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Tsianisiha, nestled within the Toliara region of Madagascar, occupies a geographically significant position on the southwestern coast. Located at approximately -22.9000 latitude and 43.5833 longitude, the city’s urban fabric is interwoven with a landscape dominated by the Mozambique Channel to the west and the drier, semi-arid plains of the Mahafaly Plateau to the east. The terrain is gently undulating, transitioning from coastal sand dunes and pockets of mangrove forest closer to the shore to slightly elevated ground further inland. This elevation, though modest, influences local wind patterns and can contribute to localized air quality variations. The surrounding landscape is characterized by a mix of scrubland, sparse acacia woodlands, and small-scale agricultural plots, primarily focused on cassava, maize, and vanilla cultivation. The urban–rural gradient is relatively sharp; Tsianisiha acts as a market town for the surrounding rural communities, drawing agricultural produce inwards. While there are no major industrial belts directly adjacent to the city, the proximity to artisanal mining operations further inland, particularly for precious stones and minerals, presents a potential source of particulate matter, especially during the dry season when dust storms are more frequent. The prevailing trade winds, influenced by the Mozambique Channel, generally blow from the east to west, impacting the dispersal of any pollutants generated within the city or carried from the interior. The coastal location also means Tsianisiha experiences a humid, tropical climate, which can trap pollutants under certain meteorological conditions.

Tsianisiha’s air quality follows a distinct seasonal pattern dictated by its tropical climate, experiencing a pronounced wet and dry season. The dry season, typically spanning from May to October, is characterized by lower rainfall and increased temperatures. This period often sees a rise in particulate matter concentrations due to increased dust lifted from the surrounding agricultural lands and the Mahafaly Plateau, exacerbated by stronger, drier winds. Agricultural burning, a common practice for land clearing and crop residue disposal, also contributes significantly to air pollution during these months. Temperature inversions, though less frequent than in cooler climates, can occasionally occur, trapping pollutants closer to the ground, particularly in the early morning hours. The wet season, from November to April, brings higher humidity and frequent rainfall, which naturally helps to cleanse the atmosphere, washing away particulate matter and reducing overall pollution levels. However, heavy rainfall can also lead to increased levels of biological pollutants like pollen and mold spores. Fog, a relatively uncommon occurrence, can occasionally form during the transition periods between seasons, trapping pollutants and reducing visibility. Outdoor activities are generally more favourable during the wet season, particularly in the afternoons after rainfall. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the dry season, limiting prolonged outdoor exposure and avoiding areas with visible dust or smoke. The intensity of the monsoon winds also plays a role, influencing the dispersal of pollutants and affecting air quality across the region.