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Quixeré, nestled in the heart of Ceará state, Brazil, occupies a strategic position within the densely populated and economically vibrant Northeast region. Located at approximately -5.0739° latitude and -37.9889° longitude, the city’s geography is characterized by a gently undulating terrain typical of the Sertão biome, a semi-arid region punctuated by occasional seasonal streams and pockets of vegetation. The surrounding landscape is predominantly scrubland and *caatinga*, a unique thorny woodland adapted to the arid climate, with sparse agricultural activity concentrated along the few available water sources. Quixeré sits relatively low in elevation, averaging around 300 meters above sea level, which can influence atmospheric stability and pollutant dispersion. While not directly adjacent to a major river, the city benefits from proximity to the Rio Salgado, a seasonal waterway that, during periods of rainfall, provides a vital source of water and influences local humidity. The urban–rural gradient around Quixeré is gradual, transitioning from the built environment to scattered rural settlements and extensive *caatinga* vegetation. The city’s regional position, situated between larger urban centers like Fortaleza and Sobral, means it experiences some spillover effects from their industrial and transportation activities, though these are generally less pronounced. The prevailing winds, typically from the northeast, play a crucial role in ventilating the area, but can also carry pollutants from distant sources. The soil composition, largely sandy and porous, impacts the retention of dust and particulate matter, contributing to localized air quality challenges, particularly during dry periods.

Quixeré’s tropical climate dictates a distinct wet and dry season pattern, profoundly impacting its air quality. The dry season, typically spanning from August to May, is characterized by intense solar radiation, high temperatures, and minimal rainfall. This period often witnesses a build-up of particulate matter, primarily dust originating from the surrounding *caatinga* and agricultural lands, exacerbated by wind erosion. Temperature inversions, common during the cooler nights of the dry season, can trap pollutants near the ground, leading to localized episodes of reduced air quality. The months of September through November are particularly susceptible to these conditions, making outdoor activities for sensitive individuals, such as children and the elderly, potentially problematic. Conversely, the wet season, from May to August, brings relief through frequent rainfall, which effectively washes away accumulated pollutants and increases atmospheric humidity, improving air quality. Stronger winds associated with occasional thunderstorms also aid in dispersing any remaining contaminants. Fog is rare, but when it does occur, it can temporarily reduce visibility and trap pollutants. During the wet season, agricultural activities increase, potentially leading to localized emissions from machinery and fertilizer application, though these are generally short-lived. The increased vegetation cover during this period also helps to absorb some pollutants. Individuals with respiratory conditions should monitor local conditions and limit strenuous outdoor activity during periods of high dust concentration, especially during the dry season’s peak.