Effective December 29, 2004, the United States Environmental Protection Agency (U.S. EPA) no longer considered t-butyl acetate (TBAC) a Volatile Organic Compound (VOC) for purposes of permit emission limits or for material content requirements. It will, however, continue to require recordkeeping and reporting requirements similar to VOCs. This means that facilities currently tracking their VOC usage will now also be required to track their TBAC emissions as a separate category.

Why did EPA remove TBAC from the category of VOCs?
EPA received a petition from a manufacturer requesting that TBAC not be considered a VOC. EPA reviewed the data and determined that the chemical is considered negligibly reactive, meaning the compound forms less ground-level ozone than ethane. As a result, EPA revised the definition of VOC to exclude TBAC for purposes of emission limits or product formulations. However, since even negligibly reactive compounds may contribute to ozone formation if present in sufficient quantities, EPA wants to continue tracking the usage of TBAC to determine its effects.

TBAC is a chemical that is currently used to make pharmaceutical, pesticides and other products. Since it may be a suitable substitute for more reactive and harmful substances like toluene and xylene, it is estimated that TBAC will soon be found in industrial coatings, adhesives, contact cement, and solvent based inks.

How do I know whether I have TBAC?
Determining whether TBAC is present in the materials used at your facility can be done by checking your Material Safety Data Sheets (MSDS). TBAC, with a CAS # 540-88-5, will be listed as an ingredient. This information is commonly found in the Hazardous Ingredients Section of the MSDS. If it is listed on the MSDS, you can determine how much TBAC is present in a gallon by multiplying the weight percent of the TBAC by the weight per gallon (density) of the material, typically found in the Physical & Chemical Properties Section of the MSDS. The answer from that calculation can then be multiplied by the number of gallons of material used to determine the total TBAC emissions. If multiple materials contain TBAC, do this calculation for each material and add the emissions for the total TBAC emissions from your facility.

What does this mean for air pollution requirements in Wisconsin?
Effective January 1, 2006, Wisconsin Department of Natural Resources (DNR) changed their rules to reflect U.S. EPA's definition of a VOC. Therefore, when determining if an air pollution permit (construction or operation permit) is needed, you do not need to include TBAC in the VOC emissions estimates. When it comes to preparing your annual emissions inventory report for DNR's Consolidated Reporting System (CRS), there is a unique way to determine whether you must report TBAC and exactly what is reported.

When reporting emissions to the CRS, you must include any TBAC emissions together with your total VOCs to determine if you are above the 6,000 pound per year reporting threshold for VOCs. If this total, VOCs plus TBAC, is above 6,000 pounds you must report all of those emissions, but the TBAC emissions should be included separate from VOCs in the report.

For example, if you have 5900 pounds of VOCs and 120 pounds of TBAC, then your total emissions are 6020 pounds. You would then report 5900 pounds VOC and 120 pounds TBAC on the CRS.

If you have any further questions about TBAC emissions, feel free to contact Renee Lesjak Bashel at 608-264-6153.

-- Renee Lesjak Bashel

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Please send comments or questions to Barbro McGinn, editor.