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Reactive Organic Carbon Emissions from Volatile Chemical Products
Citation:
Seltzer, K., E. Pennington, V. Rao, B. Murphy, M. Strum, K. Isaacs, AND H. Pye. Reactive Organic Carbon Emissions from Volatile Chemical Products. CMAS Conference, Chapel Hill, NORTH CAROLINA, October 26 - 30, 2020.
Impact/Purpose:
Volatile chemical products (VCPs) are a source of volatile organic compounds (VOCs) to the atmosphere leading to formation of ozone and PM2.5. Accurate methods of estimating VCP emissions are needed to understand their role in air quality and to provide robust methods for the National Emissions Inventory (NEI). This work demonstrates a bottom-up framework for estimating emissions that will serve as the foundation for VCPs in the 2020 NEI.
Description:
Volatile chemical products (VCPs) are an increasingly important source of anthropogenic reactive organic carbon (ROC) emissions. Among these sources are everyday items, such as personal care products, general cleaners, architectural coatings, pesticides, adhesives, and printing inks. These emissions have long been accounted for in the US EPA’s National Emission Inventory (NEI) as the solvent sector, but new inventory methods have suggested the NEI could be biased low by factors of 2-3. As the influence of VCPs on secondarily formed pollutants grows in relevance, the need to resolve these differences becomes increasingly important. Here, we develop VCPy, a new framework to model ROC emissions from VCPs throughout the United States, with additional applications to spatially allocate these emissions to regional and local scales. In this framework, fate and transport assumptions are a function of the use timescale for product-use categories and the evaporation timescales of individual compounds within these categories, which are a function of their physiochemical properties. Since ingredients in these product categories are considered individually, determination of speciated emission profiles is explicit. This approach also enables quantification of emission volatility distributions and the abundance of different compound classes. Overall, we find National-level emissions of ROC from VCPy to be consistent with the NEI, but State and County-level estimates can differ substantially. In addition, we test the sensitivity of predicted emission factors to uncertain parameters, such as use and evaporation timescales, through Monte Carlo analysis, evaluate the inventory using published emission ratios, and map emissions to common chemical mechanisms for ease of research use in the chemical transport modelling community.
