Characteristics of atmospheric air pollution by fine particles based on regional monitoring data

Abstract

Introduction. Air pollution with particulate matter (PM) is a serious global problem. In the Russian Federation, regular field measurements of PMs in the ambient air are carried out only in a few cities, and the data, as a rule, are not systematized. Aim of the study: long-term analysis of the data set on concentrations of fine particles in the ambient air of the city of Kazan. Material and methods. Long-term analysis of ambient air pollution by fine particles in the city of Kazan for the period from 2016 to 2020 has been carried out. To study the effect of separate factors (year, measurement time during the day, climatic conditions, the presence of other pollutants) on the levels of PM10 and PM2.5, regression analysis was applied based on the method of mixed models. To characterize the elemental composition of the PM2.5 fraction, sampling of atmospheric air on PVC filters was carried out by use of 100 NR impactor (TSI, USA). The step function and MPPD model were applied to calculate the number of particles and the mass of the deposited fraction of fine particulate matter in different regions of the human respiratory tract. Results. The PM10 concentrations remained stable over a 5-year period, while the PM2.5 concentrations decreased. At the same time, an increase in the maximum annual concentrations of both fractions was observed. The concentrations of PM10 and PM2.5 significantly depended on climatic conditions. The presence of nitrogen oxides and organic carbon in the ambient air was significantly associated with higher concentrations of PM10 and PM2.5. The elemental composition of PM2.5 fraction was represented mainly by carbon (C) (from 86.16% to 93.45%). Mathematical modeling has shown that PM10 is mainly deposited in the upper respiratory tract, and their presence in the tracheobronchial and alveolar zones is insignificant. PM2.5 particles reach the lower respiratory tract and alveolar area. Conclusion. A statistically significant upward long-term trend in the maximum annual ambient concentrations for both fractions of fine particles can increase health risks. Secondary pollutants (nitrogen oxides, organic carbon) are important factors for the formation of secondary particles in the ambient air. The results obtained indicate that when assessing the risks to public health, it is necessary not only to use the concentrations of fine particles in ambient air, but also to consider the degree of deposition of separate fractions in different parts of the human respiratory tract, considering the alleged pathogenesis and priority target cells characteristic of individual diseases.