Updated October 23, 2007
Particulate matter or particulates are defined as anything that
is suspended in the air. Particulates are classified by their size.
Larger or coarse particles range in size from 2.5 to 10 microns in
size, while fine particles are smaller than 2.5 microns in size.
Particulates are too small to be seen with the naked eye.
Particulates can be caused by natural phenomena or come from
man-made sources. 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.
PM2.5 Designation
Recommendation Introduction
On December 18, 2006, the EPA revised the 24-hour PM 2.5
National Ambient Air Quality Standard (NAAQS) for fine particulate
matter of 2.5 microns and less (PM 2.5) from 65 micrograms per
cubic meter (µg/m3) to 35µg/m3.
Section 107(d)(1)(A) of the Federal Clean Air Act (FCAA) requires
the governor of each state to submit to the EPA a recommendation
regarding attainment, nonattainment, or unclassifiable statistical
areas according to the new or revised standard. The deadline for
submitting recommended designations under the revised 24-hour PM
2.5 standard to the EPA is December 18, 2007. The EPA recommends
that states identify violating areas using the most recent three
years of air quality data, preferably calendar years 2004 through
2006, stored in the EPA Air Quality System (AQS). The PM 2.5
violations are identified using data from the Federal Reference
Method and the Federal Equivalent Method monitors that are sited
and operated in accordance with 40 Code of Federal Regulations
(CFR) Part 58. Based on 2004 through 2006 monitoring data from EPA
AQS, no monitors in Texas are violating the new PM 2.5 24-hour
standard.
Commission's
Approval
On October 12, 2007, the commission approved submitting the
recommendation that Texas be designated attainment for the revised
24-hour PM 2.5 NAAQS to the governor for his consideration.
Supporting
Data
The review and quality assurance of the 2004 through 2006
monitoring data is complete and information is shown in the
designation recommendation table. One special-purpose
microscale monitor in El Paso, the Sun Metro site, has measured PM
2.5 levels higher than the 24-hour standard. In 2000, the agency
established Sun Metro as a microscale site with a continuous PM 2.5
monitor and a supplemental speciation sampler to analyze the impact
of transborder transport into Texas across the Rio Grande River.
However, the EPA has not included these data in the AQS at this
time because the monitor is a microscale monitor. The attached
table explains that the EPA has not previously included Sun Metro
as a monitor to be considered for the purposes of designation,
hence the commission recommends excluding the Sun Metro site from
the nonattainment designation recommendation. All monitors in Texas
with data eligible for comparison to the 24-hour PM2.5 standard
meet the revised standard.
Documents
The PM 2.5 designation recommendation documents are in PDF
format (help with PDF).
Contact
For additional information about the SIP, please direct your
inquiries to:
Ita Ufot
TCEQ, Air Quality Planning Section
Phone: (512) 239-1935
