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Queluz, a small municipality nestled within the sprawling São Paulo metropolitan region of Brazil, occupies a geographically significant position. Located at approximately -22.5372° latitude and -44.7742° longitude, it sits on a gently undulating plateau within the Serra de Jureia-Mirim mountain range, contributing to a modest average elevation of around 800 meters above sea level. This elevation, while not extreme, influences local air circulation patterns. Queluz is surrounded by a mosaic of landscapes; to the west lie agricultural zones, primarily dedicated to sugarcane and maize cultivation, while the broader metropolitan area to the east is dominated by urban sprawl and industrial activity. The urban–rural gradient is relatively sharp, transitioning quickly from residential areas to agricultural fields. The municipality itself exhibits a predominantly residential character, with limited industrial presence, though it benefits from proximity to larger industrial belts within São Paulo. The Tietê River, though not directly adjacent, flows within a reasonable distance, impacting regional hydrology and potentially influencing humidity levels, which in turn can affect pollutant dispersion. The surrounding terrain, characterized by rolling hills and valleys, can create localized areas of stagnant air, particularly during periods of low wind speed, exacerbating air quality challenges. The climate is humid subtropical, with distinct wet and dry seasons, further shaping the atmospheric conditions and pollutant behaviour within Queluz.

Queluz’s air quality experiences a pronounced seasonal cycle dictated by its humid subtropical climate. The wet season, typically spanning from October to March, brings increased rainfall and higher humidity, generally leading to improved air quality as precipitation washes away particulate matter and dilutes gaseous pollutants. However, periods of prolonged rainfall can also result in increased mold and fungal spore concentrations, impacting respiratory health for sensitive individuals. Conversely, the dry season (April to September) often witnesses a deterioration in air quality. Lower rainfall, coupled with increased solar radiation, leads to higher temperatures and a greater tendency for temperature inversions, particularly during the months of July and August. These inversions trap pollutants near the ground, intensifying their concentration. Stagnant air conditions, frequently occurring during this period, further compound the problem. The agricultural activities in the surrounding areas contribute to seasonal particulate matter, especially during harvest times. During the dry season, residents, particularly children, the elderly, and those with pre-existing respiratory conditions, should limit prolonged outdoor exertion during the early morning and late afternoon when pollutant levels are typically highest. Increased ventilation in homes and the use of air purifiers can also provide relief. The transition months (September/October and March/April) often present unpredictable air quality, influenced by shifting wind patterns and fluctuating humidity levels. Monitoring local air quality reports and adjusting outdoor activities accordingly is advisable throughout the year.