Abstract
The study investigated the impact of sudden frozen economy during the COVID-19 pandemic on air pollution and related health effects. The concentrations of PM10, PM2.5, SO2, O3, NO2, and CO for Air Quality Index (AQI) calculations were obtained from the Iranian Air Pollution Monitoring System in 7 provinces of central Iran between 2018 and 2021. AirQ+ software was employed to estimate health risk of respiratory mortality due to O3 exposure. AQI values decreased significantly during the lockdown (39.42%) and increased after (19.09%). Comparing to 2018–2019, air pollution in 2021 decreased by: PM2.5 4.73%, PM10 0.5%, SO2 50.4%, NO2 21.16%, and CO 10.84%. However, O3 concentrations increased during lockdown by 8.2%. Mortality due to O3 exposure increased during the lockdown comparing with the baseline in 2018–2019, except for Tehran province. Death rates due to long-term exposure to ambient O3 in investigated Iranian urban areas also increased. The use of air quality and emission standards is crucial towards the reduction of adverse health impacts associated with ambient air pollution.