Yee Jun Tham

Abstract Chlorine atoms (·Cl) exhibit high reactivity and exert a substantial influence on the atmospheric oxidation capacity and chlorine cycle in the troposphere. The photolysis of molecular chlorine (Cl2) is a crucial source of ·Cl. However, the daytime peaks of Cl2 concentration cannot be entirely accounted for by the currently known pathways.

Abstract Nitrate comprises the largest fraction of fine particulate matter in China during severe haze. Consequently, strict control of nitrogen oxides (NOx) emissions has been regarded as an effective measure to combat air pollution. However, this notion is challenged by the persistent severe haze pollution observed during the COVID-19 lockdown when NOx levels substantially declined.