Skip Navigation

Tox Town - Environmental health concerns and toxic chemicals where you live, work, and play
Nitrogen Oxidesen español
Nitrogen oxides are found in vehicle exhaust,cigarette smoke, and smog.

What are nitrogen oxides?

Nitrogen oxides are a group of gases that are composed of nitrogen and oxygen. Two of the most common nitrogen oxides are nitric oxide and nitrogen dioxide. The chemical formula for nitric oxide is NO; for nitrogen dioxide, it is NO2. Nitrous oxide, N2O, is a greenhouse gas that contributes to climate change.

Nitric oxide is a gas with a sharp, sweet smell; it is colorless to brown at room temperature. Nitrogen dioxide is a colorless to brown liquid at room temperature, with a strong, harsh odor. It becomes a reddish-brown gas at temperatures above 70 degrees F. 

Nitrogen oxides are released into the air from motor vehicle exhaust or the burning of coal, oil, diesel fuel, and natural gas, especially from electric power plants. They are also released during industrial processes such as welding, electroplating, engraving, and dynamite blasting. Nitrogen oxides are also produced by cigarette smoking.

Nitrogen oxides, when combined with volatile organic compounds, form ground-level ozone, or smog.  Sulfur dioxide and nitrogen oxides react with precipitation, oxygen, and other substances in the atmosphere to form acid rain.

Nitric oxide is used to bleach rayon and produce nitric acid. Nitrogen dioxide is used to produce rocket fuels, explosives, and other chemicals. Nitrogen dioxide is sometimes used to bleach flour.

How might I be exposed to nitrogen oxides?

Nitrogen oxides are common pollutants found in most of the air in the United States. You can be exposed to nitrogen oxides outdoors by breathing air that contains it, especially if you live near a coal-burning electric power plant or areas with heavy motor vehicle traffic. You can be exposed to higher levels if air pollution and smog levels are high. 

You can be exposed at home if you burn wood or use a kerosene heater or gas stove. 

You can be exposed at home or at work, indoors or outdoors, through smoking cigarettes or breathing second-hand cigarette smoke. 

You can be exposed at work if you work in a facility that produces nitric acid, explosives such as dynamite and TNT, or welded metals.

How can nitrogen oxides affect my health?

Exposure to high industrial levels of nitric oxide and nitrogen dioxide can cause death. It can cause collapse, rapid burning and swelling of tissues in the throat and upper respiratory tract, difficult breathing, throat spasms, and fluid build-up in the lungs. It can interfere with the blood's ability to carry oxygen through the body, causing headache, fatigue, dizziness, and a blue color to the skin and lips. 

Industrial exposure to nitrogen dioxide may cause genetic mutations, damage a developing fetus, and decrease fertility in women. Repeated exposure to high levels of nitrogen dioxide may lead to permanent lung damage. Industrial exposure to nitric oxide can cause unconsciousness, vomiting, mental confusion, and damage to the teeth. Industrial skin or eye contact with high concentrations of nitrogen oxide gases or nitrogen dioxide liquid can cause serious burns. 

Long-term exposure to nitrogen oxides in smog can trigger serious respiratory problems, including damage to lung tissue and reduction in lung function. Exposure to low levels of nitrogen oxides in smog can irritate the eyes, nose, throat, and lungs. It can cause coughing, shortness of breath, fatigue, and nausea. 

If you think you have been exposed to nitrogen oxides, contact your health care professional. 

For poisoning emergencies or questions about possible poisons, please contact your local poison control center at 1-800-222-1222.

This description is based on the information found in the Web links listed with this topic.


Web Links from MedlinePlus (National Library of Medicine)
Air Pollution

More Links
Acid Rain (Environmental Protection Agency)
Acid Rain Students Site (Environmental Protection Agency)
Nitric Oxide. Hazardous Substances Data Bank (National Library of Medicine)
Nitrogen Dioxide (Environmental Protection Agency)
Nitrogen Dioxide. Hazardous Substances Data Bank (National Library of Medicine)
Nitrogen Oxides. ToxFAQs (Agency for Toxic Substances and Disease Registry)

Locations where Nitrogen Oxides may be found: more neighborhoods >>
City
City
Farm
Farm
Town
Town
Airplanes and Air Travel
Climate Change
Construction
Factory
Homes
Hospital
Indoor Air
Offices and Stores
Outdoor Air
Park
School
School Bus
Vehicles
Barn and Silo
Climate Change
Feeding Operation
Homes
Indoor Air
Off-road Vehicles
Outdoor Air
Vehicles
Climate Change
Factory
Homes
Indoor Air
Offices and Stores
Outdoor Air
Park
School
School Bus
Vehicles
<< previous neighborhoods
US Border Regions
US Border Regions
Port
Port
US Southwest
US Southwest
Auto Shop
Border Crossing
Climate Change
Homes
Illegal Dumps and Tire Piles
Indoor Air
Maquiladora
Outdoor Air
Park
Tienda
Trash Burning
Vehicles
Wildfires
Beach
Climate Change
Cruise Ship
Homes
Indoor Air
Marina and Boats
Offices and Stores
Outdoor Air
Shipping
Shipyard
Vehicles
Airplanes and Air Travel
Climate Change
Coal-Fired Power Plants
Homes
Illegal Dumps and Tire Piles
Indoor Air
Off-road Vehicles
Oil and Gas Fields
Outdoor Air
Trash Burning
Vehicles
Wildfires

Last Updated: August 8, 2013

Interactive Graphic Neighborhoods City Farm Town US Border Regions Port US Southwest