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Antsahalava, a commune within the Antananarivo province of Madagascar, occupies a strategically important position within the country’s capital region. Located at approximately -19.5835° latitude and 47.4685° longitude, the area sits on the slopes of the Central Highlands, a region characterized by undulating terrain and significant elevation changes. This highland setting, averaging around 1,200 meters above sea level, profoundly influences local climate and, consequently, air quality. The surrounding landscape is a mosaic of agricultural land – primarily rice paddies and smallholder farms – interspersed with eucalyptus plantations and pockets of remnant dry deciduous forest. This proximity to agricultural zones introduces potential sources of particulate matter, particularly during burning seasons. Antsahalava’s urban character is distinctly peri-urban, exhibiting a gradual transition from dense residential areas to more rural agricultural settings. The urban–rural gradient is relatively sharp, with the immediate vicinity of Antsahalava showing a mix of traditional housing and newer constructions. While not directly adjacent to major rivers, the commune benefits from seasonal rainfall patterns that contribute to localized humidity. The broader Antananarivo region, a major industrial and commercial hub, exerts an indirect influence, with occasional transport-related pollutants drifting into the area. The topography, with its valleys and ridges, can trap pollutants, especially during periods of low wind speed, exacerbating localized air quality challenges. The prevailing winds, generally from the east, play a crucial role in dispersing or concentrating pollutants within the commune.

Antsahalava’s air quality experiences a distinct seasonal pattern dictated by Madagascar’s tropical climate, characterized by a wet and a dry season. The dry season, typically spanning from May to October, often sees a noticeable increase in particulate matter. This is largely attributable to agricultural practices, specifically controlled burns used for land clearing and crop residue removal. While these burns are a traditional practice, they contribute significantly to localized smoke and haze. Temperature inversions, common during the cooler, drier months (June-August), can trap pollutants near the ground, further degrading air quality. The wet season, from November to April, brings increased rainfall, which naturally helps to cleanse the atmosphere by washing away particulate matter. However, periods of prolonged rainfall can also lead to increased humidity and fog, which, while reducing visibility, can also trap pollutants in stagnant air. Wind patterns shift during the wet season, often becoming more variable, which can either disperse or concentrate pollutants depending on the direction and strength of the winds. During the transition months (April/May and October/November), air quality is generally more variable, influenced by the interplay of receding dry season conditions and the onset of the wet season. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the dry season, particularly during periods of agricultural burning. Limiting outdoor exertion and wearing masks can help mitigate exposure. The increased humidity during the wet season can exacerbate respiratory issues for some, so maintaining indoor ventilation is important.