osha-1910-119-appendix-a

OSHA 1910.119 Appendix A provides the threshold quantities used for one important PSM coverage route. The official table identifies each entry by chemical name, Chemical Abstracts Service number where available, and threshold quantity in pounds.

Use the searchable table below as a working reference, then verify every coverage decision against OSHA’s live Appendix A table and the complete 29 CFR 1910.119 standard. Chemical identity, concentration, inventory, process boundaries, interconnection, proximity, and exceptions can all affect the analysis.

OSHA 1910.119 Appendix A and PSM Coverage

Paragraph 1910.119(a)(1)(i) applies PSM to a process involving a chemical at or above the threshold quantity specified in Appendix A. Appendix A is one coverage route. Paragraph (a)(1)(ii) separately addresses certain quantities of Category 1 flammable gases and flammable liquids with flashpoints below 100°F (37.8°C), subject to stated exceptions. Explosives and pyrotechnics manufacturing also has a specific PSM connection through 1910.109(k).

Appendix A quantities are not workplace exposure limits. They are threshold quantities used for PSM applicability. Exposure limits, environmental-reporting thresholds, fire-code limits, and EPA Risk Management Program thresholds serve different purposes and should not be substituted OSHA 1910.119 Appendix A automatically.

How to use the chemical table

1. Build an inventory of chemicals and mixtures associated with the process.
2. Verify chemical identity using the name, synonyms, Safety Data Sheet, and CAS number.
3. Check whether Appendix A specifies a concentration.
4. Determine the maximum quantity that could be involved in the process, not only the average daily inventory.
5. Evaluate interconnected vessels and separate vessels located so a highly hazardous chemical could be involved in a potential release.
6. Compare the covered amount with the listed threshold quantity.
7. Evaluate other PSM coverage routes and exceptions.
8. Document data sources, assumptions, calculations, process boundary, and OSHA 1910.119 Appendix A approval.

Chemical name, CAS number, and concentration

Names can vary across purchasing records, SDSs, laboratory systems, and operating documents. The CAS number helps distinguish substances with similar names, but some Appendix A entries state “None” or “Varies.” Use the entire entry, including synonyms and concentration language.

Several entries specify a concentration, such as ammonia solutions above 44 percent ammonia by weight, hydrogen peroxide at 52 percent by weight or greater, or nitric acid at 94.5 percent by weight or greater. Do not drop the concentration qualifier when screening OSHA 1910.119 Appendix A inventory.

Mixtures and commercial-grade chemicals

Mixture analysis can be complex. OSHA’s 1994 threshold-quantity interpretation discusses commercial-grade concentrations, entries with stated weight percentages, and examples of how amounts in mixtures may be evaluated. Older interpretations should be read with the current regulatory text because interpretations explain specific circumstances and can be affected by later developments.

Do not use a universal formula for every mixture without verifying the applicable entry and OSHA guidance. Record the composition source, concentration basis, maximum credible amount, calculation units, and treatment OSHA 1910.119 Appendix A of all connected OSHA 1910.119 Appendix A inventory.

Process boundaries, interconnection, and proximity

The threshold analysis applies to a “process,” not automatically to each vessel in isolation. Under the PSM definition, interconnected vessels are considered a single process. Separate vessels can also be considered a single process when located so that a highly hazardous chemical could be involved in a potential release.

Use current block flow and process flow diagrams, P&IDs, inventories, transfer arrangements, and facility layouts to define the boundary. Document shared piping, temporary connections, common containment areas, and credible release OSHA 1910.119 Appendix A interactions.

Current OSHA Appendix A chemical table

The OSHA 1910.119 Appendix A table identifies chemicals by name, CAS number, and threshold quantity. The table is reproduced from OSHA’s current online Appendix A page as reviewed on 11 August 2026. TQ means threshold quantity in pounds. Use your browser’s page-search function to find a chemical name or OSHA 1910.119 Appendix A CAS number.

