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Nitrogen dioxide

May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)

CAS number: 10102–44–0

NIOSH REL: 1 ppm (1.8 mg/m3) STEL

Current OSHA PEL: 5 ppm (9 mg/m3) CEILING

1989 OSHA PEL: 1 ppm (1.8 mg/m3) STEL

1993-1994 ACGIH TLV: 3 ppm (5.6 mg/m3) TWA, 5 ppm (9.4 mg/m3) STEL

Description of substance: Yellowish-brown liquid or reddish-brown gas (above 70°F) with a pungent, acrid odor.

LEL :. . Noncombustible Liquid/Nonflammable Gas

Original (SCP) IDLH: 50 ppm

Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty [1963] that concentrations above 50 ppm are considered dangerous to man for short exposures. Also, NIOSH [1974] cited a rat 4-hour LC50 of 68 ppm [Gray et al. 1954].

Existing short-term exposure guidelines: American Industrial Hygiene Association [AIHA 1964] Emergency Exposure Limits (EELs):

5-minute EEL: 35 ppm

15-minute EEL: 25 ppm

30-minute EEL: 20 ppm

60-minute EEL: 10 ppm

National Research Council [NRC 1985] Short-term Public Emergency Guidance Levels (SPEGLs):

1-hour SPEGL: 1 ppm

2-hour SPEGL: 0.5 ppm

4-hour SPEGL: 0.25 ppm

8-hour SPEGL: 0.12 ppm

16-hour SPEGL: 0.06 ppm

24-hour SPEGL: 0.04 ppm


Lethal concentration data:

Species Reference LC50 (ppm) LCLo (ppm) Time Adjusted 0.5-hrLC (CF*) Derived value
G. pigRabbit






Buckley & Balchum 1965Carson et al. 1962

Gray et al. 1954

Gray et al. 1954

Hialado & Machado 1977

Steadman et al. 1966

Steadman et al. 1966













1 hr15 min

4 hr

30 min

10 min

8 hr

8 hr

37 ppm (1.22)258 ppm (0.82)

123 ppm (1.81)

138 ppm (1.0)

730 ppm (0.73)

141 ppm (2.21)

141 ppm (2.21)

3.7 ppm26 ppm

12 ppm

14 ppm

73 ppm

14 ppm

14 ppm

*Note: Conversion factor (CF) was determined with “n” = 3.5 [ten Berge et al. 1986].

Human data: 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].

Revised IDLH: 20 ppmBasis for revised IDLH: The revised IDLH for nitrogen dioxide is 20 ppm based on acute inhalation toxicity data in humans [Patty 1963]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 20 ppm.


1. American Industrial Hygiene Association, Toxicology Committee [1964]. Emergency exposure limits. Am Ind Hyg Assoc J 25:578-586.

2. Book SA [1982]. Scaling toxicity from laboratory animals to people: an example with nitrogen dioxide. J Toxicol Environ Health 9:719-725.

3. Buckley RD, Balchum OJ [1965]. Acute and chronic exposures to nitrogen dioxide. Effects on oxygen consumption and enzyme activity on guinea pig tissues. Arch Environ Health 10:220-223.

4. Carson TR, Rosenholtz MS, Wilinski FT, Weeks MH [1962]. The responses of animals inhaling nitrogen dioxide for single, short-term exposures. Am Ind Hyg Assoc J 23:457-462.

5. Gray E LeB, Patton FM, Goldberg SB, Kaplan E [1954]. Toxicity of the oxides of nitrogen. II. Acute inhalation toxicity of nitrogen dioxide, red fuming nitric acid, and white fuming nitric acid. AMA Arch Ind Hyg Occup Med 10:418-422.

6. Hialado CJ, Machado AM [1977]. Effect of nitrogen dioxide on Swiss albino mice. J Combustion Toxicol 4:246-253.

7. NIOSH [1974]. QW98000. Nitrogen dioxide. In: The toxic substances list, 1974 ed. Rockville, MD: U.S. Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, DHEW (NIOSH) Publication No. 74-134, p. 534.

8. NRC [1979]. Nitrogen dioxide: an assessment of the health effects of short-term exposure. Washington, DC: National Academy of Sciences, National Research Council, Committee on Toxicology.

9. NRC [1985]. Emergency and continuous exposure guidance levels for selected airborne contaminants. Vol. 4. Washington, DC: National Academy Press, Committee on Toxicology, Board on Toxicology and Environmental Health Hazards, Commission on Life Sciences, National Research Council, pp. 83-95.

10. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., pp. 919-923.

11. Steadman BL, Jones RA, Rector DE, Siegel J [1966]. Effects on experimental animals of long-term continuous inhalation of nitrogen dioxide. Toxicol Appl Pharmacol 9(1):160-170.

12. ten Berge WF, Zwart A, Appelman LM [1986]. Concentration-time mortality response relationship of irritant and systematically acting vapours and gases. J Haz Mat 13:301-309.