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Ampahimanga, nestled within the Antananarivo Province of Madagascar, occupies a geographically significant position at approximately -19.1046° latitude and 47.2004° longitude. The city’s location, with an elevation of around 1,350 meters (4,430 feet), places it within the Central Highlands, a region characterized by undulating terrain and steep slopes. This highland setting profoundly influences its microclimate and, consequently, its air quality. The surrounding landscape is a mosaic of terraced rice paddies, smallholder farms cultivating maize and beans, and patches of remnant forest, creating a distinct urban–rural gradient. While Ampahimanga itself is a relatively small settlement with a population of 16,184, it’s situated within a broader agricultural zone, meaning agricultural practices, including burning of crop residues, can contribute to localized air pollution events. The city’s proximity to Antananarivo, Madagascar’s capital, means it experiences some spillover effects from the larger urban center’s industrial activity and traffic emissions, though to a lesser degree. The lack of major nearby bodies of water limits the natural cleansing effect of humidity and precipitation, and the topography can trap pollutants, particularly during periods of calm weather. The prevailing winds, often channeled through the highland valleys, can either disperse pollutants or concentrate them depending on their direction and strength, creating variable air quality conditions across the settlement. The surrounding hills act as a barrier, influencing airflow patterns and potentially exacerbating localized pollution.

Ampahimanga’s air quality follows a distinct seasonal pattern dictated by Madagascar’s tropical climate, exhibiting a clear wet and dry season cycle. The dry season, typically spanning from May to October, often sees a build-up of particulate matter. Reduced rainfall during this period means fewer opportunities for atmospheric cleansing through precipitation. Furthermore, agricultural burning, a common practice for land preparation, intensifies during the dry season, releasing significant quantities of smoke and pollutants into the air. Temperature inversions, where cooler air becomes trapped beneath a layer of warmer air, are more frequent during the dry season, particularly in the mornings, preventing pollutants from dispersing vertically. The months of July and August are generally considered periods of heightened air quality concern due to the combination of agricultural burning and stable atmospheric conditions. Conversely, the wet season, from November to April, brings increased rainfall and higher humidity, which naturally washes pollutants from the atmosphere and increases the efficiency of pollutant removal. Stronger winds associated with the monsoon season also help to disperse pollutants. While the wet season generally offers improved air quality, periods of dense fog can temporarily trap pollutants near ground level. 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 smoke. During the wet season, while generally better, periods of fog necessitate similar precautions.