Abstract: The State of Rio de Janeiro covers an area of 43,750.425 km2, ranking as the 2nd state with the highest demographic density at 365.23 inhabitants/km2. It is the 3rd most populous state in Brazil, with an estimated population of 17,463,349 people. The state boasts significant physiographic diversity, evident in various landscapes and distinct forms of anthropogenic intervention in the environment. Air quality in the state has been monitored since 1967, initiated by the former Institute of Sanitary Engineering (IES). For air quality monitoring, the Environmental Institute of Rio de Janeiro State (INEA) has divided the state into subregions: Costa Verde Region (RCV), Medio Paraiba Region (RMP), Metropolitan Region of Rio de Janeiro (RMRJ), North Fluminense Region (RNF), and Mountain Region (RS). The primary aim of this research was to provide accurate and updated information on air quality in the state of Rio de Janeiro, using data from the Official Air Quality Monitoring Network (RMQAr), comprising automatic and semi-automatic monitoring stations, spanning the years 2019, 2020, 2021, and 2022. The air quality assessment followed the standards outlined by CONAMA Resolution no 491/2018 and the National Technical Guide for Air Quality Monitoring and Assessment. The study employed various parameters to characterize meteorological conditions and measure pollutant concentrations, including air temperature, relative humidity, rainfall, total suspended particles (PTS), particulate matter with diameters of up to 10 μm (PM10) and 2.5 μm (PM2.5), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), and carbon monoxide (CO). Through RMQAr, the research gathered information on major atmospheric pollutants, their sources, concentration levels, temporal trends, and potential impacts on public health and the environment, alongside observed meteorological conditions. The results reveal that in 2019, the RMP witnessed 32 exceedances of air quality standards, followed by 30 violations in the RMRJ, 1 in the North Fluminense Region, 1 in the Costa Verde Region, and 6 in the Mountain Region. In 2020, 15 violations were identified in the RMP, with 59 in the RMRJ, and 2 in the Costa Verde Region; the Mountain Region had no violations. In 2021, 4 violations occurred in RMP, 16 in RMRJ, and 9 in RCV, with the Mountain Region presenting no violations. In 2022, the RMP had 2 violations, followed by 29 violations in the RMRJ and 2 in the RS; the Costa Verde and Mountain regions had no violations. The significant increase in total violations, approximately 97% in 2020 compared to 2019, for the pollutant ozone, is linked to the reduction in NOx emissions, primarily from vehicles. Notably, this report covers a brief pre-pandemic period and the pandemic era, discussing the effects of health measures during the COVID-19 period on air quality.

Keywords: Air Quality Monitoring, meteorological conditions, Rio de Janeiro, urban air pollution pollutants.