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Parnamirim occupies a strategic position in northeastern Brazil's Rio Grande do Norte state, situated approximately 12 kilometers south of Natal, the state capital, along the Atlantic coast. The city lies within Brazil's tropical coastal zone at an elevation averaging just 53 meters above sea level, creating a flat to gently rolling terrain that facilitates urban sprawl but limits natural air circulation. Its geographic coordinates (-5.9158, -35.2628) place it squarely within the Potiguar Basin region, characterized by proximity to both the Atlantic Ocean and the Potengi River estuary, which influences local humidity patterns and occasional sea breeze ventilation. The urban landscape transitions from dense residential and commercial districts in the north toward more rural agricultural zones in the southern peripheries, where sugarcane plantations and small-scale farming contribute to seasonal biomass burning. Parnamirim's location adjacent to Greater Natal's metropolitan area creates an urban-rural gradient where pollution from vehicle emissions and construction activities in the urban core mixes with agricultural residues from surrounding farmlands. The city's position between the coastal plain and inland plateau creates microclimatic conditions where marine air masses interact with continental influences, sometimes trapping pollutants when offshore winds weaken. Its flat topography prevents natural drainage of airborne particulates, while the nearby Atlantic Ocean provides some cleansing effects through precipitation and sea breezes, though these are often insufficient during dry periods when atmospheric stagnation occurs.

Parnamirim experiences distinct seasonal air quality patterns shaped by its tropical climate with wet and dry seasons rather than traditional four-season cycles. During the dry season from September to February, reduced rainfall and increased solar radiation create optimal conditions for photochemical smog formation, with vehicle emissions from the BR-101 highway and urban construction generating elevated particulate matter levels. This period sees the highest pollution concentrations, particularly in October and November when agricultural burning in surrounding rural areas peaks before sugarcane harvesting. Sensitive groups should limit outdoor exertion during late morning and afternoon hours when ozone levels typically crest. The wet season from March to August brings substantial relief through frequent rainfall that effectively scrubs pollutants from the atmosphere, with June and July offering the cleanest air for outdoor activities. However, high humidity during this period can occasionally trap pollutants near the surface when temperature inversions develop overnight. Meteorological factors influencing air quality include the southeast trade winds that generally provide good ventilation except during periods of atmospheric stagnation, and the Intertropical Convergence Zone whose seasonal migration determines rainfall patterns. While fog is rare, haze from biomass burning sometimes reduces visibility during the dry season. The absence of significant temperature inversions due to the coastal location prevents extreme pollution episodes, but vulnerable populations should monitor local air quality reports during the dry season when respiratory irritants accumulate.