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São Luís do Curu, nestled in the state of Ceará, Brazil, occupies a unique geographic position within the semi-arid Sertão region. Located at -3.6700, -39.2428, the city sits on a relatively flat terrain, typical of the coastal plains extending inland from the Atlantic Ocean, approximately 60km distant. The surrounding landscape is characterised by *caatinga* vegetation – a thorny scrubland adapted to prolonged drought. This biome, while ecologically significant, contributes to dust emissions, a key factor influencing local air quality. The city’s modest population of 10,822 suggests a predominantly rural character, though increasing urbanisation is occurring. While not a major industrial hub, São Luís do Curu’s economy relies heavily on agriculture, particularly cashew and goat farming, which can contribute to particulate matter through land preparation and animal husbandry. The urban-rural gradient is relatively sharp, with agricultural lands immediately bordering the city limits. The lack of significant elevation and the proximity to the coast mean that sea breezes can play a role in dispersing pollutants, but also in transporting salt spray inland. The prevailing winds, generally from the southeast, can carry dust and agricultural aerosols into the city, impacting respiratory health. Understanding this interplay of landscape, land use, and wind patterns is crucial for assessing and mitigating air quality concerns.

São Luís do Curu experiences a distinct wet and dry season, rather than traditional four seasons. Air quality is generally poorer during the prolonged dry season, spanning from August to December. This period sees minimal rainfall, leading to increased dust resuspension from the *caatinga* and agricultural lands. The dry air and intense sunlight exacerbate particulate matter concentrations. Temperature inversions, common during the cooler nights of the dry season, trap pollutants near ground level, further degrading air quality. January to April brings the wet season, offering significant relief. Rainfall effectively washes away accumulated dust and suppresses particulate matter. However, increased humidity can promote the growth of molds and allergens, potentially impacting sensitive individuals. May to July represents a transitional period with variable conditions. Wind patterns shift, sometimes bringing in cleaner air from the Atlantic, other times stirring up local dust. For those with respiratory conditions, avoiding outdoor activity during the peak of the dry season (September-November) is advisable. Monitoring local weather reports and being mindful of dust storms is crucial. Sensitive groups, including children and the elderly, should limit strenuous outdoor exercise during dry periods and consider using air filtration indoors.