Effect of COVID-19 lockdown on regional pollution in Ireland.

This study examines the regional impact of the COVID-19 lockdown restrictions on pollution in Ireland by comparing the 2020 measurements of ozone (O), nitrogen dioxide (NO), and particulate matter (PM) from monitoring stations around the country to the previous 3-year average. Results indicate that O was 5.6% lower and 13.7% higher than previous years during the lockdown at rural and suburban sites, respectively. NO decreased by 50.7% in urban areas, but increased slightly in agricultural regions, consistent with satellite observations. PM concentrations did not change significantly compared to previous years; however, a reduction in the signal variability in the smaller size particle measurements may be the result of different emission sources. The reduction in NO likely increased the ratio of volatile organic compounds (VOCs) to NO (nitrogen oxides), creating a NO limited environment, which resulted in an initial increase in O in suburban areas, and the lower than usual levels observed at rural sites. Meteorology showed higher than average wind speeds prior to lockdown, which likely acted to disperse PM and NO.