On this page:

• Rule Summary
• Rule History
• Additional Resources

Rule Summary

In 2012, based on EPA’s review of the air quality criteria and the national ambient air quality standards (NAAQS) for particulate matter (PM), the EPA revised the annual PM_2.5 standards, and made related revisions in:

• data handling conventions
• the Air Quality Index (AQI)
• the ambient air monitoring, reporting and network design requirements
• regulations for the prevention of significant deterioration (PSD) program

The EPA retained the existing primary (health-based) and secondary (welfare-based) 24-hour standards for PM_2.5 and PM₁₀, without revision.

Rule History

08/11/2016 - Technical Correction to Equation 2 in Appendix N:  Direct Final Rule and Parallel Proposal

01/15/2013 – Final Rule

06/29/2012 – Proposed Rule & Correction

Additional Resources

Fact Sheet Technical Correction to Equation 2 in Appendix N:  Final Rule

Fact Sheet Technical Correction to Equation 2 in Appendix N:  Direct Final Rule and Parallel Proposal

Regulatory Impact Analysis for the Final Revisions to the National Ambient Air Quality Standards for Particulate Matter

Fact Sheets and Additional information Regarding the 2012 Revision to the Particulate Matter (PM_2.5) National Ambient Air Quality Standards (NAAQS)

Scientific and Technical Documents Supporting the 2012 Review of the PM Standards

Related Rules

Implementation of the National Ambient Air Quality Standards (NAAQS) for Fine Particulate Matter (PM_2.5): State Implementation Plan (SIP) Requirements

2006 National Ambient Air Quality Standards (NAAQS) for Particulate Matter (PM_2.5)