version of this
fact sheet (PDF, 78 KB)
What is nitrogen dioxide?
Nitrogen dioxide (NO2) is a red-brown gas produced when fuel burns. It is present in
vehicle exhaust and the fumes from burning fuel oil, kerosene, propane, natural gas or
wood. Appliances such as gas stoves, portable heaters, fireplaces, and gas-fueled clothes
dryers may produce this gas. When NO2 is exposed to water, it can form nitric acid, which
is a chemical that contributes to acid rain. Nitrogen dioxide is also a major cause of
How can I be exposed to nitrogen dioxide?
People are exposed to NO2 by breathing in the gas from polluted air. The levels of NO2
are usually higher outdoors than indoors. The operation of gas or diesel engines in indoor
areas can result in a build up of dangerous levels of NO2 in the air. For example, several
hockey players were poisoned by NO2 when a fuel-powered ice-resurfacing machine released
this gas into an indoor ice skating rink. The players experienced severe coughing and
other flu-like symptoms.
In addition to fuel powered engines, home appliances, such as gas ovens, furnaces, and
wood stoves can also release NO2 into the air. When these energy sources burn fuel
incompletely, there is the risk of NO2 being produced. In silos, NO2 can also be released
by corn, hay, silage, or grain as they ferment. Gases produced by electric arc welding may
also contain dangerous levels of nitrogen dioxide. Traces of NO2 can be found in tobacco
What are the effects of exposure to nitrogen dioxide?
Breathing low levels of nitrogen dioxide can cause a slight cough, mild fatigue, and
nausea. Eye, nose, and throat irritation are also common symptoms. At high concentrations,
NO2 can cause severe coughing, choking, headache, nausea, abdominal pain, and shortness of
breath. If the exposure is severe, symptoms may continue after the exposure has ended,
causing difficulty breathing for weeks.
How can I avoid being exposed to nitrogen dioxide?
- Have gas appliances professionally inspected each year.
- Be sure that all gas appliances are properly vented to the outdoors.
- Keep fireplace flues fully open and clear of obstructions when in use.
- Never idle a car inside a garage or car port.
- Make sure that wood stoves are correctly installed and vented.
- Have your home heating system and chimney professionally inspected each year.
What should I do if I suspect a problem?
If you suspect NO2 exposure, and can identify the source (e.g. a gas engine), turn off
the source and get fresh air into the area. Open windows and doors. Use a fan if necessary
to increase air circulation.
If you experience unexplained symptoms such as cough, fatigue, eye and nose irritation
that go away when you leave home, NO2 poisoning may be occurring in your home.
Elderly people, young children, and people with chronic respiratory diseases, such as
asthma and emphysema, may be very sensitive to NO2; they should be evacuated. If the
symptoms are causing discomfort or if they are persistent, consult your doctor.
If you suspect that a device in your home, such as a stove, is releasing NO2, call your
local gas utility or a heating contractor for a home inspection. Once the NO2 source is
identified, repair, replacement, or proper ventilation of the appliance can eliminate the
Back to index page
Health Resource Directory
PPH 7104 11/2000
September 03, 2014