Contribution of hydroxymethanesulfonate (HMS) to severe winter haze in the North China Plain

. Severe winter haze accompanied by high concentrations of fine particulate matter (PM2.5) occurs frequently in the North China Plain and threatens public health. Organic matter (OM) and sulfate are recognized as major components of PM2.5, while atmospheric models often fail to predict their high concentrations during severe winter haze due to incomplete understanding of secondary aerosol formation mechanisms. By using a novel combination of...