Research Program Area: Atmospheric Processes
Topic Areas: Modeling
Low vapor pressure-volatile organic compounds (LVP-VOCs) are exempt from the VOC content limits for consumer products and are defined in the California Code of Regulations. To evaluate the availability of LVP-VOCs that may contribute towards ozone formation from the use of consumer products, this report describes the development of modeling tools for two potential modes of releases during the use of consumer products (i.e., direct release to the outdoor air and disposed down the drain). For the fate of LVP-VOCs found in some consumer products used in down-the-drain applications (e.g., laundry detergents, fabric softeners, dishwashing detergents, and other laundry products), we applied a wastewater treatment plant (WWTP) fate model to predict the fraction of LVP-VOCs that may volatilize at WWTPs. For the portion of the LVP-VOCs volatilized to air during product use, we applied a multi-compartment mass-balance model to track the fate of LVP-VOCs in a multimedia urban environment. Based on the modeling results for the selected 33 LVP-VOCs, loss by volatilization in a WWTP is negligible for most compounds, suggesting that a majority of the LVP-VOCs will not be available for ozone formation reactions in the atmosphere once they are disposed down the drain. In contrast, for the LVP-VOCs in a consumer product that is volatilized to air and is assumed to be in the gas phase, greater than 90% will remain in the air and may participate in photochemical reactions either at the source location or in the downwind areas. Comparing results from these two modes of releases emphasizes the importance of determining the fraction of LVP-VOCs volatilized versus the fraction disposed down the drain when a product is used by consumers. The results from this study can provide important information and modeling tools to evaluate the impact of LVP-VOCs on air quality.
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
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