Comprehensive Particulate Matter assessment using low-cost sensors: Spatial distribution, ecological risk and health risk of inhalation exposure in the agricultural setting of Akure, Nigeria

Air pollution from particulate matter (PM) is a major global environmental health problem, especially in regions with weak air quality monitoring frameworks. This study reports an integrated assessment of PM₁ and PM₂.₅ concentrations using a low-cost PurpleAir sensor at two locations within the Federal College of Agriculture, Akure, Nigeria (Poultry Area and East Campus), and in the surrounding environment (Godogbo), with a 2-minute sampling frequency over 2 months. Statistical analysis shows that PM₁₀, PM₂.₅, and PM₁ were 4.99 µg/m³, 1.88 µg/m³, and 0.08 µg/m³ respectively. Average values were highest in the poultry area, followed by East Campus and then Godogbo, indicating the impact of farming practices on air quality in these regions. Ecological risk was assessed using the risk quotient (RQ), and all values of RQ were below unity, thus suggesting that environmental risks are not of immediate concern. However, higher values of RQ in the poultry area may represent localised emissions input. Clear variations in the spatial distribution of pollutant concentrations were demonstrated, with the poultry environment appearing to be a hotspot of pollution. Also, analysis of time series plots shows episodic spikes in particulate matter, thus suggesting that even temporary increases should be considered in assessing impact. Inhalation exposure health risk estimation revealed higher doses of PM in the poultry environment than both the East campus and Godogbo locations. All hazard quotient values were below the safety limit. The presence of PM may be of health concern for the occupants if continuous exposure persists.