Particulate Matter 2.5 (PM2.5)
2006 24-Hour Particulate Matter 2.5 (PM2.5)
On November 15, 2013, the U.S. Environmental Protection Agency (EPA) proposed a rule to clarify PM2.5 implementation requirements to the states for current 1997 and 2006 nonattainment areas. In response to a D.C. Circuit Court decision addressing the role subpart 4 of Part D, title 1 of the Clean air Act in implementing the fine particle pollution (PM2.5) air quality standards.
As part of the actions taken by EPA areas that were designated nonattainment for the 1997 and/or 2006 PM2.5 standards were initially designated as “moderate” by operation of law. The deadline for submitting attainment related and nonattainment NSR SIP elements required under subpart 4 was December 31, 2014.
On December 2, 2014 the Imperial County Air Pollution Control District Board of Directors fully approved the "Imperial County 2013 SIP for the 2006 24-hr PM2.5 Moderate Nonattainment Area" plan.
On December 18, 2014 the California Air Resources Board approved the Imperial County 2013 State Implementation Plan for the 2006 24-hour PM2.5 Moderate Nonattainment Area. Final PM2.5 Plan
2012 Annual Particulate Matter 2.5 (PM2.5)
On January 15, 2013, the U.S. Environmental Protection Agency (EPA) finalized its revision to the suite of standards for PM to provide requisite protection of public health and welfare and made corresponding revisions to the data handling conventions for PM and to the ambient air monitoring, reporting and network design requirements.
With regard to the primary (health-based) standards for fine particles (PM2.5) the EPA revised the annual PM2.5 standard by lowering the level to 12.0 micrograms per cubic meter so as to provide increased protection against health effects associated with long- and short-term exposures.
In addition, the EPA designated the previously determined Non-attainment area in Imperial County as a "Moderate" non-attainment area for the 2012 Annual PM2.5 primary standard.
On August 24, 2016 the EPA finalized its implementing rule for the newly established primary annual standard for PM2.5. Moderate non-attainment areas are required by Code of Federal Regulations section 51.1003(a) to submit a State Implementation Plan no later than 18 months from the date of designation (October 2016).
On April 24, 2018 the Imperial County Air Pollution Control District Board of Directors fully approved the "Imperial County 2018 Annual Particulate Matter Less than 2.5 Microns in Diameter State Implementation Plan"
On May 25, 2018 the California Air Resources Board approved the Imperial County 2018 Annual Particulate Matter Less than 2.5 Microns in Diameter State Implementation Plan Final Annual PM2.5 Plan