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 (O₃), nitrogen dioxide (NO₂), and particulate matter (PM) from monitoring stations around the country to the previous 3-year average. Results indicate that O₃ was 5.6% lower and 13.7% higher than previous years during the lockdown at rural and suburban sites, respectively. NO₂ 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 NO₂ likely increased the ratio of volatile organic compounds (VOCs) to NO_x (nitrogen oxides), creating a NO_x limited environment, which resulted in an initial increase in O₃ 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 NO₂.