Non-photochemical Formation of Atmospheric Hazes and Rate of Sulphate Accumulation in Them

Abstract

Causes of occurrence of dense non-photochemical haze (smog) over Beijing in winter are still poorly understood. The purpose of the work is to study the catalytic oxidation of sulfur dioxide with molecular oxygen in aerosol particles and origination of dense non-photochemical haze. The rapid accumulation of \({\text{SO}}_{4}^{{2 - }}\) (tens of micrograms per m³ per h) is shown to occur only at high humidity and moisture acidity in particles (рН = 3.7–4.8) due to a transition of the catalytic (non-photochemical) air oxidation of SO₂ with participation of Fe and Mn ions into a fast degenerate branched mode. Origination of hazard atmospheric haze should necessarily be simulated accounting this catalytic reaction. The results can be used in forecasting the occurrence of dense atmospheric hazes with the aim of minimizing their dangerous consequences for human health and environment.