Air pollution remains a major environmental challenge, impacting air quality and human health. This study analyzes fine particulate matter (PM2.5) and its chemical composition in three regions of Rio de Janeiro: Gávea (urban area), Parque Nacional da Serra dos Órgãos (PARNASO, protected environmental area) e Campos dos Goytacazes (urban with biomass burning) focusing on BC, trace elements, soluble ions, PAH, n-alkanes and saccharides. In addition, modeling of ozone concentrations and other pollutants, and real-time monitoring of NOx emissions from heavy vehicles in the Metropolitan Region of Rio de Janeiro were performed. Samples were collected from February 2022 to June 2023 using glass fiber and quartz filters. PM2.5 concentrations varied spatially and seasonally, with the highest levels in PARNASO and the lowest in Campos. BC was more abundant in PARNASO, likely from fossil fuels and wildfire, while biomass burning dominated in Campos. SO42-, NO3-, Cl-, and Na+ were the main ions, with sulphate of anthropogenic origin. Hg levels were higher in the dry season, possibly linked to sugarcane burning. PAH and n-alkanes indicated contributions from fossil fuel combustion, with saccharides serving as tracers of biomass burning. NOx emissions from heavy vehicles varied due to weight, engine power, age, and maintenance. Atmospheric modeling showed discrepancies between simulated and observed O3 and NO2 levels, highlighting the need for improved emission profiles and VOC representation. The results emphasize the importance of monitoring, public policies, and emission control to mitigate air pollution.