Research news on photochemical air pollution

Photochemical air pollution is an atmospheric phenomenon in which primary pollutants, principally nitrogen oxides (NOx) and volatile organic compounds (VOCs), undergo sunlight-driven photochemical reactions to form a complex mixture of secondary pollutants. Key products include ozone (O₃) in the troposphere, peroxyacyl nitrates (PANs), aldehydes, organic nitrates, and secondary organic aerosols. These reactions are initiated by NO₂ photolysis, generating ozone and radical species (e.g., OH, HO₂, RO₂) that propagate non-linear reaction chains. Photochemical air pollution is characterized by strong diurnal and seasonal patterns and is sensitive to precursor emissions, meteorology, and atmospheric oxidizing capacity.