Experience of Substantiation and Results of Monitoring of Priority Air Pollutants in Norilsk within the Federal Clean Air Project

Introduction: Long-term multicomponent ambient air pollution in residential areas is one of the serious threats to human health. The Federal Clean Air Project implemented within the National Ecology Project aims at fundamental improvement of the quality of life of the Russian population through reduction in emissions of priority (hazardous) pollutants posing the highest health risks. 
Objective: To substantiate the choice and to analyze the results of monitoring of priority air pollutants in the city of Norilsk included in the Project. 
Materials and methods: Priority chemicals were determined based on the results of a health risk assessment. The exposure was assessed on the basis of dispersion calculations using a consolidated database of stationary and mobile emission sources (1,970 sources from 110 enterprises and 175 sections of the urban road network) and the “Ecologist – City” 4.60.1 software with the “Average” calculation block, realizing atmospheric dispersion modeling techniques approved in the Russian Federation. The airborne pollutant accounting for at least 95 % of the unacceptable carcinogenic and/or non-carcinogenic risk was considered a priority. The estimates were then verified by the results of measuring ambient concentrations of 20 pollutants within socio-hygienic air quality monitoring in Norilsk for 2020–2021. 
Results: We established that both short- and long-term exposure to air pollutants posed unacceptable health risks to more than 180 thousand people affected. The list of priority contaminants subject to monitoring and priority regulation comprised ten chemicals, including nitrogen oxide and dioxide, sulfur dioxide, particulate matter, sulfuric acid, carbon oxide, copper oxide, nickel compounds, lead and its compounds, and benzene, of which seven were confirmed as such by the monitoring data. In fact, the measured concentrations of sulfur dioxide, particulate matter, copper and nickel compounds at a number of sites were significantly higher than those estimated by dispersion modeling. Vapors of sulfuric acid, carbon monoxide and nitrogen oxide were below the limit of detection. 
Conclusions: The health risk assessment methodology used for selecting priority air pollutants is an adequate and effective tool of environmental management. Verification of the lists of priority chemicals compiled on the basis of dispersion modeling using the merged database on the urban sources of air pollution is expedient and necessitates improvement of techniques and mechanisms for stocktaking of emission sources. A significant discrepancy between the estimated and measured data on pollution levels should be discussed by all interested parties and result in changes to the consolidated databases and an increase in the accuracy of subsequent hygienic assessments, including that of public health risks.