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Ground-level Ozone Pollution

Volatile Organic Compound Exemptions

What are VOCs?

Volatile Organic Compounds (VOC's) react with nitrogen oxides on hot summer days to form ozone (smog). Car exhaust, gasoline-powered lawn and garden equipment, gasoline dispensing stations, industrial coating operations, printing shops, paints, household chemicals - are some of the sources of VOC. There are thousands of individual chemical species of VOCs that can react to form ozone.  The regulatory definition of VOC, including those compounds determined to have neglible photochemical reactivity,  has been pubished in the Code of Federal Regulations Part 51.100.  

What are VOC Exemptions?

Some VOCs react slowly and changes in their emissions have limited effects on local or regional ozone pollution episodes.   Those VOCs, determined to have low photochemical reactivity by approved test methods, may be excluded as VOC for regulatory purposes.  These determinations are made by regulation and are commonly referred to as VOC Exemptions. Note that EPA will only exempt pure compounds.

The policy of excluding negligibly reactive compounds from the regulatory definition of VOC was first laid out in the “Recommended Policy on Control of Volatile Organic Compounds” (42 FR 35314, July 8, 1977) and was supplemented subsequently with the “Interim Guidance on Control of Volatile Organic Compounds in Ozone State Implementation Plans

VOC Exemption Rules

The most recent list of VOC Exemptions are available here.