| Agent Name |
Nitrogen dioxide |
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| CAS Number |
10102-44-0 |
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| Formula |
N-O2 |
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| Major Category |
Toxic Gases & Vapors |
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| Synonyms |
Dinitrogen tetroxide; Dinitrogen tetroxide, liquefied; Nitrogen dioxide, liquefied; Nitrogen oxide; Nitrogen peroxide; Nitrogen peroxide, liquefied; Nitrogen tetroxide; Peroxyde d'azote; [CHEMINFO] UN1067 |
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| Category |
Oxidizers |
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| 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] |
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| 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] |
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| 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. 522-5] NO2 poisoning may also cause methemoglobinemia. [Ford, p. 685] Blasting and diesel powered machines generate NO2 during tunnel construction. " . . . Cumulative exposure to nitrogen dioxide showed the strongest association with a decrease in FEV1 in both non-smokers and smokers." [See Reference #2] Nitrogen dioxide is fibrogenic to the lungs in the context of an acute inhalation exposure complicated by bronchiolitis obliterans. |
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| Reference Link |
ATSDR Medical Management - Nitrogen oxides |
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| Exposure Assessment |
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| Skin Designation (ACGIH) |
No |
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| TIH |
Yes |
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| TLV (ACGIH) |
3 ppm |
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| STEL (ACGIH) |
5 ppm |
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| PEL (OSHA) | Ceiling(OSHA) = 5 ppm |
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| IDLH (NIOSH) |
20 ppm |
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| 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]. |
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| Vapor Pressure |
720 mm Hg |
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| Odor Threshold Low |
0.05 ppm |
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| Odor Threshold High |
0.14 ppm |
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| Lethal Concentration |
LC50 (rats) = 88 ppm/4H |
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| Explanatory Notes |
Odor threshold from AIHA (odor character = "bleach"); |
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| Reference Link |
Cumulative exposure to dust and gases as determinants of lung function decline in tunnel construction workers. |
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| Flammability (NFPA) |
0: will not burn |
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| Adverse Effects |
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| Toxic Pneumonitis |
Yes |
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| Fibrogenic |
Yes |
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| Methemoglobinemia |
Methemoglobinemia, Secondary |
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| Links to Other NLM Databases |
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| Health Studies |
Human Health Effects from Hazardous Substances Data Bank: NITROGEN DIOXIDE
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