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Anjiamangirana I, nestled within the Mahajanga province of Madagascar, occupies a geographically significant position on the Mozambique Channel coastline. Located at approximately -15.1669 latitude and 47.7786 longitude, the city’s terrain is characterized by a gently sloping landscape transitioning from coastal plains to low hills inland. This gradual elevation change influences local wind patterns and the dispersion of pollutants. The proximity to the Mozambique Channel is a defining feature, moderating temperatures and introducing maritime influences on air quality, occasionally bringing in sea salt and moisture. The surrounding landscape is a mosaic of coastal forests, mangrove swamps, and extensive agricultural zones, primarily focused on vanilla, rice, and cashew cultivation. These agricultural practices, while vital to the local economy, can contribute to localized air pollution through the use of fertilizers and the burning of agricultural waste, particularly during harvest seasons. The urban–rural gradient around Anjiamangirana I is relatively smooth, with small villages and agricultural plots interspersed within the broader landscape. There are no major industrial belts immediately adjacent to the city, but Mahajanga, a larger urban center approximately 20 kilometers to the north, exerts an influence, with occasional transport-related emissions impacting air quality. The prevailing winds generally blow from the east, carrying moisture and potential pollutants from the channel inland, while the topography subtly directs airflow, creating localized areas of stagnant air, especially during periods of calm weather. The city’s relatively small size (population 12,000) means that localized sources, such as cooking fires and vehicle emissions, are the primary drivers of air quality concerns.

Anjiamangirana I experiences a tropical climate with distinct wet and dry seasons, significantly impacting its air quality profile. 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 increased solar radiation, which can exacerbate photochemical smog formation if precursor pollutants are present. During the dry season, periods of calm weather and temperature inversions – where cooler air is trapped beneath a layer of warmer air – are more common, leading to stagnant air and the concentration of pollutants near the surface. Months like July and August, with consistently low rainfall and stable atmospheric conditions, are often periods when air quality is most likely to be affected by local sources. The prevailing easterly winds, while generally beneficial for dispersion, can occasionally become weak during these months, further contributing to pollutant accumulation. Sensitive groups, such as children, the elderly, and individuals with respiratory conditions, should exercise caution during these periods, limiting strenuous outdoor activity and ensuring adequate ventilation indoors. The increased use of biomass fuels for cooking during the dry season, a common practice in the region, also contributes to indoor and outdoor air pollution, necessitating improved ventilation and alternative cooking methods.