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São José da Tapera, nestled in the state of Alagoas, Brazil, occupies a position within the semi-arid transition zone of the Northeast. The city’s coordinates (-9.5578, -37.3808) place it inland, approximately 60km from the coastal influences of the Atlantic Ocean. The terrain is characterised by gently undulating hills and *chapadas* – tablelands – typical of the Brazilian Northeast. Elevation varies subtly, but generally remains below 200 meters, influencing local wind patterns and pollutant dispersion. The surrounding landscape is predominantly agricultural, with sugarcane and cassava cultivation being prominent, alongside pockets of *caatinga* scrubland. This agricultural activity contributes to particulate matter through land preparation and harvesting. The urban-rural gradient is relatively sharp; São José da Tapera is a smaller city, and the surrounding areas quickly transition to rural farmland. There are no major industrial belts directly within the city limits, however, regional industrial activity related to sugarcane processing (sugar mills and ethanol plants) can contribute to background pollution levels. The lack of significant natural barriers to air flow, combined with the inland location, means the city is susceptible to dust transport from drier areas further west. This geographical setting fundamentally shapes the city’s air quality profile, making it sensitive to both local and regional sources.

São José da Tapera experiences a distinct wet and dry season, rather than traditional four seasons. Air quality is generally better during the wet season (April to August) due to rainfall effectively scavenging particulate matter from the atmosphere. Increased humidity also suppresses dust resuspension. However, even during the wet season, localised pollution from agricultural activities can occur. The dry season (September to March) presents the greatest air quality challenges. Reduced rainfall allows dust and agricultural emissions to accumulate. The hot, dry air creates conditions conducive to temperature inversions, trapping pollutants near the ground. February and March are typically the worst months for air quality, coinciding with sugarcane harvest and burning. Strong westerly winds during the dry season can transport dust from the interior, further degrading air quality. Sensitive groups – children, the elderly, and those with respiratory conditions – should limit strenuous outdoor activity during these periods. Monitoring wind direction is crucial; winds from the west indicate higher particulate matter concentrations. Increased vigilance and preventative measures, such as using air purifiers indoors, are recommended during the dry season.