NITROGEN DIOXIDE | Occupational Safety and Health Administration

NITROGEN DIOXIDE†

Chemical Identification
CAS #	10102-44-0
Formula	NO₂
Synonyms	diesel exhaust component, dinitrogen tetroxide (N₂O₄), NO₂, nitrogen peroxide, nitrogen tetroxide

Physical Properties
Physical description	Yellowish-brown liquid or reddish-brown gas (above 70°F) with a pungent, acrid odor.
Boiling point	70°F	Molecular weight	46
Freezing point/melting point	15°F	Vapor pressure	720 mmHg
Flash point		Vapor density	2.62
Specific gravity	1.44 (liquid at 68°F)	Ionization potential	9.75 eV
Lower explosive limit (LEL)		Upper explosive limit (UEL)
NFPA health rating	3	NFPA fire rating	0
NFPA reactivity rating	0	NFPA special instruction	OX: Possesses oxidizing properties
Vapor hazard ratio (VHR)
Historical exceedance percentage
Target organs

Monitoring Methods Used by OSHA
Analyte code (IMIS no.)	1903
Sampling group
Sampler/Sampling media	2-section tube packed with a 400 mg TEA-IMS front and a 200 mg back-up section [SKC 226-40-02]
Sampling time^*	15 min
Sampling volume (TWA)^*
Sampling flow rate (TWA)^*
Sampling volume (STEL/Peak/C)^*	3 L
Sampling flow rate (STEL/Peak/C)^*	0.2 L/min
Analytical method instruments	IC
Method reference	OSHA ID-182 (fully validated)
Notes	Submit as a separate sample.
Special requirements

^* All sampling instructions above are recommended guidelines for OSHA Compliance Safety and Health Officers (CSHOs), please see the corresponding OSHA method reference for complete details.

Bulk/Wipe Method
Wipe Sampler/Sampling media
Bulk Method

On-Site Screening Techniques
Device	CMS Chip
Model/Type	Nitrogen dioxide, 0.5-25 ppm range
Sampling information (see manufacturer instructions)

**Exposure Limits**
OSHA PEL 8-hour TWA (ST) STEL (C) Ceiling Peak		NIOSH REL Up to 10-hour TWA (ST) STEL (C) Ceiling		ACGIH TLV© 8-hour TWA (ST) STEL (C) Ceiling		CAL/OSHA PEL 8-hour TWA (ST) STEL (C) Ceiling Peak
PEL-TWA		REL-TWA		TLV-TWA		PEL-TWA
PEL-STEL		REL-STEL	1 ppm (1.8 mg/m³)	TLV-STEL		PEL-STEL	1 ppm (1.8 mg/m³)
PEL-C	5 ppm (9 mg/m³)	REL-C		TLV-C		PEL-C
Skin notation	N	Skin notation	N	Skin notation	N	Skin notation	N
Notes: See 29 CFR 1910.1000 Table Z-1.		Notes:		Notes: Visit the ACGIH TLV site for specific data		Notes:
Health factors: See NIH-NLM PubChem.		IDLH	13 ppm
Carcinogenic classifications: TLV-A4		Notes:
AIHA emergency response planning guidelines - ERPG-1/ERPG-2/ERPG-3: 1 ppm/15 ppm/30 ppm

Additional Resources and Literature References

NOAA: CAMEO Chemicals - Nitrogen dioxide

NIOSH: Pocket Guide to Chemical Hazards - Nitrogen Dioxide

Literature References

ACGIH: Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Nitrogen Dioxide. See annual publication for most recent information.
Douglas, W.W., Hepper, N.G., and Colby, T.V.: Silo-filler's disease. Mayo Clin. Proc. 64(3): 291-304, 1989.
Frampton, M.W., Boscia, J., Roberts, N.J. Jr., Azadniv, M., Torres, A., Cox, C., Morrow, P.E., Nichols, J., Chalupa, D., Frasier, L.M., Gibb, F.R., Speers, D.M., Tsai, Y., Utell, M.J.: Nitrogen dioxide exposure: effects on airway and blood cells. Am J Physiol Lung Cell Mol Physiol. 282(1):L155-65, Jan 2002.
Helleday, R., Huberman, D., Blomberg, A., Stjernberg, N., Sandstrom, T.: Nitrogen dioxide exposure impairs the frequency of the mucociliary activity. Eur Respir J. 8(10):1664-8, Oct 1995.
Linaker, C.H., Coggon, D., Holgate, S.T., Clough, J., Josephs, L., Chauhan, A.J., Inskip, H.M.: Personal exposure to nitrogen dioxide and risk of airflow obstruction in asthmatic children with upper respiratory infection. Thorax. 55(11):930-3, Nov 2000.
NIOSH: Criteria for a Recommended Standard - Occupational Exposure to Oxides of Nitrogen (Nitrogen Dioxide and Nitric Oxide). 1976.
NIOSH: Occupational Health Guideline for Nitrogen Dioxide. 1978.
Pathmanathan, S., Krishna, M.T., Blomberg, A., Helleday, R., Kelly, F.J., Sandstrom, T., Holgate, S.T., Wilson, S.J., Frew, A.J.: Repeated daily exposure to 2 ppm nitrogen dioxide upregulates the expression of IL-5, IL-10, IL-13, and ICAM-1 in the bronchial epithelium of healthy human airways. Occup Environ Med. 60(11):892-6, Nov 2003.
Roger, L.J., Horstman, D.H., McDonnell, W., Kehrl, H., Ives, P.J., Seal, E., Chapman, R., Massaro, E.: Pulmonary function, airway responsiveness, and respiratory symptoms in asthmatics following exercise in NO2. Toxicol Ind Health. 6(1):155-71, Jan 1990.

Last Updated Date : 04/15/2025

NITROGEN DIOXIDE†

Chemical Identification

Physical Properties

Monitoring Methods Used by OSHA

Bulk/Wipe Method

On-Site Screening Techniques

Exposure Limits

Additional Resources and Literature References