Nitrogen Dioxide

Nitrogen dioxide is the chemical compound with the formula NO2. It exists as a radical in nature. One of several nitrogen oxides, NO2 is an intermediate in the industrial synthesis of nitric acid, of which millions of tons are produced each year.
This reddish-brown toxic gas has a characteristic sharp, biting odor and is a prominent air pollutant. Nitrogen dioxide typically arises via the oxidation of nitric oxide by oxygen in air.
Nitrogen dioxide is toxic by inhalation, but this could be avoided as the material is acrid and easily detected by our sense of smell. One potential source of exposure is fuming nitric acid, which spontaneously produces NO2 above 0 °C. Symptoms of poisoning (lung edema) tend to appear several hours after one has inhaled a low but potentially fatal dose.
Airmet has several solutions for detection of nitrogen dioxide. Try our product selector below or contact Airmet Scientific for more information.
Nitrogen Dioxide Characteristics
CAS No. 10102-44-0
Chemical formula NO2
Vapour density 1.58 (air = 1)
Safe Work Australia ES TWA 3 ppm
STEL 5 ppm
Flammable limits LEL ---
UEL ---
Equipment group ---
Temperature classification ---
Chemical/physical properties Nitrogen dioxide at room temperature is a reddish-brown, non-flammable gas with a pungent, acrid odour. Below its boiling point of 21.2 °C, it is a pale yellow liquid. 
Hazardous properties Nitrogen dioxide is a powerful lung irritant leading to pulmonary oedema. Exposure to concentrations in the range of 100 to 500 ppm may lead to death from respiratory failure.
Occurrence/Uses Like nitric oxide, nitrogen dioxide is produced due to oxidation of atmospheric nitrogen at high temperatures during combustion, welding and the detonation of explosives.
It is also present in “silo gas” when silage is being stored due to the oxidation of nitric oxide in air.
Detectors available Electrochemical (0 – 150 ppm)
Gas detector tube (0.1 – 1,000 ppm)
Suggested alarm levels Lo: 3 ppm
Hi: 5 ppm


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