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Farafangana, nestled within the Fianarantsoa region of Madagascar, presents a unique geographic context influencing its air quality. Situated at approximately -22.8166 latitude and 47.8332 longitude, the city lies along the southeastern coast, benefiting from proximity to the Indian Ocean. The terrain is characterised by a coastal plain transitioning rapidly into the rugged, forested highlands of the eastern escarpment. This elevation change, coupled with the coastal location, creates localized weather patterns impacting pollutant dispersion. Farafangana’s urban character is that of a regional market town and administrative centre, with a relatively low population of 34,676. Surrounding the city are extensive agricultural lands, primarily focused on vanilla, cloves, and rice cultivation. These agricultural practices, while economically vital, contribute to seasonal biomass burning. The urban-rural gradient is sharp; immediately outside the town limits, dense rainforest dominates. The coastal breezes offer some natural ventilation, but the valley location can trap pollutants during periods of calm. Industrial activity is limited, but small-scale processing of agricultural products and wood fuel use are significant local sources of emissions. The city’s position within a tropical climate zone dictates high humidity and consistent temperatures, influencing chemical reactions in the atmosphere and pollutant lifetimes.

Farafangana experiences a distinct wet and dry season, profoundly impacting air quality. The wet season, roughly November to April, brings frequent rainfall and higher humidity, effectively scavenging particulate matter from the air. This period generally sees the lowest levels of airborne pollutants, though mould spores can become prevalent. However, increased rainfall also leads to soil erosion, potentially increasing dust levels during heavy downpours. The dry season, from May to October, is characterised by lower humidity and increased wind speeds, but also a surge in agricultural burning to prepare fields for planting. This practice releases significant amounts of smoke, containing particulate matter (PM2.5 and PM10) and carbon monoxide, leading to peak pollution levels, particularly in July and August. Temperature inversions, common during the cooler, drier months, can trap pollutants near ground level, exacerbating the situation. Sensitive groups – children, the elderly, and those with respiratory conditions – should limit outdoor activity during these periods. Fog, frequently occurring in the mornings during the transition seasons, can also trap pollutants. September and November offer relatively cleaner air, representing favourable times for outdoor pursuits. Monitoring wind direction is crucial; winds from agricultural areas will carry smoke into the city.