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Ogbomoso, situated in southwestern Nigeria's Oyo State at coordinates 8.1333°N, 4.2500°E, occupies a strategic position in Nigeria's transitional zone between the forested south and savanna north. This historic city, with a population exceeding one million, lies approximately 100 kilometers northeast of Ibadan and 150 kilometers northwest of Lagos, placing it within Nigeria's agricultural heartland yet connected to major urban corridors. The terrain features gentle undulating plains at an elevation around 350 meters above sea level, with the Ogun River basin influencing local hydrology though no major water bodies directly border the urban core. Ogbomoso's geography creates a distinct urban-rural gradient where the compact city center transitions rapidly into surrounding farmlands cultivating yams, cassava, maize, and cash crops like cocoa. This agricultural hinterland, combined with the city's position along the A1 highway linking northern and southern Nigeria, makes it a regional transport and market hub. The city's air quality is shaped by its inland location away from coastal influences, resulting in limited natural ventilation from sea breeces. Surrounding vegetation—primarily derived savanna with scattered trees—offers some particulate filtration but cannot mitigate emissions from increasing vehicular traffic, small-scale industries, residential biomass burning, and agricultural residue burning in nearby farmlands. Dust from unpaved roads during dry periods further compounds particulate pollution, while the city's bowl-like topography in certain areas can trap pollutants under stable atmospheric conditions.

Ogbomoso experiences distinct wet and dry seasons that dramatically influence air quality patterns throughout the year. From November to February, the harmattan season brings dry, dusty winds from the Sahara Desert, creating the year's worst air pollution as fine particulate matter blankets the city, reducing visibility and causing respiratory distress—particularly hazardous for children, elderly, and those with asthma or heart conditions. March through May marks the hot dry season when temperatures soar above 35°C, increasing ground-level ozone formation from vehicle emissions while agricultural burning intensifies, making late afternoon outdoor activities inadvisable for sensitive groups. The rainy season from June to September brings relief as precipitation scavenges pollutants from the air, creating the cleanest breathing conditions ideal for outdoor exercise, though high humidity can occasionally trap pollutants near the surface during brief dry spells. October serves as a transitional month with decreasing rains but harmattan dust not yet arrived, offering moderately good air quality. Sensitive individuals should monitor local haze conditions, avoid outdoor exertion during harmattan months, use air purifiers indoors when dust levels are high, and schedule essential outdoor activities for early mornings before pollution accumulates. The absence of temperature inversions typical in mountainous regions means pollution disperses more readily than in topographically constrained cities, but seasonal wind patterns and biomass burning create predictable pollution peaks requiring adaptive behaviors.