Chemical composition, source distribution and health risk assessment of PM2.5 and PM10 in Beijing

Abstract

Beijing's air quality has seen significant enhancements owing to the successful implementation of China's emission control measures. However, air pollution incidents continue to occur, and more attention should be paid to continuous air quality monitoring and control. Here, the PM_2.5 and PM₁₀ samples collected during the air pollution days in Beijing in 2022 were analyzed to study the air quality situation and understand the changes in air pollution sources. The average concentration of PM_2.5 was 84.3 μg/m³ and PM₁₀ was 128.7 μg/m³. NO₃⁻, SO₄²⁻ and NH₄⁺ were the primary constituents of water-soluble inorganic ions, with concentrations of 18.8 μg/m³, 7.9 μg/m³, 7.4 μg/m³ in PM_2.5, and 20.5 μg/m³, 9.3 μg/m³, and 8.1 μg/m³ in PM₁₀. The enrichment factor values for Sn, Sb, and Cd in PM_2.5 exceeded 100, indicating severe anthropogenic pollution. Five pollution factors for PM_2.5 and PM₁₀ were obtained from the analysis of PMF model: vehicle emissions and dust, industrial emissions, secondary inorganic aerosols, coal combustion, and electronic manufacturing. The highest contributing factors were vehicle emissions and dust (28 % for PM_2.5 and 34 % for PM₁₀). According to the health risk assessment, Mn presented a non-carcinogenic risk to humans. Cd, As, Ni, and Cr (VI) showed a low level of carcinogenic risk within the acceptable range. The backward trajectory analysis showed that air masses from nearby cities exhibited stronger pollutant capabilities. Combining the potential source contribution function and concentration weight trajectory diagrams, the main potential source areas of Beijing are in Hebei, Tianjin, Shanxi and Henan.