Impacts of Covid-19 Lockdown on Concentration Levels of Traffic-Related Air Pollutants in Ibadan -a West African City

Trends and sources of air pollution at twenty-five traffic Intersections (TIs) before during covid-19 lockdown were investigated in Ibadan, Nigeria. The relationships among climatic parameters, vehicular counts ten pollutants which includes particulate matter (PM1, PM2.5, PM10 & Total Suspended Particles-TSP) gaseous (CO, NO2, SO2, NH3, total volatile organic compounds-TVOCs, ground level O3) measured simultaneously TIs analysed. Results indicated significant decrease mean concentrations all studied except NO2 with 212% increase the study period. Concentrations CO, TVOCs O3 reduced by 7.92%, 24.80%, 1.58%, 44.08% 4.28%, respectively while particulates PM1, TSP decreased 49.64%, 60.79%, 81.21% 84.17%, lockdown. An integrated source apportionment approach using Pearson’s correlation, Airflow backward trajectories arriving area Principal component analysis (PCA) identified emission as primary Ibadan. Emission from residences, roadside fuel combustion local transport nearby upwind areas industries farming activities secondary affecting area.