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Manohisoa, nestled within the Antananarivo province of Madagascar, occupies a geographically complex position at approximately -19.7867 latitude and 46.7924 longitude. The city’s location, with an elevation of around 1,350 meters (4,430 feet) above sea level, places it within the Central Highlands, a region characterized by undulating terrain and steep slopes. This highland setting significantly influences local 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 Manohisoa itself is a relatively small settlement with a population of 15,422, it’s situated within a broader agricultural zone, meaning agricultural burning practices, particularly during land clearing and harvest seasons, can contribute to localized particulate matter pollution. The city’s proximity to Antananarivo, the national 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 significant nearby bodies of water limits the natural cleansing effect of humidity and rainfall, which are crucial for pollutant removal. Topography plays a key role; the surrounding hills can trap pollutants, especially during periods of low wind, leading to stagnant air conditions and increased concentrations of airborne particles. The prevailing winds, often influenced by regional weather patterns, can either disperse pollutants or exacerbate localized air quality issues depending on their direction and strength.

Manohisoa’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 presents the most challenging air quality conditions. Reduced rainfall means fewer opportunities for natural pollutant washout, and lower humidity contributes to increased particulate matter concentrations. Temperature inversions, common during the cooler nights of the dry season, trap pollutants close to the ground, intensifying localized air pollution. Agricultural burning, a prevalent practice for land preparation, peaks during this period, releasing significant amounts of smoke and particulate matter into the atmosphere. Conversely, the wet season, from November to April, brings increased rainfall and higher humidity, naturally cleansing the air and reducing pollution levels. Stronger winds associated with the monsoon season also help disperse pollutants. Fog, which can occasionally form in the highlands, can temporarily trap pollutants, but the overall effect of the wet season is a significant improvement in air quality. Outdoor activities are generally best enjoyed during the wet season months, particularly from February to March. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the dry season, minimizing prolonged exposure to outdoor air, especially on days with visible smoke or haze. Maintaining indoor air quality through ventilation and air purification can also be beneficial during periods of elevated pollution.