Biomass burning is an increasingly important source for organic compounds in the atmosphere, especially with current trends towards a warmer, drier climate in the Northwest. When transported to urban areas, these chemicals can contribute to air quality exceedances, with negative impacts on human health. Progress is being made to better understand how wildfire emissions vary for different burns as well as how the smoke plume evolves, or ages, after it is emitted. However, despite a range of laboratory and ambient studies, there is a lack of understanding of the rate at which the brown color of smoke particles will bleach in the atmosphere. In addition, there is little information on the volatile organic compounds produced during aging and the physical properties of very aged smoke particles. This project proposes a laboratory study to probe the aging of biomass burning organic aerosol particles under different environmental conditions. The team will measure changes in both the condensed phase and the gas-phase during longer term photolysis and heterogeneous oxidation experiments. This study also makes use of previously collected filter samples from both Fire Influence on Regional and Global Environments Experiment (FIREX) 2016 and 2019, expanding the context for the FIREX campaigns. The combined results will provide a more complete view of the impact of aged BBOA particles transported to urban areas.