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Tanguá, nestled within the state of Rio de Janeiro, Brazil, occupies a strategically important position within the Baixada Fluminense, a densely populated and industrially significant region. Located at approximately -22.7300 latitude and -42.7139 longitude, the city’s geography is characterized by a gently undulating terrain, transitioning from coastal plains towards the Serra do Mar mountain range. This proximity to the mountains creates a localized valley effect, which can trap pollutants under certain meteorological conditions. The surrounding landscape is a mix of urban development, small-scale agriculture, and remnants of Atlantic Forest biome, though significantly fragmented. Tanguá sits relatively close to the Paraíba do Sul river, a vital waterway for the region, though its direct impact on local air quality is less pronounced than the influence of nearby industrial activity. The city exhibits a clear urban–rural gradient, with denser development concentrated in the central areas and gradually thinning towards the periphery, where agricultural lands and scattered rural settlements prevail. The Baixada Fluminense is a major industrial belt, encompassing petrochemical plants, steel mills, and manufacturing facilities, all contributing to potential air pollution sources. Tanguá’s location within this belt, coupled with its valley topography, makes it susceptible to the accumulation of pollutants transported from surrounding industrial zones. Elevation varies within the municipality, generally ranging from around 20 to 150 meters above sea level, further influencing local air circulation patterns and pollutant dispersion.

Tanguá’s tropical climate dictates a distinct wet and dry season pattern, significantly influencing air quality dynamics. The dry season, typically spanning from April to September, often witnesses a relative improvement in air quality due to increased wind speeds and reduced humidity. These winds help disperse pollutants, preventing their accumulation. However, this period can also be marked by increased dust from construction activities and agricultural practices, particularly during drier periods. The wet season, from October to March, brings higher humidity and frequent rainfall, which naturally scavenges pollutants from the atmosphere, leading to a temporary reduction in particulate matter. However, the increased humidity can also exacerbate the effects of gaseous pollutants, such as ozone, which forms readily in warm, humid conditions. Temperature inversions, common during the cooler months (June-August), can trap pollutants near the ground, leading to periods of poorer air quality. Fog, particularly in the mornings during the dry season, can also contribute to pollutant concentration. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should exercise caution during periods of stagnant air, especially in the mornings during the dry season and during temperature inversion events. Outdoor activities are generally more favorable during the windier months of the dry season, but vigilance is still advised, particularly near industrial areas. The transition months of March and October often present unpredictable air quality conditions, requiring careful monitoring and adaptive behaviour.