Overlooked Significance of Reactive Chlorines in the Reacted Loss of VOCs and the Formation of O3 and SOA

The photochemical loss of VOCs induced by OH radicals has been proven to be important for diagnosing ozone formation chemistry, while chlorine chemistry is becoming increasingly critical in the atmosphere by oxidizing primary pollutants and accelerating the formation of secondary pollutants. However, the role of the consumed VOCs caused by chlorine radicals is not clear. Here, observations combined with model simulations suggest that photochemical depletion of VOCs oxidized by chlorine radicals would not only promote the formation of ozone and oxygenated organic molecules (OOMs) but also help explain the nonlinear chemistry between secondary pollutants (O₃ and OOMs) and precursors (VOCs and NO_x). This enhancement of O₃ and OOMs by chlorine radicals is nonlinearly dependent on the ratio of VOCs to NO_x, and the connection of O₃ and secondary organic aerosol with VOCs/NO_x provides critical insight into the understanding of the oxidation processes of VOCs and intermediates from emission, reaction, and products.