Photochemical oxidative processing is a major aging pathway for gaseous and condensed-phase species in the atmosphere. Biomass burning organic aerosols contain many chromophores which can undergo photochemistry, changing their chemical composition and their health effects. In our group, we focus mainly on singlet oxygen

( O ). It’s the first excited state of triplet state molecular oxygen and is formed by sensitized reactions when brown carbon absorbs sunlight irradiation. Our group has been pioneering work on identifying this oxidant in organic aerosols outdoors and indoors. Our methodologies include particulate sampling and filter extractions, and we use a probe under simulated sunlight to quantify  O  steady-state concentrations and quantum yields.