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Ambinanisakana, nestled within the Toamasina Province of Madagascar, occupies a geographically significant position along the eastern coast. Located at approximately -16.9884° latitude and 49.4786° longitude, the town’s immediate surroundings are characterized by a blend of coastal plains and gently undulating terrain, rising gradually inland. The proximity to the Indian Ocean exerts a profound influence on the local climate and, consequently, air quality. To the east lies the expansive ocean, providing a natural ventilation pathway, though also introducing marine aerosols. Westward, the landscape transitions into a mosaic of agricultural lands, primarily focused on clove, vanilla, and rice cultivation – these activities contribute to localized particulate matter and volatile organic compound (VOC) emissions. The urban–rural gradient is relatively sharp; Ambinanisakana itself is a small town, but its connection to Toamasina, a major port city and industrial hub approximately 30 kilometers north, means it experiences some spillover effects from industrial activity and increased traffic. The elevation is relatively low, rarely exceeding 30 meters above sea level, which can exacerbate temperature inversions, trapping pollutants closer to the ground. The surrounding landscape is dominated by coastal forests and mangrove ecosystems, which, while beneficial for carbon sequestration, can also contribute to biogenic VOC emissions. The town’s location within a humid tropical climate zone further influences atmospheric stability and pollutant dispersion.

Ambinanisakana’s air quality follows a distinct seasonal pattern dictated by its tropical climate, experiencing a pronounced wet and dry season rather than four traditional seasons. The dry season, typically spanning from May to October, often sees a slight increase in particulate matter concentrations. This is due to reduced rainfall, which limits the natural cleansing effect of precipitation, and increased agricultural burning practices as farmers prepare fields for the next planting cycle. Wind patterns during this period can be variable, sometimes leading to stagnant air conditions, particularly during periods of high pressure, which can trap pollutants. The wet season, from November to April, brings frequent rainfall and higher humidity, generally leading to improved air quality as pollutants are washed from the atmosphere. However, periods of intense rainfall can also lead to increased fungal spore counts, impacting respiratory health. Fog, a relatively common occurrence during the transition months (October/November and April/May), can significantly reduce visibility and trap pollutants near the ground. Temperature inversions, where cooler air sits below warmer air, are less frequent than in temperate climates but can occur, particularly during the dry season, leading to localized air quality degradation. Sensitive groups, such as children, the elderly, and individuals with pre-existing respiratory conditions, should exercise caution during the dry season, particularly when agricultural burning is prevalent. Outdoor activities are generally more favorable during the wet season, although vigilance regarding fungal spore counts is advised.