Air Quality Definitions

​Acid precipitation or acid rain: Water falling in drops condensed from vapor in the atmosphere with acidic qualities. Principal components typically include nitric and sulfuric acid with water vapor.

Air pollutants: Solids, liquids, or gases which, if discharged into the air, may result in statutory air pollution.

Air pollution: Statutory air pollution has the meaning ascribed to it in West Virginia Code §22-5-2.

Ambient air: Generally, the atmosphere; outdoors.

Anions: Negatively charged molecule, such as sulfate and nitrate. In combination with hydrogen, these molecules act as strong acids.

Annual arithmetic mean: The numerical average of the data for the year.

AQI: Air Quality Index.

Attainment: EPA designation that an area meets the National Ambient Air Quality Standards.

24-hour average: The average concentration for a 24-hour period.

CAA: Clean Air Act.

CAAA: Clean Air Act Amendments.

CAIR: Clear Air Interstate Rule.

Cations: Positively charged ions, such as magnesium, sodium, potassium and calcium, that increase pH of water (make it less acidic) when released to solution through mineral weathering and exchange reactions.

CBI: Confidential Business Information.

CEM: Continuous Emissions Monitor.

CFR: Code of Federal Regulations.

CO: Carbon monoxide.

Criteria pollutant: An air pollutant for which certain levels of exposure have been determined to injure health, harm the environment and cause property damage. EPA-developed standards, National Ambient Air Quality Standards, using science-based guidelines as the basis for setting acceptable levels.

CSR: Code of State Rules.

DAQ: Division of Air Quality - Department of Environmental Protection office that administers West Virginia’s air quality management program for the protection of public health, welfare, and the environment.

DEP: Department of Environmental Protection - West Virginia’s regulatory agency charged with protecting and promoting a healthy environment.

EAC: Early Action Compact.

Elements: Chemicals, such as hydrogen, iron, sodium, carbon, nitrogen, or oxygen, whose distinctly different atoms serve as the basic building blocks of all matter. There are 92 naturally occurring elements. Another 15 have been made in laboratories. Two or more elements combine to form compounds that make up most of the world’s matter.

Emissions: Air pollutants exhausted from a unit or source into the atmosphere.

Exceedance: An incident occurring when the concentration of a pollutant in the ambient air is higher than the National Ambient Air Quality Standards.

EPA or U.S. EPA: Environmental Protection Agency, federal agency that oversees the protection of the environment.

FOIA: Freedom of Information Act.

Fossil fuels: Natural gas, petroleum, coal or any form of solid, liquid or gaseous fuel derived from such material.

HAPS: Hazardous Air Pollutants.

HON: Hazardous Organic NESHAP.

HP: Horsepower.

Lbs./hr.: Pounds per hour.

LDAR: Leak Detection and Repair.

MACT: Maximum Achievable Control Technology.

Mercury: A naturally occurring element that is found in air, water and soil. It exists in several forms: elemental or metallic mercury, inorganic mercury compounds, and organic mercury compounds. Elemental or metallic mercury is a shiny, silver-white metal and is liquid at room temperature.

Micrometer (or Micron):  One-millionth of a meter (10-6 meter) or one 25-thousandth of an inch.

Million British Thermal Units per Hour.

MSA: Metropolitan Statistical Area.

NAAQS: National Ambient Air Quality Standards, set by EPA to protect human health and welfare.

NESHAPS: National Emissions Standards for Hazardous Air Pollutants.

Nonattainment: EPA designation that an area does not meet the National Ambient Air Quality Standards.

NOX: Nitrogen oxides.

NSPS: New Source Performance Standards.

O3: Ozone.

Ozone season: The period beginning May 1 and ending on September 30 of the same year.

Pb: Lead.

PM: Particulate matter.

PM2.5:  Particulate Matter less than 2.5 micrometers (or microns) in diameter.

PM10: Particulate Matter less than 10 micrometers (or microns) in diameter.

Particulate matter: Any material, except uncombined water, that exists in a finely divided form as a liquid or solid.

ppb: Parts per billion by volume.

ppm: Parts per million by volume.

Precursor: A substance that is the source of or aids in the formation of another substance.

PSD: Prevention of Significant Deterioration.

psi: Pounds per Square Inch.

Regulated air pollutant: Generall, any air pollutant subject to a standard or other requirement promulgated under sections 111 or 112 of the Clean Air Act, or any air pollutant for which a National Ambient Air Quality Standard has been promulgated including particulate matter, sulfur dioxide, carbon monoxide, nitrogen dioxide, ozone and lead or lead compounds.

SIC: Standard Industrial Classification.

SIP: State Implementation Plan. Plan to attain and maintain the National Ambient Air Quality Standards for criteria pollutants.

SO2: Sulfur dioxide.

Source or stationary source: Any governmental, institutional, commercial or industrial structure, installation, plant, building or facility that emits or has the potential to emit any regulated air pollutant under the Clean Air Act.

Statutory Air Pollution: The discharge into the air by the act of man of substances (liquid, solid, gaseous, organic or inorganic) in a locality, manner and amount as to be injurious to human health or welfare, animal or plant life, or property, or which would interfere with the enjoyment of life or property.

TAP: Toxic Air Pollutant.

TPY: Tons per Year.

TRS: Total Reduced Sulfur.

TSP: Total Suspended Particulate.

μg/m3: Micrograms per cubic meter.

USEPA: Environmental Protection Agency.