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Marojala, nestled within the Antsiranana Province of Madagascar, occupies a geographically significant position on the island’s northeastern coast. Located at approximately -14.4680 latitude and 50.0320 longitude, the town’s setting is defined by a gentle slope rising from the Indian Ocean, creating a microclimate influenced by both maritime and inland conditions. The surrounding landscape is a tapestry of coastal scrubland, transitioning into the verdant slopes of the Anjanaharibe-Sud Special Reserve, a region characterized by dense rainforest and significant biodiversity. This proximity to a protected area, while ecologically valuable, can also influence air quality through the release of biogenic volatile organic compounds (BVOCs), particularly during warmer months. The town’s elevation is relatively low, averaging around 30 meters above sea level, which limits dispersion of pollutants and can exacerbate ground-level concentrations. Marojala’s coastal location means it experiences consistent sea breezes, which generally provide some natural ventilation, though their effectiveness is dependent on prevailing wind patterns. The urban–rural gradient is relatively sharp; the town itself is small, with a population of approximately 13,000, quickly giving way to agricultural lands and the rainforest. While there are no major industrial belts immediately adjacent to Marojala, the region supports small-scale agriculture, primarily vanilla and clove cultivation, and some fishing activity, which could contribute localized emissions. The terrain’s gentle slope and coastal exposure combine to create a unique atmospheric environment, impacting how pollutants behave and disperse within the town’s boundaries.

Marojala’s tropical climate dictates a distinct wet and dry season pattern, profoundly influencing its air quality. The wet season, typically spanning from November to April, brings frequent rainfall and high humidity. While the rain naturally helps to cleanse the atmosphere by removing particulate matter, the increased humidity can trap pollutants closer to the ground, particularly during periods of reduced wind. The dry season, from May to October, is characterized by lower rainfall and generally clearer skies. However, this period often sees a build-up of pollutants due to reduced precipitation and potentially stagnant air conditions. During the dry season, particularly in August and September, temperature inversions can occur, where a layer of warm air sits above cooler air near the ground, preventing vertical mixing and trapping pollutants. Sea breezes, a constant feature, are often weaker during the dry season, further limiting dispersion. The months of July and August are generally considered periods when outdoor activities should be approached with caution, especially for individuals with respiratory sensitivities. The surrounding rainforest releases significant BVOCs throughout the year, but these emissions can be more noticeable during the warmer, drier months. Sensitive groups, including children, the elderly, and those with pre-existing respiratory conditions, should be particularly mindful of air quality during the dry season and avoid prolonged exposure to outdoor air during periods of stagnant conditions or noticeable haze. Increased agricultural burning, though regulated, can also contribute to localized air pollution during the transition periods between seasons.