Ranohira, nestled within the Toliara region of southern Madagascar, occupies a unique geographic position. The city is situated on the edge of the Isalo National Park, a dramatic sandstone massif, and is characterized by a semi-arid climate and rugged terrain. Its coordinates (-22.4842, 45.3942) place it inland, approximately 120km from the Indian Ocean coastline. The surrounding landscape is dominated by savanna, spiny forests, and the imposing rock formations of Isalo. Ranohira’s elevation, around 800-1000m, contributes to cooler temperatures than the coastal plains, but also influences air circulation patterns. The urban character is largely defined by its role as a tourism gateway to the park, with a relatively small population of 16,041. While not heavily industrialized, local economic activity centres around tourism, agriculture (primarily subsistence farming), and some small-scale mining. The urban-rural gradient is sharp; beyond the city limits, the landscape quickly transitions to sparsely populated rural areas and the protected wilderness of Isalo. Dust from unpaved roads and agricultural practices, combined with potential emissions from wood-burning for cooking and heating, are primary local contributors to particulate matter in the air. The lack of significant industrial belts mitigates some pollution sources, but the region’s aridity exacerbates dust suspension.

Ranohira experiences a distinct wet and dry season, heavily influencing air quality. The dry season, from April to October, is characterized by consistently clear skies but also heightened dust levels. The lack of rainfall means particulate matter from unpaved roads, agricultural activities, and the surrounding savanna remains suspended in the air for longer periods. Winds, often strong during this season, can exacerbate dust storms, particularly in July and August. November marks the beginning of the wet season, bringing relief from dust but introducing the potential for increased humidity and mold spores. December to March sees the heaviest rainfall, effectively washing away much of the accumulated particulate matter and generally improving air quality. However, increased humidity can also trap pollutants closer to the ground. Temperature inversions, though less frequent than in temperate climates, can occur during cooler nights in the dry season, trapping pollutants near the surface. Sensitive groups, such as those with respiratory conditions, should be particularly cautious during the dry season, limiting strenuous outdoor activity during windy periods. The wet season generally offers better conditions for outdoor pursuits, but monitoring for mold growth is advisable. Avoiding prolonged exposure during peak dust periods (July-August) is recommended.