Impact of the COVID-19 on ambient air particulate matter in Surabaya, Indonesia

This study investigates atmospheric pollutants, especially fine particulates in Surabaya, Indonesia from 2018 to May 2020, as well as the impact of the COVID-19 event on air quality. Sampling was carried out using a Gent stacked filter sampler which is able to collect airborne particulate samples in fine size fractions (<2.5 µm). The mass concentration of fine particulates was determined gravimetrically, while the chemical composition was carried out by nuclear analytical techniques, especially those based on XRF. To prevent the spread of the Corona virus, the Indonesian government has implemented a large-scale social restriction (LSSR) policy. This paper discusses the impact of the implementation of the LSSR on air quality in Surabaya, especially in the period 28 April - 25 May 2020. The average concentration of PM2.5 during the implementation of the LSSR in May 2020 showed a decrease of 22.6% compared to April 2020. Compared to the concentration in the same month from the previous 2 years (2019 and 2018), PM2.5 in May 2020 decreased by 7.3 and 15.3%, respectively. As for Black Carbon (BC), the decreases were 26.2 and 46.4%, respectively. For the concentrations of heavy metals Pb, Zn, Fe, Cu, Mn, the reduction varies between 28-76% and 49-81%, respectively. The positive impact of the LSSR policy can be clearly demonstrated on air quality in May 2020, where there was a significant reduction in the concentrations of PM2.5 and BC, as well as their chemical composition. This decrease occurred due to the reduction in various anthropogenic activities such as transportation and industrial activities. These results can be taken into consideration in evaluating and formulating effective policies for improving air quality in Surabaya and its surroundings.