Industrial Dominance of Urban NO2 and Associated Health Risks: A Multi-Source Analysis in the Southern Region of Rio de Janeiro State

Driven by regional demand for stringent emission controls and the associated public health impacts, this study investigates tropospheric NO2 concentrations in Volta Redonda, a major metallurgical hub in Rio de Janeiro State. Initially, TROPOMI data were used to establish spatiotemporal patterns from 2019 to 2024, revealing that Volta Redonda maintains higher NO2 levels than similarly sized urban centers. A detailed analysis of the ‘weekend effect’ showed a minimal 3% reduction in NO2 concentrations during the weekend in Volta Redonda, compared with a 23% drop in Rio de Janeiro city, suggesting that industrial sources of this pollutant predominate over vehicular traffic. This finding is further supported by an analysis of Climate TRACE emissions data, which shows that industrial NOx emissions exceed transportation emissions in this industrial-urban cluster. Local ground station measurements, combined with satellite observations, indicate that the nearby industrial zone is likely the primary source of NO2. Finally, the study quantifies the human cost through a Relative Risk Index (RRI) analysis. Results indicate that a 1 µg/m3 increase in minimum NO2 concentrations leads to a 34% rise in pediatric hospitalizations and a 25% increase among older people, offering critical evidence for regional emission regulations and public health strategies.