Air Pollution from Particulate Matter
- What is particulate matter?
- Latest air quality planning that addresses the PM NAAQS
- Related Web pages and publications
- Get more information on the Texas SIP and contact the TCEQ
Particulate matter, or particulates, are anything that is suspended in the air. Particulates are classified by size. Larger or coarse particles range from 2.5 to 10 microns, while fine particles measure 2.5 microns or smaller. Particulates can be caused by natural phenomena or human activity. In high enough concentrations, particulates can aggravate existing respiratory problems or trigger new ones. The TCEQ measures both fine and coarse particulates across the state of Texas.
Inhalable coarse particulate matter, or PM10, is defined as particles with an aerodynamic diameter less than or equal to a nominal 10 microns. PM10 can be found near roadways or dusty areas.
Fine particulate matter, or PM2.5, is defined as particles with an aerodynamic diameter less than or equal to a nominal 2.5 microns. PM2.5 can be emitted directly, or can form when gas emissions react in the atmosphere. The EPA established annual and 24-hour NAAQS for PM2.5 for the first time in 1997 to address data indicating that these small particles, which can penetrate more deeply into the lungs, may pose greater health risks than larger particles.
The Current PM2.5 Levels - Soot, Dust, and Smoke in Your Metro Area Web page shows the highest current hourly PM2.5 average for each metropolitan area where one or more continuous PM2.5 monitoring sites are located.
Last updated: 3/11/2013
2012 Revised Annual PM2.5 NAAQS
On December 14, 2012, the United States Environmental Protection Agency (EPA) promulgated a revised rule for the PM NAAQS. In this rule, the EPA strengthened the primary annual PM2.5 standard from 15.0 micrograms per cubic meter (μg/m3) to 12.0 μg/m3. All other existing primary and secondary standards for both PM2.5 and PM10 were retained.
No counties in Texas are currently designated nonattainment nor are any counties in maintenance status for the primary annual PM2.5 standard.
State designation recommendations to the EPA based on 2010 through 2012 data are due December 13, 2013. The EPA's final designations are expected by December 12, 2014.
For additional information, please visit the EPA's Particulate Matter Regulatory Actions Web page.
Comments on Proposed Disapproval of 2006 PM2.5 Infrastructure Plan
On May 13, 2011, the TCEQ submitted comments regarding the EPA's proposed disapproval of Texas' state implementation plan (SIP) revision addressing infrastructure requirements for the 2006 PM2.5 NAAQS.
On April 13, 2011, the EPA published in the Federal Register a proposed disapproval of Texas' infrastructure submission ("infrastructure SIP") addressing the Federal Clean Air Act, §110(a)(2)(D)(i)(I) transport requirements for the 2006 PM2.5 NAAQS (76 FR 20602). Texas' 2006 PM2.5 infrastructure SIP revision was submitted to the EPA on November 23, 2009.
Recommendation: Designation for Harris County under the 1997 Annual PM2.5 Standard
On October 8, 2009, the EPA sent a letter to the governor concerning violations of the annual PM2.5 standard at the Clinton Drive monitor in Harris County for 2006 through 2008. The EPA’s request was based on 2006 through 2008 ambient air monitoring data that indicated one monitor in Harris County was above the 1997 annual PM2.5 NAAQS of 15 µg/m3. On November 19, 2009, the TCEQ hosted an informational meeting regarding the designation recommendation for Harris County. The meeting provided the public an opportunity for discussion on the recommendation.
On January 20, 2010, the TCEQ sent to the EPA certified, quality-assured 2009 data for the three monitors in Harris County, which all report arithmetic means below 13 µg/m3. On February 5, 2010, the governor recommended to the EPA that all areas in Texas, including Harris County, remain designated in attainment of the 1997 annual PM2.5 standard.
- Recommendation Package:
On April 28, 2010, the EPA sent a letter to the governor of Texas concurring with his recommendation that Harris County remain attainment for the 1997 annual PM2.5 standard based on 2009 design values.
- EPA General Page on Particulate Matter
- NAAQS for Particulate Matter
- TCEQ PM2.5 Data: Soot, Dust, Smoke (Particulate Matter)
- Clean Air Interstate Rule
- List of Texas SIP Revisions