The U.S. Environmental Protection Agency (EPA) has issued a final rule that would add HFO-1234YF to the list of substances excluded from the regulatory definition of volatile organic compounds (VOC), the Automotive Aftermarket Industry Association reported.

The agency made this decision based on 1234yf’s “negligible contribution to tropospheric ozone formation.” Tropospheric ozone is commonly known as smog and is formed when VOCs and nitrogen oxides react in the atmosphere in the presence of sunlight. EPA and many states limit use of VOCs in products in order to minimize smog formation, AAIA noted.

1234YF was developed as a substitute refrigerant in motor vehicles for HFC-134a due to its very low global warming potential (GWP) of four. By comparison, 134a has a GWP of 1430. Honeywell had submitted a petition to EPA in 2009 requesting that it be exempt 1234yf from the regulatory definition of VOC.

The EPA notice points out that the action to exclude 1234yf from the VOC definition may also affect whether 1234yf is considered a VOC for state regulatory purposes depending on whether a state relies on the agency’s definition of VOCs, AAIA noted. EPA further states that, “states are not obligated to exclude from control as VOCs those compounds that the EPA has found to be negligibly reactive. However, states may not take credit for controlling these compounds in their ozone control strategies.”

The EPA final rule can be found at: http://www.gpo.gov/fdsys/pkg/FR-2013-10-22/pdf/2013-23783.pdf.