{"data":{"id":"us-va/16vac25-70-100-1","jurisdiction":"us-va","citation":"16VAC25-70-100:1","heading":"APPENDIX A. Concentrations at which some common substances exhibit immediately dangerous to life or health (IDLH) effects","body":"APPENDIX A.\n\nConcentrations at which some common substances exhibit immediately dangerous to life or health (IDLH) effects.\n\nAppendix 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.\n\nAppendix A\n\nCHEMICAL NAME\n\nIDLH LEVELS*\n\nAmmonia\n\n500 ppm\n\nBenzene\n\n2,000 ppm\n\nButadiene\n\n20,000 ppm\n\n2 - Butanone\n\n3,000 ppm\n\nCarbon dioxide\n\n50,000 ppm\n\nCarbon monoxide\n\n1,500 ppm\n\nCarbon tetrachloride\n\n300 ppm\n\nChlorine\n\n25 ppm\n\nChlorobromomethane\n\n5,000 ppm\n\nChloroform\n\n1,000 ppm\n\nCresol\n\n250 ppm\n\nCyclohexane\n\n10,000 ppm\n\nDichlorodifluoromethane\n\n50,000 ppm\n\nDichloromonofluoromethane\n\n50,000 ppm\n\nEthyl acetate\n\n10,000 ppm\n\nFluorotrichloromethane\n\n10,000 ppm\n\nHeptane\n\n4,250 ppm\n\nHexane\n\n5,000 ppm\n\n2 - Hexanone\n\n5,000 ppm\n\nHydrogen chloride\n\n100 ppm\n\nHydrogen sulfide\n\n300 ppm\n\nIsopropyl alcohol\n\n20,000 ppm\n\nLiquefied petroleum gas\n\n19,000 ppm\n\nMethyl alcohol\n\n25,000 ppm\n\nMethyl cellosolve\n\n2,000 ppm\n\nMethyl cellosolve acetate\n\n4,500 ppm\n\nMethyl chloroform\n\n1,000 ppm\n\nMethylene chloride\n\n5,000 ppm\n\nNitric oxide\n\n100 ppm\n\nNitrogen dioxide\n\n50 ppm\n\nOctane\n\n3,750 ppm\n\nOzone\n\n10 ppm\n\nPentane\n\n5,000 ppm\n\nPetroleum distillates mixture\n\n10,000 ppm\n\nPhenol\n\n100 ppm\n\nPhosgene\n\n2 ppm\n\nPropane\n\n20,000 ppm\n\nSodium hydroxide\n\n200 mg/M3\n\nStoddard solvent\n\n5,000 ppm\n\nStyrene\n\n5,000 ppm\n\nSulfur dioxide\n\n100 ppm\n\n1, 1, 2, 2, - Tetrachloro-1, 2 - difluroethane\n\n15,000 ppm\n\nToluene\n\n2,000 ppm\n\nToluene-2, 4-diisocyanate\n\n10 ppm\n\nTrifluoromonobromomethane\n\n50,000 ppm\n\nTurpentine\n\n1,900 ppm\n\nXylene\n\n10,000 ppm\n\n*Reference NIOSH/OSHA Pocket Guide to Chemical Hazards DHEW (NIOSH)   Publication No. 78-210","path":["Title 16. Labor And Employment","Agency 25. Safety And Health Codes Board","Chapter 70. Virginia Confined Space Standard for the Telecommunications Industry"],"source_url":"https://law.lis.virginia.gov/admincode/title16/agency25/chapter70/section100:1/","current_through":"2026 Regular Session (effective July 1, 2026)","vintage":"","retrieved_at":"2026-09-14T04:52:10Z","sha256":"018706a2daf0e5e3c595ac0c1991d79347fb195e57ca9fd1e668568bd83c5e0f","source_id":"us-va-vac","stale":false,"prev":"us-va/16vac25-70-100","next":"us-va/16vac25-70-100-2"},"notice":"GroundRules: Original legal text. Not legal advice."}