in Mississippi

Particulate Matter
Particulate matter includes emissions from all types of combustion, including motor vehicles,
power plants, agricultural burning, and some industrial processes. The EPA regulates only
particulate matter with a diameter of 10 microns or less, known as PM10. Particulate matter
comes from a wide variety of stationary, mobile, and natural sources.
In 1997, EPA set primary and secondary ambient air quality standards for fine particulate matter
(PM2.5). The primary and secondary standards were set at an annual average of 15 µg/m3 and a
24-hour average of 65 µg/m3.
In 2006, the EPA lowered the 24-hour average primary/secondary standards from 65 µg/m3 to 35
µg/m3. The annual average standard remained at 15 µg/m3. (40 C.F.R. § 50.13)
Monitoring Ozone and Air Quality in Mississippi
MDEQ monitors eight (8) locations in eight (8) counties in Mississippi, focusing on the
population centers of Jackson, Tupelo, the Gulf Coast, and DeSoto County. The (8) locations
include: Adams, Bolivar, DeSoto, Harrison, Hinds, Jackson, Lauderdale, and Lee counties. In
2004, the EPA designated all counties as “attainment,” based on 2001-2003 air monitoring data.
The EPA has recently revised standards for ground-level ozone. These revisions present new
challenges for the state so that the EPA will continue to designate all counties as attainment.
A “nonattainment” designation would not directly impact economic development, but there can
be indirect consequences due to the designation. For example, industrial facilities could be
required to install pollution control equipment, take limits on their production, or otherwise find
reductions in emissions by “offsetting” in order to expand. In addition, new facilities wanting to
locate in a nonattainment area will most likely be required to install pollution controls or take
stringent operational limits.
The 1990 Clean Air Act Amendments (CAAA) requires that, in areas experiencing air quality
problems, transportation planning must be consistent with air quality goals. This is determined
through the transportation conformity process. Transportation conformity is a way to ensure that
Federal funding and approval goes to those transportation activities that are consistent with air
quality goals. Conformity applies to transportation plans, transportation improvement programs
(TIPs), and projects funded or approved by the Federal Highway Administration (FHWA) or the
Federal Transit Administration (FTA) in areas that do not meet or previously have not met air
quality standards for ozone, carbon monoxide, particulate matter, or NO 2 . The EPA labels these
areas as "nonattainment areas.”
Section 176 of the CAAA defines conformity to a SIP to mean conformity to the plan’s purpose
of eliminating or reducing the severity and number of violations of the NAAQS and achieving
expeditious attainment of the standards. Designated Metropolitan Planning Organizations are
required to perform conformity determinations by ozone nonattainment area for their
Transportation Plans and TIPs.
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