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Poção de Pedras, nestled in the southeastern Maranhão state of Brazil, occupies a geographically significant position within the Tocantins-Guaíba Basin. Located at approximately -4.75° latitude and -44.93° longitude, the city sits on a gently undulating plateau, part of the larger Brazilian Highlands. The surrounding landscape is characterized by a transition zone between the Amazon rainforest to the north and the Cerrado savanna biome to the south, resulting in a mosaic of vegetation types including gallery forests along seasonal streams and patches of cerrado vegetation. Elevation ranges from roughly 150 to 250 meters above sea level, influencing local air circulation patterns. The Itapecuru River, a vital waterway, flows nearby, moderating humidity and potentially impacting local precipitation. Poção de Pedras’ urban footprint is relatively small, exhibiting a clear urban–rural gradient as it expands outwards. While the city itself is primarily residential and commercial, the surrounding region is dominated by agriculture, particularly cattle ranching and soybean cultivation. This agricultural activity, coupled with potential small-scale processing facilities, contributes to diffuse sources of air pollutants. The city’s location, shielded somewhat by the surrounding hills, can lead to localized air stagnation, particularly during periods of calm weather. The regional climate, a tropical savanna type, with distinct wet and dry seasons, further shapes the city’s air quality profile, influencing pollutant dispersion and accumulation.

Poção de Pedras experiences a pronounced tropical savanna climate, dictating a distinct wet and dry season cycle that significantly impacts air quality. The dry season, typically spanning from June to September, is characterized by reduced rainfall, higher temperatures, and increased solar radiation. This period often sees a build-up of particulate matter, stemming from agricultural activities like controlled burns for land clearing and the resuspension of dust due to drier soil conditions. Calm wind conditions during these months exacerbate the issue, leading to localized stagnation and pollutant accumulation. Conversely, the wet season (October to May) brings frequent rainfall and higher humidity, naturally cleansing the atmosphere and dispersing pollutants. However, intense rainfall events can occasionally lead to increased levels of mold spores and associated allergens. Fog, though infrequent, can occur during cooler nights in the dry season, trapping pollutants near the ground. The transition months (May and September) are generally periods of moderate air quality, as the climate shifts between the extremes. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the dry season, limiting prolonged outdoor exposure and avoiding strenuous activities, especially during periods of visible haze. Agricultural workers should prioritize protective measures like masks and appropriate ventilation when engaging in activities that generate dust or smoke. Maintaining green spaces within the city and promoting sustainable agricultural practices are crucial for mitigating seasonal air quality fluctuations.