peak hours. Parking space allocated far from the main hall area contributed to lower PM 10 concentrations. From the parking space, graduands were required to either walk with guidance or take the provided university buses to go to the main hall. Pearson correlation analysis showed that PM 10 concentrations have significant relationship with the meteorological parameters (p