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west virginia department of environmental protection
west virginia department of environmental protection
west virginia department of environmental protection

National Ambient Air Quality Standards

Overview

The Clean Air Act, which was last amended in 1990, requires U.S. EPA to set National Ambient Air Quality Standards (NAAQS) for pollutants considered harmful to public health and the environment. The Clean Air Act established two types of NAAQS. Primary standards set limits to protect public health, including the health of "sensitive" populations such as asthmatics, children, and the elderly. Secondary standards set limits to protect public welfare, including protection against decreased visibility, damage to animals, crops, vegetation, and buildings.

In October 2020, the entire State of West Virginia was designated as meeting all of the U.S. EPA's health-based NAAQS for the first time since 1978, when the initial nonattainment designations were made under the 1970 Clean Air Act. West Virginia is just the 16th state in the nation to be in attainment with all NAAQS.

Critical Pollutants

The EPA Office of Air Quality Planning and Standards (OAQPS) has set NAAQS for six principle pollutants, which are called "criteria" pollutants - carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter and sulfur dioxide. Units of measure for the standards are parts per million (ppm) by volume, milligrams per cubic meter of air (mg/m3), and micrograms per cubic meter of air (µg/m3).

NAAQS Table

Periodically, the standards are reviewed and sometimes may be revised, establishing new standards. The most recently established standards are listed on the EPA's website.

Carbon monoxide is a colorless, odorless, and (at much higher levels) poisonous gas, formed when carbon in fuels is not burned completely. It is a product of motor vehicle exhaust, which contributes about 60 percent of all CO emissions nationwide. High concentrations of CO generally occur in areas with heavy traffic congestion. In cities, as much as 95 percent of all CO emissions may emanate from automobile exhaust. Other sources of CO emissions include industrial processes such as carbon black manufacturing, non-transportation fuel combustion, and natural sources such as wildfires. Woodstoves, cooking, cigarette smoke, and space heating are sources of CO in indoor environments. Peak CO concentrations typically occur during the colder months of the year when CO automotive emissions are greater and nighttime inversion conditions are more frequent.

All areas of West Virginia are in attainment with the carbon monoxide NAAQS. For more information see the U.S. EPA website.

Lead is a metal found naturally in the environment as well as in manufactured products. The major sources of lead emissions have historically been from fuels in motor vehicles (such as cars and trucks) and industrial sources. Emissions from on-road vehicles decreased 99% between 1970 and 1995 due primarily to the use of unleaded gasoline. Use of leaded gasoline in highway vehicles was prohibited on December 31, 1995. Due to the phase out of leaded gasoline, ore and metals processing is the major source of lead emissions to the air today.

The highest levels of lead in air are generally found near lead smelters. Other stationary sources are waste incinerators, utilities, and lead-acid battery manufacturers. Combustion and smelting processes operate at high temperatures and emit submicron particulate matter lead. Material handling and mechanical operations emit larger particles of lead.

All areas of West Virginia are in attainment with the lead NAAQS.

U.S. EPA is reviewing the current lead NAAQS. For more information see the EPA website.

Nitrogen dioxide (NO2) is one of a group of highly reactive gasses known as "oxides of nitrogen," or "nitrogen oxides (NOx)." Other nitrogen oxides include nitrous acid and nitric acid. While EPA's National Ambient Air Quality Standard covers this entire group of NOx, NO2 is the component of greatest interest and the indicator for the larger group of nitrogen oxides. NO2 forms quickly from emissions from cars, trucks and buses, power plants, and off-road equipment. In addition to contributing to the formation of ground-level ozone, and fine particle pollution, NO2 is linked with a number of adverse effects on the respiratory system.

EPA first set standards for NO2 in 1971, setting both a primary standard (to protect health) and a secondary standard (to protect the public welfare) at 0.053 parts per million (53 ppb), averaged annually. The Agency has reviewed the standards twice since that time, but chose not to revise the standards at the conclusion of each review. All areas in the U.S. meet the current (1971) NO2 standards.

EPA is currently reviewing the NO2 NAAQS. For more information see the EPA website.

