Fact Sheet — Final Area Designations for the 1-Hour Primary National Ambient Air Quality
Standard for Sulfur Dioxide Established in 2010 (Round 3)
ACTIONS
•	On December 21, 2017, the U.S. Environmental Protection Agency (EPA) took an
additional step to implement the health-based national air quality standard for sulfur
dioxide (SO2) set in 2010. EPA has identified or "designated" areas:
o "nonattainment" - not meeting the 1-hour health based national air quality
standard for SO2 (six areas in three states and two territories),
o "unclassifiable" - not enough information to make a determination (23 areas in
ten states), or
o "attainment/unclassifiable" - meeting the standard and not contributing to a
violation of the standard (all remaining areas except where additional SO2 air
quality monitoring is underway).
The table at the end of this fact sheet provides further details for each area.
•	On June 3, 2010, the EPA strengthened the health-based or "primary" standard for SO2
by establishing a 1-hour standard at a level of 75 parts per billion. On July 25, 2013, the
EPA designated 29 areas in 16 states as nonattainment, but did not at that time
designate other areas (Round 1). A March 2, 2015, court-ordered schedule, required the
agency to complete the remaining SO2 designations by three specific deadlines: July 2,
2016 (completed), December 31, 2017 (Round 3), and December 31, 2020 (Round 4).
•	To meet the December 2017 deadline, EPA has designated areas "nonattainment,"
"unclassifiable," or "attainment/unclassifiable" after evaluating:
o air quality modeling and monitoring data used to characterize SO2 air quality;
o emissions limits established to control sources of SO2; and
o areas not subject to EPA's SO2 Data Requirements Rule.
•	These final designations will take effect 90 days after the notice is published in the
Federal Register.
•	All remaining areas will be designated by December 31, 2020. For these areas, states
chose to install and operate new monitors. The monitors will allow them to generate
three full calendar years of data to inform the designation.
REQUIREMENTS FOR DESIGNATED AREAS
Nonattainment Areas
•	The Clean Air Act requires air agencies to take steps to control pollution in SO2
nonattainment areas. Those steps may include stricter controls on industrial facilities.

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•	State and local governments detail these steps in plans that demonstrate how they will
meet the SO2 standard. Those plans are known as state implementation plans (SIPs).
States have 18 months after the effective date of final designations to develop and
submit their plans to EPA.
•	Once designated, nonattainment areas are subject to Nonattainment New Source
Review requirements. New Source Review is a permitting program for industrial
facilities to ensure that new and modified sources of pollution do not impede progress
toward cleaner air.
•	Nonattainment areas are required to meet the standard as quickly as possible, but no
later than five years after the effective date of final designation. Six months after that
date, EPA must determine whether the area has attained the standard. If EPA
determines that an area has failed to meet the standard, the state has 12 months to
submit a SIP revision that demonstrates that the area will attain the standard within five
years of EPA's determination.
Attainment/Unclassifiable Areas
•	For attainment areas that have sources covered by the Data Requirements Rule, states
must periodically provide EPA with updates on the air quality in those area. Where
states choose to use SO2 monitors, the data are reported to EPA's Air Quality System
(AQS) annually, with a May 1 certification deadline for the prior year's air quality
readings. Where states have chosen to assess air quality using modeling, the rule
requires annual emissions reports to be submitted to EPA by July 1 of each year, and
must include the state's assessment of whether emissions have changed in a manner
that would warrant a new modeling assessment.
BACKGROUND
•	The Clean Air Act requires EPA to issue designations after the agency sets a new
National Ambient Air Quality Standard or revises an existing standard. Areas not
meeting the standard are designated "nonattainment."
•	In June 2010, EPA set a 1-hour, health-based national air quality standard for SO2 at 75
parts per billion. The revised standard will improve public health protection, especially
for children, the elderly and people with asthma. These groups are susceptible to health
problems, including narrowing of the airways which can cause difficulty breathing and
increased asthma symptoms, associated with breathing SO2.

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Round 1:
• In July 2013, after reviewing input from the states, EPA designated 29 areas in 16 states
as nonattainment for the 2010 S02 standard.
Round 2:
• On June, 30, 2016, and November 29, 2016, EPA designated 65 areas in 24 states as:
o "attainment/unclassifiable" - meeting the 1-hour health based national air quality
standard for sulfur dioxide (41 areas),
o "nonattainment" - not meeting the standard (7 areas), or
o "unclassifiable" - not enough information to make a determination (17 areas).
FOR MORE INFORMATION
• For more information on the designation process for the SO2 standard go to EPA's Web
site at http://www.epa.eov/sulfur-dioxide-desienations.