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CHEMICAL name	CAS*	TQ**
Acetaldehyde	75-07-0	2500
Acrolein (2-Propenal)	107-02-8	150
Acrylyl Chloride	814-68-6	250
Allyl Chloride	107-05-1	1000
Allylamine	107-11-9	1000
Alkylaluminums	Varies	5000
Ammonia, Anhydrous	7664-41-7	10000
Ammonia solutions (>44% ammonia by weight)	7664-41-7	15000
Ammonium Perchlorate	7790-98-9	7500
Ammonium Permanganate	7787-36-2	7500
Arsine (also called Arsenic Hydride)	7784-42-1	100
Bis(Chloromethyl) Ether	542-88-1	100
Boron Trichloride	10294-34-5	2500
Boron Trifluoride	7637-07-2	250
Bromine	7726-95-6	1500
Bromine Chloride	13863-41-7	1500
Bromine Pentafluoride	7789-30-2	2500
Bromine Trifluoride	7787-71-5	15000
3-Bromopropyne (also called Propargyl Bromide)	106-96-7	100
Butyl Hydroperoxide (Tertiary)	75-91-2	5000
Butyl Perbenzoate (Tertiary)	614-45-9	7500
Carbonyl Chloride (see Phosgene)	75-44-5	100
Carbonyl Fluoride	353-50-4	2500
Cellulose Nitrate (concentration >12.6% nitrogen)	9004-70-0	2500
Chlorine	7782-50-5	1500
Chlorine Dioxide	10049-04-4	1000
Chlorine Pentrafluoride	13637-63-3	1000
Chlorine Trifluoride	7790-91-2	1000
Chlorodiethylaluminum (also called Diethylaluminum Chloride)	96-10-6	5000
1-Chloro-2,4-Dinitrobenzene	97-00-7	5000
Chloromethyl Methyl Ether	107-30-2	500
Chloropicrin	76-06-2	500
Chloropicrin and Methyl Bromide mixture	None	1500
Chloropicrin and Methyl Chloride mixture	None	1500
Cumene Hydroperoxide	80-15-9	5000
Cyanogen	460-19-5	2500
Cyanogen Chloride	506-77-4	500
Cyanuric Fluoride	675-14-9	100
Diacetyl Peroxide (Concentration >70%)	110-22-5	5000
Diazomethane	334-88-3	500
Dibenzoyl Peroxide	94-36-0	7500
Diborane	19287-45-7	100
Dibutyl Peroxide (Tertiary)	110-05-4	5000
Dichloro Acetylene	7572-29-4	250
Dichlorosilane	4109-96-0	2500
Diethylzinc	557-20-0	10000
Diisopropyl Peroxydicarbonate	105-64-6	7500
Dilaluroyl Peroxide	105-74-8	7500
Dimethyldichlorosilane	75-78-5	1000
Dimethylhydrazine, 1,1-	57-14-7	1000
Dimethylamine, Anhydrous	124-40-3	2500
2,4-Dinitroaniline	97-02-9	5000
Ethyl Methyl Ketone Peroxide (also Methyl Ethyl Ketone Peroxide; concentration >60%)	1338-23-4	5000
Ethyl Nitrite	109-95-5	5000
Ethylamine	75-04-7	7500
Ethylene Fluorohydrin	371-62-0	100
Ethylene Oxide	75-21-8	5000
Ethyleneimine	151-56-4	1000
Fluorine	7782-41-4	1000
Formaldehyde (Formalin)	50-00-0	1000
Furan	110-00-9	500
Hexafluoroacetone	684-16-2	5000
Hydrochloric Acid, Anhydrous	7647-01-0	5000
Hydrofluoric Acid, Anhydrous	7664-39-3	1000
Hydrogen Bromide	10035-10-6	5000
Hydrogen Chloride	7647-01-0	5000
Hydrogen Cyanide, Anhydrous	74-90-8	1000
Hydrogen Fluoride	7664-39-3	1000
Hydrogen Peroxide (52% by weight or greater)	7722-84-1	7500
Hydrogen Selenide	7783-07-5	150
Hydrogen Sulfide	7783-06-4	1500
Hydroxylamine	7803-49-8	2500
Iron, Pentacarbonyl	13463-40-6	250
Isopropylamine	75-31-0	5000
Ketene	463-51-4	100
Methacrylaldehyde	78-85-3	1000
Methacryloyl Chloride	920-46-7	150
Methacryloyloxyethyl Isocyanate	30674-80-7	100
Methyl Acrylonitrile	126-98-7	250
Methylamine, Anhydrous	74-89-5	1000
Methyl Bromide	74-83-9	2500
Methyl Chloride	74-87-3	15000
Methyl Chloroformate	79-22-1	500
Methyl Ethyl Ketone Peroxide (concentration >60%)	1338-23-4	5000
Methyl Fluoroacetate	453-18-9	100
Methyl Fluorosulfate	421-20-5	100
Methyl Hydrazine	60-34-4	100
Methyl Iodide	74-88-4	7500
Methyl Isocyanate	624-83-9	250
Methyl Mercaptan	74-93-1	5000
Methyl Vinyl Ketone	78-94-4	100
Methyltrichlorosilane	75-79-6	500
