DEEP: PM2.5 Planning Efforts: Attainment Designations

PM2.5 Planning Efforts

The United States Environmental Protection Agency (EPA) initially promulgated National Ambient Air Quality Standards (NAAQS) for particulate matter less than 2.5 microns in diameter (PM2.5) on July 16, 1997, establishing separate standards for annual and 24-hour averaging periods.  Pursuant to Clean Air Act (CAA) sections 108 and 109, EPA subsequently promulgated a revised 24-hour NAAQS on September 21, 2006 and a revised annual NAAQS on December 14, 2012 based on reviews of health studies showing adverse impacts at concentration levels lower than the 1997 NAAQS.  The annual average NAAQS for PM2.5 is currently 12 µg/m3(micrograms per cubic meter) and the 24-hour average NAAQS is 35 µg/m3.
The State of Connecticut Department of Energy and Environmental Protection (DEEP) began ambient air monitoring for PM2.5 in 1999.  Based on monitored air quality in Connecticut, New York and New Jersey, EPA established initial PM2.5 nonattainment areas effective April 5, 2005 that included Fairfield and New Haven Counties as part of a multi-state nonattainment area for the 1997 annual PM2.5 standard.  This nonattainment area was comprised of the 22 New York, New Jersey and Connecticut counties surrounding New York City.  EPA's rulemaking also declared that the remaining six counties in Connecticut were in attainment for the 1997 NAAQS.  EPA’s nonattainment designations for the 2006 revision to the 24-hour NAAQS took effect on December 14, 2009.  EPA established nonattainment area boundaries for the 2006 24-hour PM2.5 NAAQS identical to those used for the 1997 annual PM2.5 NAAQS.

PM2.5 levels in our air have greatly declined over the last 15 years as successful federal and state emission control programs implemented in Connecticut and other states have reduced levels of this pollutant in the air we breathe.  Monitoring data show that the NY-NJ-CT multi-state area has achieved compliance with both the 1997 annual and 2006 24-hour PM2.5 NAAQS since 2009.  On November 15, 2010, EPA published a formal determination that the NY-NJ-CT multi-state area had achieved measured attainment of the 1997 annual PM2.5 NAAQS.  EPA published a similar finding for the 2006 24-hour PM2.5 NAAQS on December 31, 2012.  DEEP monitoring data also indicate that Connecticut complies with the 2012 annual NAAQS.

On June 22, 2012, DEEP formally submitted to the EPA, the final PM2.5 redesignation request and maintenance plan State Implementation Plan (SIP) for Connecticut's portion of the NY-NJ-CT PM2.5 nonattainment area.  The plan demonstrated that Connecticut’s air quality met both the 1997 annual and the 2006 24-hour PM2.5 NAAQS due to a combination of national, regional and local control measures implemented to reduce emissions and presented a maintenance plan that ensures continued attainment through the year 2025.  On September 24, 2013, EPA published its approval of the PM2.5 redesignation request, establishing October 24, 2013 as the effective date of redesignation to attainment for Connecticut’s portion of the NY-NJ-CT area for both the 1997 annual and 2006 24-hour PM2.5 NAAQS.

By December 14th, 2013, states were required to make recommendations for areas to be designated for attainment or nonattainment for the revised, 2012 annual NAAQS. On December 13, 2013, DEEP submitted to EPA a recommendation for attainment status for the entire State of Connecticut for the 2012 NAAQS.   EPA agreed and designated the state as attainment/unclassifiable (80 FR 2206); this action was effective April 15, 2015.

Links to relevant documents and correspondence are provided below, in reverse chronological order.


NYDEC submitted comments in October 2004 to EPA concerning the designation process, including several that relate to Connecticut's recommendations to EPA:

In August 2004, CTDEP responded to EPA's draft recommendations regarding attainment designations.  EPA acknowledged receipt of CTDEP's response in a September 28, 2004 letter:

EPA indicated its intent to modify the CTDEP's original recommendations in a response dated June 29, 2004:

Connecticut's original recommendation for a statewide attainment designation, along with supporting documents, was provided to EPA in February 2004:

Content Last Updated on March 19, 2018