Impact of COVID-19 lockdown on particulate matter (PM₂.₅) concentration in Kathmandu, Nepal

ABSTRACT

This paper reports a study on the statistics for particulate matter pollution (PM₂.₅) and the COVID-19 lockdown in the Kathmandu valley. The PM₂.₅ decreased during the COVID-19 pandemic lockdown periods 2020 compared to the average value of the previous three years (2017, 2018, and 2019). Further, analysis of active fire and air mass trajectory for April and May in 2019 and 2020 shows that the particulate matter trend associated with Kathmandu is not directly influenced by the long-range transport of wind carrying aerosols from the active fire regions. Statistical tests indicate a reduction of particulate matter pollution during the period.