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Round 3 Area Designations - Completed December 2017
State
Area Name
Counties
(p) = partial county
EPA Final Designation
Alabama*
Escambia
County
Escambia
Unclassifiable
Mobile County
Mobile
Unclassifiable
Morgan County
Morgan
Unclassifiable
Pike County,
Pike
Unclassifiable
Shelby County,
AL
Shelby (p)
Unclassifiable
Washington
County
Washington
Unclassifiable

Rest of State
Attainment/Unclassifiable
Alaska

Entire State
Attainment/Unclassifiable
American Samoa

Entire Territory
Attainment/Unclassifiable
Arizona
Coconino
County(p)
Coconino (p)
Navajo Nation
Unclassifiable

Lands of the
Navajo Nation (p)
Attainment/Unclassifiable

Rest of State
Attainment/Unclassifiable
Arkansas

Rest of State
Attainment/Unclassifiable
California

Entire State
Attainment/Unclassifiable
Colorado

Rest of State
Attainment/Unclassifiable

Southern Ute
Indian Reservation
Attainment/Unclassifiable
Commonwealth
of the Northern
Marianas Islands

Entire Territory
Attainment/Unclassifiable
Connecticut

Entire State
Attainment/Unclassifiable
Delaware

Entire State
Attainment/Unclassifiable
District of
Columbia

Entire District
Attainment/Unclassifiable
Florida
Citrus County,
FL
Citrus (p)
Unclassifiable
Hillsborough-
Polk County, FL
Hillsborough (p)
Polk (p)
Nonattainment
Mulberry, FL
Area
Hillsborough (p)
Polk (p)
Unclassifiable

Rest of State
Attainment/Unclassifiable
Georgia*

Rest of State
Attainment/Unclassifiable
Guam
Piti-Cabras
Piti-Cabras
Nonattainment

Rest of Territory
Attainment/Unclassifiable
Hawaii*

Kalawao County
Attainment/Unclassifiable

Kauai County
Attainment/Unclassifiable

Maui County
Attainment/Unclassifiable
Idaho

Entire State
Attainment/Unclassifiable

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State
Area Name
Counties
(p) = partial county
EPA Final Designation
Illinois*

Rest of State
Attainment/Unclassifiable
Indiana*
Huntington, IN
Huntington (p)
Nonattainment

Rest of State
Attainment/Unclassifiable
Iowa
Linn County, IA
Linn
Unclassifiable

Rest of State
Attainment/Unclassifiable
Kansas

Rest of State
Attainment/Unclassifiable
Kentucky*

Rest of State
Attainment/Unclassifiable
Louisiana*
Evangeline
Parish, LA
Evangeline Parish
(P)
Nonattainment
St. Mary Parish
St. Mary
Unclassifiable


Rest of State
Attainment/Unclassifiable
Maine

Entire State
Attainment/Unclassifiable
Maryland*

Rest of State
Attainment/Unclassifiable
Massachusetts

Entire State
Attainment/Unclassifiable
Michigan

Rest of State
Attainment/Unclassifiable
Minnesota
Goodhue
County
Goodhue
Unclassifiable

Rest of State
Attainment/Unclassifiable
Mississippi

Rest of State
Attainment/Unclassifiable
Missouri*

Rest of State
Attainment/Unclassifiable
Montana

Rest of State
Attainment/Unclassifiable
Nebraska*

Rest of State
Attainment/Unclassifiable
Nevada

Entire State
Attainment/Unclassifiable
New Hampshire

Rest of State
Attainment/Unclassifiable
New Jersey

Entire State
Attainment/Unclassifiable
New Mexico

Rest of State
Attainment/Unclassifiable
New York*
Monroe County
Monroe
Unclassifiable

Rest of State
Attainment/Unclassifiable
North Carolina*

Rest of State
Attainment/Unclassifiable
North Dakota*

Rest of State
Attainment/Unclassifiable
Ohio

Rest of State
Attainment/Unclassifiable
Oklahoma*

Rest of State
Attainment/Unclassifiable
Oregon

Entire State
Attainment/Unclassifiable
Pennsylvania*
Allegheny
Allegheny (p)
Unclassifiable
Cambria
County
Cambria
Unclassifiable
Carbon-
Schuylkill Area
Carbon
Schuylkill
Unclassifiable
Clearfield
County
Clearfield
Unclassifiable
Lawrence
County
Lawrence
Unclassifiable

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State
Area Name
Counties
(p) = partial county
EPA Final Designation

Lehigh
Northampton
Area
Lehigh
Northampton
Unclassifiable

Rest of State
Attainment/Unclassifiable
Puerto Rico
(municipalities)
San Juan, PR
Catano
Toa Baja (p)
San Juan (p)
Guaynabo (p)
Bayamon (p)
Nonattainment
Guayama-
Salinas, PR
Salinas (p)
Nonattainment

Rest of Territory
Attainment/Unclassifiable
Rhode Island

Entire State
Attainment/Unclassifiable
South Carolina

Entire State
Attainment/Unclassifiable
South Dakota

Rest of State
Attainment/Unclassifiable
Tennessee

Rest of State
Attainment/Unclassifiable
Texas*

Rest of State
Attainment/Unclassifiable
Utah

Entire State
Attainment/Unclassifiable
Vermont

Entire State
Attainment/Unclassifiable
Virginia*
Buchanan
County
Buchanan
Unclassifiable

Rest of State
Attainment/Unclassifiable
Virgin Islands

Entire Territory
Attainment/Unclassifiable
Washington*
Lewis County
Lewis
Unclassifiable
Thurston
County
Thurston
Unclassifiable

Rest of State
Attainment/Unclassifiable
West Virginia*
Wood County
Wood
Unclassifiable

Rest of State
Attainment/Unclassifiable
Wisconsin*

Rest of State
Attainment/Unclassifiable
Wyoming*

Rest of State
Attainment/Unclassifiable
*Areas remain that will be designated by December 31, 2020. "Rest of State" in these cases
means all areas of the state except for those that will be designated by December 31, 2020. For
these areas, states chose to install and operate new monitors.

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