A reactive chemical compound of 3 oxygen atoms found at all levels of the atmosphere. Ozone is unhealthy to breathe, particularly for children and other sensitive groups, and it can damage trees and crops. Power plants and motor vehicles are the main sources of ozone-forming pollution in North Carolina. Ozone values are shown both as one-hour averages and eight-hour averages. Historically, there was an ambient air standard for one-hour averages, but it was revoked nationally in June, 2005 and phased out for all areas of North Carolina by April, 2009. The 8-hour average ambient air standard is 0.076 ppm (76 ppb).
Carbon Monoxide (CO):
The most commonly occurring air pollutant. Carbon monoxide (CO) is a colorless and poisonous gas produced by incomplete burning of carbon-containing fuel. Breathing carbon monoxide affects the oxygen-carrying capacity of the blood. Hemoglobin in the blood binds with CO more readily than with oxygen, starving the body of vital oxygen. Individuals with anemia, lung and heart diseases are particularly sensitive to CO effects. Low concentrations affect mental function, vision and alertness. High concentrations can cause fatigue, reduced work capacity and may adversely affect fetal development. Chronic exposure to CO at concentrations of 70 ppm (70,000 ppb) or greater can cause cardiac damage. Other health effects associated with exposure to CO include central nervous system effects and pulmonary function difficulties. The CO value shown is a one-hour average. The 8-hour standard is 9 ppm (9,000 ppb), and the 1-hour standard is 35 ppm (35,000 ppb).
A colorless gas with a pungent and suffocating odor. and the most abundant alkaline gaseous component in our atmosphere. Ammonia is incompatible with, and thus reactive with, strong oxidizers, acids, halogens, and salts of silver and zinc. It is corrosive to copper and galvanized surfaces. Health hazards associated with ammonia are chest pain, skin burns and frostbite. The vapors are extremely irritating and corrosive. There is no ambient air standard for ammonia.
A colorless, corrosive, harmful gas with a pungent odor. Smaller concentrations of sulfur trioxide and other sulfate compounds are also found in sulfur dioxide (SO2) emissions. Sulfur oxides contribute to the formation of acid rain and the formation of particles that reduce visibility. The most obvious health effect of SO2 is irritation and inflammation of body tissues brought in contact with the gas. SO2 can increase the severity of existing respiratory diseases such as asthma, bronchitis, and emphysema. The one-hour health-related standard is 75 ppb. SO2 also has a separate "secondary" standard for protection from adverse effects on vegetation, animals, materials, and other aspects of "well-being" distinct from human health. The secondary standard is a 3-hour average of 500 ppb (0.50 ppm).
Several gaseous oxides of nitrogen are normally found in the atmosphere, including nitrous oxide (N2O), nitric oxide (NO) and nitrogen dioxide (NO2). The combination of NO and NO2 is sometimes generically referred to as NOx. NO and NO2 are monitored extensively because they are precursors of ozone formation. N2O a stable gas with anesthetic characteristics and typical ambient concentrations well below the threshold concentration for a biological effect. NO2 is reddish-brown but is not usually visible at typical ambient concentrations. NO is a colorless gas with ambient concentrations generally low enough to have no significant biological effect. It is rapidly converted in air to NO2. NO reacts with fluorine, combustible materials, ozone, ammonia, chlorinated hydrocarbons, metals and carbon disulfide. It causes eye, nose and throat irritation. NO2 is the only nitrogen oxide subject to an ambient standard. The one-hour ambient standard is 100 ppb. The annual standard for NO2 is an arithmetic mean one-hour average of 53 ppb.
Reactive oxides of nitrogen:
Oxidation of NOx produces other compounds in the atmosphere, and in combination these are referred to as "reactive nitrogen oxides" and usually abbreviated to "NOy". value shown is a one-hour average. There is no ambient hourly air standard for NOy. health effects associated with NOy are similar to those of NO. There is no ambient air standard for NOy.