Comprehensive environmental impact assessment of exempt volatile organic compounds in California

Regulatory agencies control emissions of volatile organic compounds (VOCs) because they react with nitrogen oxides in the presence of sunlight to yield tropospheric or ground-level ozone. However, reaction rates vary widely depending upon the type of VOC. Most VOC regulations developed in the United States consist of mass-based limits, except that VOCs found to be minimally reactive are exempted from regulations. However, the granting of VOC exemptions may lead to greater emissions of the VOCs so exempted. In this paper, we establish and describe a comprehensive approach that assesses several impacts of these greater emissions for VOCs proposed for exemption due to their negligible contribution to tropospheric ozone formation. These impacts include changes to tropospheric ozone, secondary organic aerosol, stratospheric ozone depletion, climate, other media (water and soil), indoor exposure, health, and the economy. This approach was applied to several VOCs: tertiary-butyl acetate (t-BAc), methyl formate, and nine fluorinated organic compounds, and the results are presented here. It is concluded that this comprehensive approach should be considered by regulatory agencies when exempting a VOC.

► We develop a comprehensive environmental impact approach for exempt volatile organic compounds.
► These impacts include changes to atmosphere, multimedia, health, and economy.
► Case studies are presented for t-butyl acetate, methyl formate, and nine fluorinated compounds.
► This approach should be considered by regulatory agencies when exempting a chemical.