Abstract: 

Understanding the fate and composition of atmospheric particulate matter (PM) is critical for public health, air quality, and climate. PM can either be directly emitted or secondarily generated from the oxidation of gases, producing secondary aerosols. Reactive species, including reactive oxygen species (ROS) and environmentally persistent free radicals (EPFR) that are contained within and are generated from PM, play important roles in adverse health effects and chemical transformations in the atmosphere. In general, particulate matter composition varies greatly with source and atmospheric conditions, and as a result not all PM yields the same concentration of reactive species. Here we determine the effect of nitrogen oxides (NO_x) on the generation of EPFR and ROS from laboratory generated secondary organic aerosol (SOA). Subsequently, we evaluate the effects of photolytic and oxidative aging of SOA on EPFR and ROS yield. For the third study, we investigate EPFR formation from outdoor PM_2.5 collected in Fairbanks, Alaska where subarctic conditions, frequent temperature inversions, and local emissions create a unique environment. Lastly, we evaluate superoxide production in vitro from macrophage cells exposed to various types of PM. Together these studies demonstrate that the type of PM, as well as the environment in which it is generated, can have significant impacts on its EPFR concentration and ROS yield upon dissolution or inhalation.