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Particulate Matter (PM)

Fact Sheet: 1997 PM 2.5 NAAQS Determinations of Attainment (Clean Data Determinations)


  • On November 10 and November 18, EPA determined that five fine particulate matter (PM2.5) nonattainment areas currently have air quality that attains the level of the 1997 PM2.5 national ambient air quality standard (NAAQS.)  This determination, known as a Clean Data Determination, suspends the obligation to meet certain Clean Air Act requirements provided the area continues to meet the NAAQS. 
  • The Clean Data Determination suspends the obligation to submit the following state implementation plan (SIP) elements: attainment demonstration, reasonably available control measures/reasonably available control technology, contingency measures, and reasonable further progress. 
  • EPA previously published proposed determinations that the areas of Chicago-Gary-Lake County, IL-IN; Evansville, IN;  Parkersburg-Marietta, WV-OH,  Wheeling, WV-OH; and Martinsburg-Hagerstown, WV-MD are in attainment of the 1997 PM2.5 NAAQS.   However, EPA had not previously made final formal determinations that these areas are attaining the NAAQS. 
  • Following notice and comment rulemaking, EPA is making a final Clean Data Determination for each of these areas. The EPA approved final actions are available online at the following sites:
  • These rulemakings will be published soon in the Federal Register.


  • The applicable statutory and regulatory requirements for nonattainment SIPs for the 1997 PM2.5 NAAQS are provided in the PM2.5 Implementation Rule available at http://www.epa.gov/pm/actions.html

Attainment demonstration

  • States with nonattainment areas are required to analyze the potential of those areas to meet the 1997 PM2.5 standard.  The state uses air quality models and other relevant technical information to demonstrate its ability to achieve the air quality standard by a certain date.
  • (Note: for an area with a more severe or complex nonattainment problem, the state could propose in its plan to extend the attainment date an additional 1 to 5 years beyond the initial five year period if it meets the statutory and regulatory requirements.) 
  • This SIP element was due to EPA in April 2008.

Reasonably Available Control Measures/Reasonably Available Control Technology

  • Each nonattainment SIP must include RACM and RACT as necessary for the area to attain the 1997 PM2.5 NAAQS.  The Clean Air Act requires the state to demonstrate that it has adopted all reasonably available control measures, considering economic and technical feasibility and other factors that are needed to show the area will attain the fine particle standards as expeditiously as practicable. 
  • The attainment demonstration takes into account projected emission reductions from existing federal and state measures, plus any additional RACM/RACT that can be adopted by the state to attain “as expeditiously as practicable.”  Air quality modeling of these projected emissions reductions in future years is an important element of the attainment demonstration.
  • This SIP element was due to EPA in April 2008.

Reasonable Further Progress

  • SIPs must also provide for steady progress, also known as RFP, toward attainment of the 1997 PM2.5 standard.  This provides a way to ensure states make continual progress toward meeting the standard by their attainment date.
  • The PM2.5 Implementation Rule provides that for areas with an attainment date within 5 years of designation, the attainment demonstration is considered to satisfy the RFP requirement.  Areas with attainment dates beyond 2010 are required to submit an RFP plan according to the requirements in the implementation rule. 
  • This SIP element was due to EPA in April 2008.

Contingency Measures

  • SIPs must also include contingency measures, which are emission reduction measures to be undertaken if the area fails to satisfy the RFP requirement or fails to attain the standards by the attainment date.  These measures are to take effect without significant further action by the state or EPA.
  • This SIP element was due to EPA in April 2008

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