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São José do Egito, nestled in the semi-arid interior of Pernambuco, Brazil, occupies a geographically significant position within the Agreste region. Located at approximately -7.4733° latitude and -37.2744° longitude, the city sits at an elevation of roughly 480 meters (1,575 feet) above sea level, contributing to a relatively dry climate. The surrounding landscape is characterized by the typical *caatinga* biome, a thorny scrub forest adapted to drought conditions, punctuated by plateaus and valleys. This vegetation, while resilient, can contribute to particulate matter during the dry season when wildfires are more prevalent. The city’s proximity to the São Francisco River, though not directly on its banks, is crucial; the river’s presence influences regional rainfall patterns and provides a vital water source for agriculture, primarily focusing on fruits and beans. This agricultural activity, while economically important, can introduce localized air pollutants from pesticide use and fertilizer application. The urban–rural gradient around São José do Egito is gradual, with small agricultural settlements and scattered rural communities blending into the broader *caatinga* landscape. There are no major industrial belts immediately adjacent to the city, minimizing direct industrial emissions. However, the regional importance of livestock farming contributes to methane and ammonia emissions, impacting local air quality, particularly in areas with concentrated animal operations. The terrain, a mix of gently sloping hills and flat plains, can influence wind patterns and the dispersion of pollutants, sometimes leading to localized stagnation during periods of calm weather.

São José do Egito experiences a distinct tropical semi-arid climate, characterized by a pronounced dry season and a shorter, less intense wet season. Air quality patterns are heavily influenced by these seasonal shifts. During the dry season (roughly May to September), characterized by minimal rainfall and high temperatures, the risk of wildfires significantly increases due to the accumulation of dry vegetation. These fires release substantial amounts of particulate matter and carbon monoxide, leading to noticeable air quality degradation. Calm wind conditions are also more frequent during this period, hindering pollutant dispersion and exacerbating the problem. The wet season (October to April) brings relief, with increased rainfall washing away particulate matter and higher humidity reducing the likelihood of wildfires. However, periods of intense rainfall can lead to soil erosion and dust storms, temporarily impacting air quality. Fog, though infrequent, can occur during cooler nights, trapping pollutants near the ground. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during the dry season, limiting outdoor activities during periods of smoke or haze. The months of August and September often experience the worst air quality due to peak wildfire risk. Conversely, March and April typically offer the best conditions for outdoor recreation. While the wet season generally improves air quality, heavy rainfall events can temporarily reduce visibility and increase respiratory irritation due to mold and dampness. Maintaining indoor air quality through proper ventilation is always recommended, particularly during periods of elevated humidity.