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Virginia Administrative Code
Title 16. Labor and Employment
Agency 25. Safety and Health Codes Board
Chapter 70. Virginia Confined Space Standard for the Telecommunications Industry
1/21/2020

16VAC25-70-100:1. Appendix a.

Concentrations at which some common substances exhibit immediately dangerous to life or health (IDLH) effects.

Appendix A is a non-mandatory appendix. According to The National Institute for Occupational Safety and Health (NIOSH) the levels listed below represent a maximum concentration from which one could escape within 30 minutes without any escape-impairing symptoms or any irreversible health effects. These levels were published by NIOSH in September 1985 and are subject to frequent change. This list is not meant to be all inclusive but rather is meant to list some of the more frequently encountered chemicals in confined spaces.

Appendix A

CHEMICAL NAME

IDLH LEVELS*

Ammonia

500 ppm

Benzene

2,000 ppm

Butadiene

20,000 ppm

2 - Butanone

3,000 ppm

Carbon dioxide

50,000 ppm

Carbon monoxide

1,500 ppm

Carbon tetrachloride

300 ppm

Chlorine

25 ppm

Chlorobromomethane

5,000 ppm

Chloroform

1,000 ppm

Cresol

250 ppm

Cyclohexane

10,000 ppm

Dichlorodifluoromethane

50,000 ppm

Dichloromonofluoromethane

50,000 ppm

Ethyl acetate

10,000 ppm

Fluorotrichloromethane

10,000 ppm

Heptane

4,250 ppm

Hexane

5,000 ppm

2 - Hexanone

5,000 ppm

Hydrogen chloride

100 ppm

Hydrogen sulfide

300 ppm

Isopropyl alcohol

20,000 ppm

Liquefied petroleum gas

19,000 ppm

Methyl alcohol

25,000 ppm

Methyl cellosolve

2,000 ppm

Methyl cellosolve acetate

4,500 ppm

Methyl chloroform

1,000 ppm

Methylene chloride

5,000 ppm

Nitric oxide

100 ppm

Nitrogen dioxide

50 ppm

Octane

3,750 ppm

Ozone

10 ppm

Pentane

5,000 ppm

Petroleum distillates mixture

10,000 ppm

Phenol

100 ppm

Phosgene

2 ppm

Propane

20,000 ppm

Sodium hydroxide

200 mg/M3

Stoddard solvent

5,000 ppm

Styrene

5,000 ppm

Sulfur dioxide

100 ppm

1, 1, 2, 2, - Tetrachloro-1, 2 - difluroethane

15,000 ppm

Toluene

2,000 ppm

Toluene-2, 4-diisocyanate

10 ppm

Trifluoromonobromomethane

50,000 ppm

Turpentine

1,900 ppm

Xylene

10,000 ppm

*Reference NIOSH/OSHA Pocket Guide to Chemical Hazards DHEW (NIOSH) Publication No. 78-210

Statutory Authority

§ 40.1-22(5) of the Code of Virginia.

Historical Notes

Derived from VR425-02-30, eff. November 15, 1987; amended, eff. July 1, 1988.

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