Backward trajectory and potential source locations of Ambient PM_2.5 at University of Lagos, Nigeria

Globally, Particulate Matter (diameter 2.5 - PM_2.5) and other pollutants have created a lot of problems health wise. It is not possible to mitigate their effects without quantifying the amount within the environment both indoors and outdoors. On this premise, the PM_2.5 within the University of Lagos (UNILAG), Nigeria (Central Laboratory and the Main gate of the campus) was evaluated with the aim of disseminating the outcome to stakeholders who would work towards mitigating the potential pollution around the surroundings. Also, a HYSPLIT model was used to track backward trajectories and the potential source locations of PM_2.5. The eight-month (2023-08-01 to 2024-03-01) air quality data were obtained from AirQo at Makerere University, Uganda. The data were subjected to Anderson—Darling Normality Testing and were compared with the National Environmental Standards and Regulations Enforcement Agency (NESREA) and World Health Organization (WHO) standards. The results were as follows. Main gate: minimum (7.23 µg/m³), maximum (180.50 µg/m³), mean (26.69), Std. (19.07), and A-Squared (104.28); Central lab: gate: minimum (6.32 µg/m³), maximum (181.13 µg/m³), mean (24.26), Std. (20.86), and A-Squared (227.28). The means of the two locations were 5.34 times (Main gate) and 4.86 times (Central Lab) higher than the WHO annual limit, while they were 1.34 times (Main gate) and 1.21 times (Central Lab) higher than the NESREA annual limit, which may likely be due to high local emissions from solid fuel combustion, waste burning, and high vehicular movements within the vicinity. The air mass came from the ocean in a southwestern direction. These findings demonstrated the significance of local emission sources in determining fluctuations in PM2.5 within the university and the necessity of focused mitigation techniques to solve serious environmental air pollution issues.