Effect of COVID-19 pandemic on ambient air quality and excess risk of particulate matter in Turkey.

The COVID-19 pandemic, which has reached 4 million global cases as of March 10, 2020, has become a worldwide problem. Turkey is one of the most affected (9 in the world) country with 139 771 cases. An intermittent curfew policy that differ for three age groups, and an intercity travel ban varying within the country have been implemented. The effects of changes in social life and industrial activity in terms of environmental pollution are not yet known. The short-term effects on PM, PM, SO, NO, NO, NO, O and CO concentrations measured at 51 air quality measurement stations (AQMS) in 11 cities in March - April period of 2020 were statistically compared with that of the previous year. While PM (9/14 AQMS) and PM (29/35 AQMS) concentrations were not significantly affected, NO (12/24 AQMS), NO (20/29 AQMS), NO (17/25 AQMS) concentrations were decreased, SO concentrations at half of the AQMSs (11/25) did not show a significant change. There were stations at which higher pollutant concentrations were measured in the study period in 2020 compared to that of 2019. Excess risks associated with PM and PM were estimated to be variable, albeit with a small difference. In conclusion, the heterogeneous actions taken in response to the COVID-19 pandemic resulted in mixed effects on ambient air quality.