Chemical Composition During Severe Haze Events in Northern China

Abstract

Haze pollution in North China during winter and autumn has been rather severe in recent years due to substantial emissions from anthropogenic activities. To optimize pollution control measures and explore the formation mechanism of haze pollution, a detailed analysis of aerosol chemical compositions during severe haze events is investigated by collecting results from many studies. Secondary inorganic aerosols (primarily SNA: sulfate, nitrate and ammonium) drive the severe haze pollution evolution because the relative contributions of SNA increase rapidly with elevated pollution levels through the rapid secondary transformation of primary gaseous pollutants to secondary aerosols. Remarkably, nitrate plays an increasingly important role in PM2.5 pollution in Beijing. Organic matter (OM) is also very important for haze formation and accounts for the largest fraction. In addition, the size distribution shift is significant from the submicron to 1.1–2.1 μm due to heterogeneous formation mechanisms and hygroscopic growth.