Feedback Mechanism of Secondary Reactive Gases Generated in Photochemical Smog to Ozone Formation and Regional Photochemistry

Ground-level ozone (O3) pollution has been a long-standing environmental problem in many places of the world. No exception is Hong Kong (HK), where O3 has continued to increase since the observational data was available. From the perspective of air quality management, regional O3 pollution presents to be a growing challenge for HK, while the other major issue, i.e., street-level air pollution, is being mitigated. Reactive gases, such as nitrous acid (HONO) and formaldehyde (HCHO), play significant roles in mediating photochemistry. We attempt to fill the knowledge gap in this project through measuring HCHO and HONO, as well as other interacting pollutants, in high-O3 period, determining the secondary fractions, and modelling the impacts on O3 photochemistry.