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Karoi, situated in Mashonaland West Province, Zimbabwe, occupies a pivotal position within the country’s agricultural heartland. Located at approximately -16.8100 latitude and 29.7000 longitude, the town lies on a relatively flat plateau, part of the Highveld, at an elevation of around 900-1000 meters. This terrain contributes to temperature inversions, a key factor in trapping pollutants. The surrounding landscape is dominated by commercial farming, particularly tobacco, maize, and cotton, creating a significant agricultural zone. The town is not directly adjacent to a major body of water, though the Hunyani River flows nearby, influencing local humidity. Karoi serves as a crucial market and processing centre for the region’s agricultural output. The urban-rural gradient is pronounced; the town itself is a concentrated area of activity, while the surrounding areas are largely rural and agricultural. This proximity to extensive agricultural practices introduces potential sources of particulate matter from land preparation, harvesting, and curing processes, particularly tobacco. Limited industrial activity exists within Karoi itself, but transport corridors passing through the town contribute to vehicular emissions. The prevailing winds, influenced by the regional topography, play a crucial role in dispersing – or concentrating – these pollutants.

Karoi experiences a distinct wet and dry season, heavily influencing its air quality. The dry season, from May to October, is typically characterised by lower rainfall and increased dust levels, leading to a peak in particulate matter (PM10 and PM2.5). Agricultural activities, such as land preparation for the next planting season and tobacco curing, exacerbate this, releasing smoke and dust into the atmosphere. Temperature inversions are more frequent during the cooler mornings of the dry season, trapping pollutants near ground level. November to April marks the wet season, bringing relief from dust and a reduction in agricultural smoke. However, increased humidity can promote the formation of secondary pollutants. Rainfall effectively washes particulate matter from the air, improving air quality. March and April, towards the end of the wet season, can experience localised flooding, potentially releasing pollutants from disturbed soil. Sensitive groups – children, the elderly, and those with respiratory conditions – should exercise caution during the dry season, particularly August and September, and consider limiting strenuous outdoor activity. The wet season generally offers better conditions for outdoor pursuits, though monitoring for localised flooding and potential waterborne pollutants is advisable. Wind patterns shift with the seasons, impacting pollutant dispersion.