Ozone (O3) is a gas composed of three oxygen atoms. It is not usually emitted directly into the air, but at ground-level is created by a chemical reaction between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. Ozone has the same chemical structure whether it occurs miles above the earth or at ground-level and can be "good" or "bad," depending on its location in the atmosphere.

In the earth's lower atmosphere, ground-level ozone is considered "bad." Motor vehicle exhaust and industrial emissions, gasoline vapors, and chemical solvents as well as natural sources emit NOx and VOC that help form ozone. Ground-level ozone is the primary constituent of smog. Sunlight and hot weather cause ground-level ozone to form in harmful concentrations in the air. As a result, it is known as a summertime air pollutant. Many urban areas tend to have high levels of "bad" ozone, but even rural areas are also subject to increased ozone levels because wind carries ozone and pollutants that form it hundreds of miles away from their original sources.

"Good" ozone occurs naturally in the stratosphere approximately 10 to 30 miles above the earth's surface and forms a layer that protects life on earth from the sun's harmful rays.

Ozone Maintenance Areas

1997 8-Hour Ozone Maintenance Areas

These areas are considered attainment with approved Maintenance Plans. Transportation planning organizations responsible for these areas should consult with DAQ prior to revising Long Range Transportation Plans and/or Transportation Improvement Programs.

  • Charleston (Kanawha and Putnam counties)
  • Huntington (Cabell and Wayne counties)
  • Parkersburg (Wood County)
  • Weirton (Brooke and Hancock counties)
  • Wheeling (Marshall and Ohio counties)
2004 Ozone Maintenance Areas

In 2004 EPA designated five areas (11 Counties) as nonattainment areas with respect to the 1997 8-hour ozone NAAQS [69 FR 23858]:

  • Charleston (Kanawha and Putname Counties)
  • Huntington (Cabell and Wayne Counties)
  • Parkersburg (Wood County)
  • Wheeling (Marshall and Ohio Counties)
  • Weirton (Brooke and Hancock Counties)

Based on the 2002-2004 and 2003-2005 design values the DAQ submitted redesignation requests and maintenance plans for the Charleston, Huntington, Parkersburg, Wheeling and Weirton areas. EPA approved the maintenance plans and redesignated each of the areas to attainment.

All areas of West Virginia are in attainment with the 1997 ozone NAAQS.

EPA is currently reviewing the ozone NAAQS. For more information see the EPA website.

The term "particulate matter" (PM) includes both solid particles and liquid droplets found in air. Many manmade and natural sources emit PM directly or emit other pollutants that react in the atmosphere to form PM. These solid and liquid particles come in a wide range of sizes.

Particles less than 10 micrometers in diameter (PM10) pose a health concern because they can be inhaled into and accumulate in the respiratory system Particles less than 2.5 micrometers in diameter (PM2.5) are referred to as "fine"particles and are believed to post the largest health risks. Because of their small size, fine particles can lodge deeply into the lungs. Sources of fine particles include all types of combustion (motor vehicles, power plants, wood burning, etc.) and some industrial processes. Particles with diameters between 2.5 and 10 micrometers are referred to as "coarse." Sources of coarse particles include crushing or grinding operations, and dust from paved or unpaved roads.

For more information regarding the PM10 and PM2.5 NAAQS, please see the EPA website.

PM10

The nation's air quality standards for particulate matter were first established in 1971 and were not significantly revised until 1987, when EPA established the PM10 NAAQS, changing the indicator of the standards to regulate respirable particles less than or equal to 10 microns in diameter (about 1/7th the average width of a human hair).

PM2.5

Ten years later, in 1997, after a lengthy review, EPA revised the PM standards, setting separate standards for fine particles (PM2.5), equal to or less than 2.5 microns in diameter (about 1/30th the average width of a human hair), based on their link to serious health problems ranging from increased symptoms, hospital admissions and emergency room visits for people with heart and lung disease, to premature death in people with heart or lung disease.

In 1997 EPA revised the NAAQS for particulate matter and established primary (health-based) annual and 24-hour standards for PM2.5 [62 FR 38652]. The 1997 annual standard is 15.0 micrograms per cubic meter (µg/m3), based on a 3-year average of annual mean PM2.5 concentrations. The 1997 24-hour standard is 65 µg/m3, based on a 3-year average of the 98th percentile of 24-hour concentrations. [Percentile is a value on a scale that indicates the percent of a distribution that is equal to or below it. For example, a concentration value at the 98th percentile is equal to or greater than 98 percent of the concentration values.] EPA also revised the secondary standards, making them equal to the primary standards.

