Characteristics of PM 2.5 Pollution with Comparative Analysis of O 3 in Autumn–Winter Seasons of Xingtai, China.

Pollutants emission, meteorological conditions, secondary formation, and pollutants transport are the main reasons for air pollution. A comprehensive air pollution analysis was conducted from the above four aspects in the autumn–winter seasons of 2017–2018 and 2018–2019 at Xingtai, China. In addition, the relationship between PM_2.5 and O₃ was also studied from the aspects of secondary formation and meteorological conditions to find the rules of cooperative management of PM_2.5 and O₃ combined pollution. Taking measures of concentrated and clean heating and controlling biomass burning could make the concentrations of EC, K⁺ and SO₄²⁻ decrease. The variation trends of PM_2.5 and O₃ concentration in the autumn–winter season of Xingtai were different, and with the increase in secondary formation effects, the concentration of O₃ decreased. Furthermore, the key meteorological conditions that affected O₃ and PM_2.5 formation were temperature and relative humidity, respectively. The relationships of NOR (nitrate oxidation rate) and SOR (sulfate oxidation rate) against temperature presented a "U" shape, suggesting that gas-phase oxidation and gas–solid-phase oxidation were all suppressed at a temperature of around 4 °C. The cities located in the east had more pollutant transporting effects during the pollution processes of Xingtai, and the main transport routes of O₃ and PM_2.5 were not all the same. [ABSTRACT FROM AUTHOR]