The variation law of air pollutant concentrations and their correlations with other factors in Huairou District, Beijing City

On the basis of 5-minute data of air pollutants SO₂, NO_x, CO and O₃and the monitoring results of PM₁₀ and PM_2.5 in Huairou District in 2019, the on hour data, daily data, daily data of each month, hourly data, daily maximum 8-hour average O₃ data, monthly data, seasonal hourly data and daily data of each season were collected. Furthermore, the influences of various factors including PM _2.5, meteorological conditions and precipitation on the concentration of air pollutants were analyzed, so as to provide data and theoretical support for relevant departments in Huairou District to formulate measures of reducing pollutant emissions, controlling urban air particulate matters and improving urban ambient air quality. The results were as follows: among the air pollutants, O₃had the maximum over-standad days, followed by PM_2.5, PM₁₀. The daily and seasonal variation characteristics of air pollutants were obvious. The characteristics of SO₂, and NO_x were similar, with the maximum concentration appearing in winter, the second in spring and autumn, and the minimum in summer. The pollution in January was the most serious. O₃had the opposite seasonal variation characteristics, with the highest value appeared in summer and the lowest value appeared in winter. The highest concentrations of PM₁₀ and PM_2.5 appeared in March (spring), followed by winter and autumn, and the lowest concentrations appeared in summer. The effect of precipitation on the removal of SO₂ and NO_x was not obvious, and it was easy to increase the concentration of air pollutants on light rainy days. On the whole, the precipitation was more efficient for the removal of NO _x than SO₂, and the removal amount of large-size particles was more than that of small-size particles.