1997 PM2.5 Maintenance Areas

EPA designated 6 areas (ten counties, and 2 partial counties) in West Virginia as nonattainment with respect to the 1997 PM2.5 NAAQS:

  • Charleston, WV [Kanawha and Putnam Counties]
  • Huntington-Ashland, WV-KY-OH [Cabell and Wayne Counties, and the Graham Tax District in Mason County]
  • Martinsburg, WV-Hagerstown, MD [Berkeley County]
  • Parkersburg-Marietta, WV-OH [Wood County and the Grant Tax District in Pleasants County]
  • Steubenville-Weirton, OH-WV [Brooke and Hancock Counties]
  • Wheeling, WV-OH [Marshall and Ohio Counties]

It should be noted that all the areas designated as nonattainment were not in compliance with the annual standard of 15.0 micrograms per cubic meter (µg/m3), based on a 3-year average of annual mean PM2.5 concentrations. However, all areas of West Virginia were found to be attainment with the co-existing 1997 24-hour standard of 65 µg/m3. The design values for the West Virginia nonattainment area monitors for both the annual and 24-hour standards are presented in this table.

In 2009 EPA determined that the Martinsburg, Parkersburg and Wheeling areas were in attainment with the 1997 standard, based on data for the 3-year period 2006-2008 [74 FR 60199].

As required by the Clean Air Act, the DAQ submitted demonstrations to EPA for incorporation into the State Implementation Plan (SIP) demonstrating that the Parkersburg, Charleston, Huntington and Weirton areas would attainment the 1997 standard by April of 2010. As shown in the table, data for the 3-year period 2007-2009 shows that these areas did attain the standard.

2006 PM2.5 Maintenance Areas

In 2006, EPA revised the primary 24-hour standard for PM2.5 to 35 µg/m3, based on a 3-year average of the 98th percentile of 24-hour concentrations. EPA designated 2 areas (4 counties) in West Virginia nonattainment with respect to the 2006 24-hour standard based on data for the 3-year period 2006-2008 [74 FR 58688].

  • Charleston (Kanawha and Putnam Counties)
  • Weirton (Brooke and Hancock Counties)

For the subsequent 3-year period, 2007-2009, the Charleston are monitored attainment with the 2006 24-hour standard as shown in the table.

Map of WV PM2.5 maintenance areas
PM2.5 Maintenance Areas as of 2015

Sulfur dioxide (SO2) is one of a group of highly reactive gasses known as “oxides of sulfur.” The largest sources of SO2 emissions are from fossil fuel combustion at power plants (66%) and other industrial facilities (29%). Smaller sources of SO2 emissions include industrial processes such as extracting metal from ore, and the burning of high sulfur containing fuels by locomotives, large ships, and non-road equipment. SO2 is linked with a number of adverse effects on the respiratory system.

EPA first set standards for SO2 in 1971. EPA set a 24-hour primary standard at 0.14 ppm and an annual average standard at 0.03 ppm (to protect health). EPA also set a 3-hour average secondary standard at 0.5 ppm (to protect the public welfare).

The last review of the SO2 NAAQS was completed in 1996 and the Agency chose not to revise the standards. In the last review, EPA also considered, but did not set, a five minute NAAQS to protect asthmatics at elevated ventilation rates from bronchoconstriction and respiratory symptoms associated with 5-10 minute peaks of SO2.

All areas of West Virginia are in attainment with the 1971 SO2 NAAQS.

EPA is currently reviewing the SO2 NAAQS. For more information see the EPA website

Sulfur Dioxide Maintenance Areas

1-Hour SO2 Maintenance Areas
  • Cross Creek Tax District of Brooke County
  • Clay, Franklin and Washington Tax Districts of Marshall County
Map of the WV northern panhandle showing 1 hour S02 maintenance areas
WV 1-Hour Sulfur Dioxide Maintenance Areas

Report an Emergency

Imminent Danger: 911
Official Emergency Spill Report
1-800-642-3074
Non-Emergency
1-304-926-0499

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