Herein, theoretical studies were performed on the atmospheric oxidation of sulfurous acid (H2SO3) and sulfite ions (HSO3−) by ozone (O3) to produce sulfuric acid and hydrosulfate ions. The most favorable path for the H2SO3 + O3 reaction has been found to be initiated from concerted H-abstraction and oxygen addition, with an overall energy barrier of 18.3 kcal mol−1. On the other hand, the most favorable path for the HSO3− + O3 reaction is initiated from oxygen addition, with an overall energy barrier of only 0.3 kcal mol−1. Kinetic simulations were performed to estimate the significance of these reactions in the formation of atmospheric sulfate and destruction of the ozone layer. The results provide new insight into the missing source of atmospheric sulfate and particulate matter.