Nickel Carbonly (Nickel Tetracarbonyl)	13463-39-3	150
Nitric Acid (94.5% by weight or greater)	7697-37-2	500
Nitric Oxide	10102-43-9	250
Nitroaniline (para Nitroaniline	100-01-6	5000
Nitromethane	75-52-5	2500
Nitrogen Dioxide	10102-44-0	250
Nitrogen Oxides (NO; NO2; N204; N203)	10102-44-0	250
Nitrogen Tetroxide (also called Nitrogen Peroxide)	10544-72-6	250
Nitrogen Trifluoride	7783-54-2	5000
Nitrogen Trioxide	10544-73-7	250
Oleum (65% to 80% by weight; also called Fuming Sulfuric Acid)	8014-95-7	1,000
Osmium Tetroxide	20816-12-0	100
Oxygen Difluoride (Fluorine Monoxide)	7783-41-7	100
Ozone	10028-15-6	100
Pentaborane	19624-22-7	100
Peracetic Acid (concentration >60% Acetic Acid; also called Peroxyacetic Acid)	79-21-0	1000
Perchloric Acid (concentration >60% by weight)	7601-90-3	5000
Perchloromethyl Mercaptan	594-42-3	150
Perchloryl Fluoride	7616-94-6	5000
Peroxyacetic Acid (concentration >60% Acetic Acid; also called Peracetic Acid)	79-21-0	1000
Phosgene (also called Carbonyl Chloride)	75-44-5	100
Phosphine (Hydrogen Phosphide)	7803-51-2	100
Phosphorus Oxychloride (also called Phosphoryl Chloride)	10025-87-3	1000
Phosphorus Trichloride	7719-12-2	1000
Phosphoryl Chloride (also called Phosphorus Oxychloride)	10025-87-3	1000
Propargyl Bromide	106-96-7	100
Propyl Nitrate	627-3-4	2500
Sarin	107-44-8	100
Selenium Hexafluoride	7783-79-1	1000
Stibine (Antimony Hydride)	7803-52-3	500
Sulfur Dioxide (liquid)	7446-09-5	1000
Sulfur Pentafluoride	5714-22-7	250
Sulfur Tetrafluoride	7783-60-0	250
Sulfur Trioxide (also called Sulfuric Anhydride)	7446-11-9	1000
Sulfuric Anhydride (also called Sulfur Trioxide)	7446-11-9	1000
Tellurium Hexafluoride	7783-80-4	250
Tetrafluoroethylene	116-14-3	5000
Tetrafluorohydrazine	10036-47-2	5000
Tetramethyl Lead	75-74-1	1000
Thionyl Chloride	7719-09-7	250
Trichloro (chloromethyl) Silane	1558-25-4	100
Trichloro (dichlorophenyl) Silane	27137-85-5	2500
Trichlorosilane	10025-78-2	5000
Trifluorochloroethylene	79-38-9	10000
Trimethyoxysilane	2487-90-3	1500

Coverage-review checklist

• Has each substance been checked by name, synonym, and CAS number?
• Are concentration qualifiers preserved?
• Does the quantity represent the maximum amount that could be involved?
• Are interconnected and proximate inventories included in the process analysis?
• Have mixtures and commercial-grade concentrations been evaluated using applicable guidance?
• Have flammable-material and 1910.109 manufacturing routes also been checked?
• Are all claimed exceptions supported by current facts?
• Is the determination documented and approved by qualified OSHA 1910.119 Appendix A personnel?

Common Appendix A mistakes

• Searching only by a familiar product name and missing the listed chemical identity;
• Ignoring a concentration qualifier;
• Using average inventory instead of the amount that can be involved in the process;
• Dividing interconnected equipment into artificial smaller inventories;
• Assuming every mixture is treated by the same calculation;
• Confusing a PSM threshold with an occupational exposure limit;
• Ignoring a separate flammable-material or explosives-manufacturing coverage route; and
• Relying on an old copied table instead of verifying the official OSHA 1910.119 Appendix A current source.

Related PSM requirements

• OSHA Process Safety Management overview
• Process Safety Information
• OSHA 1910.109 explosives and PSM coverage
• Block flow and process flow diagrams