Requests for Redesignation and Maintenance Plans

States maintain state implementation plans (SIPs) describing how they will implement, maintain, and enforce the National Ambient Air Quality Standards (NAAQS) for six common “criteria” pollutants, which include carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO₂), ozone (O₃), particulate matter (PM), and sulfur dioxide (SO₂). Requests for redesignation are documents that IDEM submits to United States Environmental Protection Agency (U.S. EPA) requesting a change in the status of an area’s air quality designation under a NAAQS from “nonattainment” (not meeting) to “attainment” (meeting). When data from air quality monitors and/or models show that a nonattainment area has achieved the NAAQS, Indiana will petition, or request, that U.S. EPA grant the area's “redesignation.” Indiana may submit a request for redesignation to U.S. EPA when the following, specific criteria have been met:

• The area has monitored attainment of the NAAQS, based on three consecutive years of ambient air quality monitoring data,
• The area has a fully approved SIP,
• U.S. EPA has determined that the improvement in air quality is due to permanent and enforceable reductions in emissions,
• Indiana has submitted, and U.S. EPA has approved, a maintenance plan for the area, and
• The area has met all other applicable federal CAA requirements.

Maintenance Plans

An area that is redesignated to attainment must demonstrate continued attainment of the NAAQS. Maintenance plans are documents describing how a “nonattainment” area that has met the NAAQS will continue to maintain the level of air quality it has achieved. A maintenance plan contains measures showing how air quality will be maintained, considering projected growth, for a period of ten years. If outdoor air monitors show the area does not meet the standard, the maintenance plan must include a commitment to determine appropriate measures to address the cause of the problem. Generally, the control measures used to improve air quality will remain in place. “Maintenance area” is a common term for areas that have been redesignated to attainment status.

IDEM has submitted Requests for Redesignation and Maintenance Plans for the following areas/counties and standards:

• Allen County:
  • 1997 8-Hour Ozone Standard
• Central Indiana:
  • 1997 8-Hour Ozone Standard (Boone, Hamilton, Hancock, Hendricks, Johnson, Madison, Marion, Morgan, and Shelby Counties)
  • 1997 Annual Fine Particles (PM_2.5) Standard (Hamilton, Hendricks, Johnson, Marion, and Morgan Counties)
• Clark, Floyd, and Jefferson Counties:
  • 2015 8-Hour Ozone Standard (Clark and Floyd Counties)
  • 1997 8-Hour Ozone Standard (Clark and Floyd Counties)
  • 1997 Annual Fine Particles (PM_2.5) Standard (Clark and Floyd Counties, and Madison Township within Jefferson County)
• Daviess and Pike Counties:
  • 2010 Primary 1-Hour Sulfur Dioxide Standard (Veale Township in Daviess County, Washington Township in Pike County)
• Dearborn County:
  • 2008 8-Hour Ozone Standard (Lawrenceburg Township)
  • 1997 8-Hour Ozone Standard (Lawrenceburg Township)
  • 1997 Annual Fine Particles (PM_2.5) Standard (Lawrenceburg Township)
• Delaware County:
  • 1997 8-Hour Ozone Standard
  • 2008 Annual Lead Standard (Area within Muncie)
• Evansville, Indiana Area:
  • 1997 8-Hour Ozone Standard (Vanderburgh and Warrick Counties)
  • 1997 Annual Fine Particles (PM_2.5) Standard (Dubois, Vanderburgh, and Warrick Counties, Montgomery Township in Gibson County, Ohio Township in Spencer County, and Washington Township in Pike County)
• Greene County:
  • 1997 8-Hour Ozone Standard
• Huntington County:
  • 2010 Primary 1-Hour Sulfur Dioxide Standard (Huntington, IN area, made up of Huntington Township in Huntington County)
• Jackson County:
  • 1997 8-Hour Ozone Standard
• Lake County:
  • 1971 8-Hour Carbon Monoxide Standard (Area within East Chicago)
  • 1971 Sulfur Dioxide Standard
• Lake and Porter Counties:
  • 2008 8-Hour Ozone Standard
  • 1997 8-Hour Ozone Standard
  • 1997 Annual Fine Particles (PM_2.5) Standard
• LaPorte County:
  • 1997 8-Hour Ozone Standard
• Marion County:
  • 1971 8-Hour Carbon Monoxide Standard (Area within Downtown Indianapolis)
  • 1978 Annual Lead Standard (Areas within Franklin and Wayne Townships)
  • 2010 Primary 1-Hour Sulfur Dioxide Standard (Center, Perry, and Wayne Townships)
• Morgan County:
  • 2010 Primary 1-Hour Sulfur Dioxide Standard (Clay and Washington Townships)
• St. Joseph and Elkhart Counties:
  • 1997 8-Hour Ozone Standard
• Vigo County:
  • 1997 8-Hour Ozone Standard
  • 2010 Primary 1-Hour Sulfur Dioxide Standard (Fayette and Harrison Townships in Terre Haute)

Redesignation and Maintenance Plans can also be browsed by criteria pollutant.

IDEM’s Nonattainment Status for Indiana Counties page provides charts with the status of all areas/counties, including dates of approved redesignations, under previous and current standards for all criteria pollutants.