Nitrogen dioxide

Synonyms

Dinitrogen tetroxide; Dinitrogen tetroxide, liquefied; Nitrogen dioxide, liquefied; Nitrogen oxide; Nitrogen peroxide; Nitrogen peroxide, liquefied; Nitrogen tetroxide; Peroxyde d'azote; [CHEMINFO] UN1067

Category

Oxidizers

Description

Yellowish-brown liquid or reddish-brown gas (above 70 degrees F) with a pungent, acrid odor; Note: In solid form (below 15 degrees F) it is found structurally as N2O4; [NIOSH]

Sources/Uses

Generated from high temperature combustion; a common indoor air pollutant (gas ranges, kerosene heaters and improperly vented gas space heaters); occupational exposures have occurred after oxyacetylene welding, after underground blasting in mining operations, and after entering freshly filled farm silos. Other activities associated with increased NO2 levels include: glassblowing; operating motor vehicles indoors (including ice skating rink resurfacing machines); manufacture of nitric acid, oxidized cellulose compounds, lacquers and dyes, rocket propellants, and fertilizers; brazing; metal cleaning; rayon and food bleaching; fire fighting. [Rom, p. 1467]

Comments

Silo-filler's disease is an acute condition caused by NO2. [Sullivan, p. 818] This often fatal disease occurs when farmers enter a silo 1 to 10 days after fresh silage has been stored. Like phosgene and ozone, it is less soluble that other irritant inhalants and more likely to cause severe pulmonary edema without the signs of severe upper respiratory injury. (See Comments for phosgene.) [LaDou, p. 563] NO2 poisoning may also cause methemoglobinemia. [Ford, p. 685] Blasting and diesel powered machines generate NO2 at levels of 0.02-0.8 ppm during tunnel construction. " . . . Cumulative exposure to nitrogen dioxide showed the strongest association with a decrease in FEV1 in both non-smokers, and ever smokers." Two studies of miners exposed to nitrogen dioxide at 0.02-0.1 ppm found no effect on lung function. [Reference #2] Heavier than air--accumulates in enclosed spaces; TLV Basis = lower respiratory tract irritant; [ACGIH] Nitrogen dioxide is fibrogenic to the lungs in the context of an acute inhalation exposure complicated by bronchiolitis obliterans.

Reference Link #1

Biomedical References

Insufficient data

Yes

0.2 ppm

Ceiling(OSHA) = 5 ppm

0.5 ppm

13 ppm

Excerpts from Documentation for IDLHs

It has been reported that 10 to 20 ppm has been mildly irritating [Patty 1963]. Exposure to 150 ppm or more (no time period given) has been reported to cause death from pulmonary edema [NRC 1979]. It has been predicted that 50% lethality would occur following exposure to 174 ppm for 1 hour [Book 1982].

900 mm Hg

0.05 ppm

Odor Threshold High

0.14 ppm

LC50 (rat) = 88 ppm/4H

Explanatory Notes

Odor threshold from AIHA (odor character = "bleach"); VP from HSDB;

Reference Link #2

will not burn

1 ppm

15 ppm

30 ppm

Yes

Yes

Yes

MetHgb is secondary toxic effect

Not Classifiable

Diseases

Occupational diseases associated with exposure to this agent:

• Bronchiolitis obliterans
• Pneumonitis, toxic
• Pulmonary disease, chronic obstructive

Processes

Industrial Processes with risk of exposure:

• Acid and Alkali Cleaning of Metals
• Burning Celluloid
• Burning Natural Polymers
• Burning Synthetic Polymers
• Electroplating
• Farming (Respiratory Hazards)
• Firefighting
• Gas Welding and Cutting
• Glass Manufacturing
• Heat Treating
• Metal Thermal Spraying
• Mining
• Petroleum Production and Refining
• Pulp and Paper Processing
• Welding

Activities

Activities with risk of exposure:

• Burning biomass fuel for cooking and heating
• Ceramics making
• Enameling
• Glassblowing
• Intalagio printing
• Lithography printing
• Smoking cigarettes