Section 52.785 - Control strategy: Carbon monoxide(a) The requirements of subpart G of this chapter are not met because the plan does not provide for attainment and maintenance of the national standards for carbon monoxide in the Metropolitan Indianapolis Intrastate Region by May 31, 1975.(b) On December 21, 1999, the Indiana Department of Environmental Management submitted carbon monoxide maintenance plans for those portions of Lake and Marion Counties which they requested the Environmental Protection Agency redesignate to attainment of the carbon monoxide national ambient air quality standard.(c) Approval-The Indiana Department of Environmental Management (IDEM) submitted Carbon Monoxide (CO) Limited Maintenance Plan Updates for Lake and Marion Counties on January 12, 2009. The updated Limited Maintenance Plans demonstrate attainment of the CO National Ambient Air Quality Standard (NAAQS) for Lake and Marion Counties for an additional ten years.38 FR 16565, June 22, 1973, as amended at 51 FR 40676, Nov. 7, 1986; 65 FR 2888 , Jan. 19, 2000; 74 FR 52893 , Oct. 15, 2009