Characterization of a smog chamber for studying formation of gas-phase products and secondary organic aerosol.

Smog chambers provide a potent approach to explore the secondary organic aerosol formation under varied conditions. This study describes the construction and characterization of a new smog chamber facility for studying the formation mechanisms of gas-phase products and secondary organic aerosol from the photooxidation of volatile organic compounds. The chamber is a 5.4 m Fluorinated Ethylene Propylene (FEP) Teflon reactor with the potential to perform photooxidation experiments at controlled temperature and relative humidity. Detailed characterizations were conducted for evaluation of stability of environmental parameters, mixing time, background contamination, light intensity, and wall losses of gases and particles. The photolysis rate of NO (J) ranged from (1.02-3.32) ×10 sec, comparable to the average J in ambient environment. The wall loss rates for NO, NO, and O were 0.47 × 10, 0.37 × 10, and 1.17 × 10 min, while wall loss of toluene was obsoletely found in a 6 hr test. The particle number wall loss rates are (0.01-2.46) ×10 min for 40-350 nm with an average lifetime of more than one day. A series of toluene photooxidation experiments were carried out in absence of NO under dry conditions. The results of the simulation experiments demonstrated that the chamber is well designed to simulate photolysis progress in the atmosphere.