Ozone is a colorless gas that is not emitted directly into the atmosphere from sources but forms in the atmosphere from a photochemical reaction between volatile organic compounds (VOCs) and nitrogen oxides in the presence of sunlight.
Because meteorological conditions play an important part in the formation of ozone, the Division for Air Quality only monitors for ozone between March 1 and Oct. 31 each year.
Particulate matter is a broad classification of pollutants that consists of very fine solid particles, liquid droplets, or aerosols.
Particulates are categorized according to the particle diameter and the health impacts caused by particles of differing sizes. There are generally three classifications of particulate matter.
· Total Suspended Particulates (TSP) are particles between 10 and 50 microns in diameter.
· PM10 are particles 10 microns or smaller in diameter.
· PM2.5 are particles 2.5 microns or smaller in diameter.
Sulfur dioxide is a colorless gas that has a pungent odor at concentrations exceeding 0.5 parts-per-million. Sulfur dioxide is produced by the combustion of sulfur-containing fuels, ore smelting, petroleum processing and the manufacture of sulfuric acid. Coal-fired power plants are typically the largest sources of sulfur dioxide.
Nitrogen dioxide is a reddish-brown gas that is produced during the high temperature combustion of fossil fuels. The primary sources of nitrogen dioxide are power plants, motor vehicles, incinerators, industrial boilers and some chemical processes.
Lead is one of the naturally occurring metal elements that is classified as a heavy metal and is toxic if inhaled or ingested. Currently smelters and battery plants are the major sources of lead emissions.
Carbon monoxide is an odorless, colorless, poisonous gas that is produced by the incomplete combustion of carbon-containing fuels. The primary source of carbon monoxide is the exhaust from motor vehicles. Other sources include industrial processes and coal, kerosene, and wood-burning stoves in homes.
Air toxics include a wide variety of substances that are known or suspected to cause neurological, immunological, reproductive and respiratory disorders or are known or suspected human carcinogens. Air toxics can generally be divided into four distinct groups: volatile organic compounds, semi-volatile organic compounds, metals, and reactive acidic and caustic gases. Sources include all types of industry, vehicle exhaust, gas stations, dry cleaners, pest control, painting and open burning.
Acid rain includes precipitation in the form of snow, sleet, hail, rain or fog that has a low pH level resulting from emissions of pollutants into the atmosphere.