EPA revised the regulatory definition of volatile organic compounds (VOCs) under the CAA, adding trans-1,1,1,4,4,4-hexafluorobut-2-ene to the list of compounds excluded from the regulatory definition of VOCs on the basis that the compound makes a negligible contribution to tropospheric ozone formation.

NMFS announced final revisions to the Process for Distinguishing Serious From Non-Serious Injury of Marine Mammals.

NMFS finalized revisions to the Guidelines for Preparing Stock Assessment Reports Pursuant to the Marine Mammal Protection Act.

FWS announced the availability of and seeks comment on revised draft marine mammal stock assessment reports for the Pacific walrus and for each of the three northern sea otter stocks in Alaska in accordance with the Marine Mammal Protection Act.

SIP Proposal: North Carolina (replacing previously approved memoranda of agreement (MOAs) with 13 updated MOAs outlining transportation conformity criteria and procedures related to interagency consultation, conflict resolution, public participation, and enforceability of certain transportation-related control and mitigation measures).

SIP Approval: Arizona (revisions concerning nitrogen oxide and particulate matter emissions from combustion equipment and internal combustion engines in the Maricopa County Air Quality Department).

SIP Approval: Tennessee (revisions regarding the installation, maintenance, and termination of ambient air sulfur dioxide (SO2) monitors near large industrial SO2 emitting sources).

SIP Approval: Georgia (1997 eight-hour ozone NAAQS limited maintenance plan for the portion of Murray County, Georgia, previously designated nonattainment).

SIP Approval: California (revisions concerning the issuance of permits for stationary sources, focusing on the preconstruction review and permitting of major sources and major modifications, for the Tuolumne County Air Pollution Control District). 

SIP Approval: Georgia (1997 eight-hour ozone NAAQS limited maintenance plan for the Atlanta, Georgia area).