TEMPORY VARIATION OF PM2.5 CONCENTRATION IN BENIN CITY.

ir pollution, particularly fine particulate matter (PM2.5), is a growing environmental and public health concern in urban areas. This study aimed to compare outdoor PM2.5 concentrations during the daytime and nighttime in Benin City, Nigeria. PM2.5 data were collected from three distinct locations (Ugbowo, Sapele Road, and Etete) between October to December 2024 using PurpleAir sensors, with measurements taken six times daily at intervals of 5 hours. Statistical analysis, including paired T-test and ANOVA, was conducted to assess variations between day and night as well as across location and time. Results revealed significantly higher PM2.5 levels during the daytime, with concentrations peaking in December (170.83 µg/m³). The lowest concentration during the day was recorded in the month of October (93.67µg/m³,) while the highest concentration was in the month of December (183.33 µg/m³) at Etete. At night, the least concentration was at Sapele road in the month of October (80.09 µg/m³) with the highest in December (158.32) at Etete. A significant difference (p =1.346e-15) was recorded between the concentrations of daytime and night time PM2.5. A statistical significant difference was tested across locations (p = 0.0088) and months (p = 2e-16). The recorded concentrations far exceed WHO guidelines for PM2.5 concentrations, suggesting a possible health risk for the inhabitants of those locations. Immediate interventions are recommended, including stricter emission regulations, better urban planning, and public awareness campaigns, to mitigate the effects of air pollution and improve public health.