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Itaosy, nestled within the Antananarivo province of Madagascar, occupies a geographically complex position on the island’s central highlands. Located at approximately -18.9138° latitude and 47.4712° longitude, the city’s elevation, around 1,400 meters (4,593 feet) above sea level, significantly influences its climate and, consequently, its air quality. The surrounding landscape is dominated by rolling hills and valleys, part of the larger Analamanga Region, characterized by a mix of agricultural land and remnant patches of dry deciduous forest. This proximity to agricultural zones, particularly those utilizing traditional farming practices, contributes to localized particulate matter, especially during planting and harvesting seasons. The urban–rural gradient is relatively sharp; Itaosy transitions quickly from a small, densely populated settlement to agricultural fields and forested slopes. While not directly adjacent to a major river, the city benefits from seasonal rainfall patterns that contribute to humidity and can influence atmospheric stability. The broader region exhibits a limited industrial belt, with most industrial activity concentrated in Antananarivo itself, though some small-scale processing of agricultural products occurs nearby. The terrain’s undulating nature can trap pollutants, particularly during periods of low wind speed, creating localized air quality challenges. The city’s relatively small size (population 19,041) means that localized emissions from residential heating (often wood-based) and limited vehicular traffic are the primary contributors to air pollution, rather than large-scale industrial sources.

Itaosy’s air quality follows 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 due to reduced rainfall, which limits the natural cleansing effect of precipitation, and increased dust from agricultural activities and unpaved roads. Temperature inversions, common during the cooler, drier months (June-August), can trap pollutants near the ground, exacerbating the issue. The dry season’s lower humidity also contributes to the suspension of fine particles. Conversely, the wet season (November to April) brings increased rainfall, which effectively washes pollutants from the atmosphere, leading to improved air quality. However, periods of heavy fog, particularly during the transition months (November and April), can temporarily reduce visibility and trap moisture-laden pollutants. Wind patterns are generally variable, but during the dry season, periods of calm air are more frequent, hindering pollutant dispersal. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the dry season, particularly during periods of stagnant air. Outdoor activities are generally more favorable during the wet season, although heavy rainfall can still impact visibility and air quality. The agricultural cycle, with burning of crop residue common after harvests, also influences air quality, with peaks often observed in late September and October.