Air Plan Approval; Illinois; Volatile Organic Material Definition Update

The Environmental Protection Agency (EPA) is approving a revision to the Illinois State Implementation Plan (SIP). The revision is amending the Illinois Administrative Code (IAC) by updating the definition of volatile organic material (VOM) and volatile organic compounds (VOC) to exclude (Z) -1,1,1,4,4,4-hexafluorobut-2-ene. This revision is consistent with an EPA rulemaking in 2018, which exempted this compound from the Federal definition of VOC on the basis that the compound makes a negligible contribution to tropospheric ozone formation. EPA proposed to approve this action on February 11, 2021 and received no adverse comments.