1998 Revisions to the Carbon Monoxide Maintenance Plan Categories Topics Air Quality Plans Programs California State Implementation Plans Type Information On October 22, 1998, CARB revised the SIP to incorporate the effects of the recent CARB action to remove the wintertime oxygen requirement for gasoline in certain areas.CARB DocumentsNotice of Public Hearing1998 Plan (October 6, 1998) Related Resources 2023 San Joaquin Valley PM2.5 Plan 2023 Mariposa County Ozone Attainment Plan 2023 Mariposa County Reasonably Available Control Technology SIP