Air quality index - a number for reporting air quality.The numbers range from 0 - parts per million.The higher the index, the more harmful it is for the environment.

Aerosols - very small particles of gas and other substances that "float" in the air.

Atmosphere - the whole mass of air surrounding the earth.

Control strategy - a number targeted towards improving ozone (0.1200 ppmís).

Design ratio - a quotient representing the number of VOCís to the number of NOx used to reduce ozone.

Emissions - substances discharged into the air by smokestacks or gasoline engines mainly vehicles.

EPA - Environmental Protection Agency which protects human health and safeguards.

Haze -fine dust, smoke or light vapor causing a lack of transparency of the air.

Interpolation- statistically estimating values of a function between two know values.

Isopleth graph - an isoline on a graph showing the occurrence or frequency of a phenomenon as a function of two variables.

Inversion - an increase of temperature with height through a layer of air.The usual case in the atmosphere is that the warmer air is at or near the earthís surface and the cooler increases as you go up the troposphere.

Latitude - the angular distance north or south from the earthís equator measured through 90 degrees.

Longitude - the portion of the earthís equator intersected between the meridian of the given place and the prime meridian and expressed either in degrees or in time.

Meteorology - another name for the study of weather. Meteorologists are people who study the behavior of the weather. Some meteorologists work on television, but most meteorologists work for the government or other organizations.

Mixing height - the top of a surface based layer of air which is well mixed due to a mechanical and thermal turbulence.

Nitrogen oxides - one of the oxides of nitrogens which is developed through combustion and is also considered a pollutant.

Ozone depletion - loss of ozone.

Ozone - three atomic molecules which make a bluish kind of gas in the atmosphere with a pungent odor.It is considered to be a major pollutant in the lower atmosphere but a beneficial component in the upper atmosphere.

Parts per million -the unit of measurement for ozone.

Ratio - a relationship of two different objects represented as a quotient.

Smog - a colorless, odorless gas which burns to carbon dioxide and it forms from an incomplete combustion of carbon.See also Ozone.

Stratosphere - the part of the earth's atmosphere which extends from about 7 miles (11 kilometers) above the surface to 31 miles (50 kilometers) and in which temperature increases gradually to about 32 degrees Fahrenheit (0 degrees C) and clouds rarely form.

Troposphere - the lowestpart of the earth's atmosphere in which most weather changes occur and temperature generally decreases rapidly with altitude and which extends from the surface to the bottom of the stratosphere.

Volatile Organic Compounds - organic chemical that are used as ingredients in products many consumer products.

Ultraviolet rays - damaging rays; radiation from the sun.