Respirator selection
Hydrogen cyanide respirator selectionHCN
Manufacture of acrylonitrile/adiponitrile and other nitriles, electroplating, metal treatment, gold/silver extraction, and fumigation.
These are federal OSHA limits. The PEL shown is the federal OSHA value. About two dozen states run their own OSHA-approved plans, and some — notably California (Cal/OSHA) — enforce lower or additional exposure limits. If you work under a state plan, check your state's PEL and enter it as a custom limit in the calculator.
Cartridge (limited use): Gas-mask canister for HCN — ESCAPE ONLY; supplied-air/SCBA for work exposure
An APR fitted with the correct cartridge is only adequate up to its MUC (below) — the cartridge must be able to capture hydrogen cyanide. Rapidly fatal systemic asphyxiant with poor/unreliable warning at hazardous levels. NIOSH permits an air-purifying gas-mask canister for ESCAPE ONLY — NOT for routine work; supplied air or SCBA is required for any work in HCN. No ANSI K1 standard color band for a dedicated HCN cartridge. You must establish a change-out schedule; never rely on taste or smell. See the cartridge & filter guide.
⚠ Skin absorption hazard: a respirator alone is not enough
Hydrogen cyanide carries a NIOSH "skin" notation and is absorbed through the skin, so a respirator alone is not sufficient. Wear chemical-protective gloves and clothing rated for this substance, plus eye and face protection. Flame-resistant (FR) clothing guards against flash fire, not chemical permeation, so it is not a substitute for a chemical-protective suit.
⚠ Skin absorption hazard: a respirator alone is not enough
Hydrogen cyanide carries a NIOSH "skin" notation and is absorbed through the skin, so a respirator alone is not sufficient. Choose gloves and protective clothing rated against this chemical (check the Safety Data Sheet for permeation data), and use eye protection.
Calculator for Hydrogen cyanide
Result
Enter a concentration and an exposure limit to see the
compliant respirators and their Maximum Use Concentration.
Hazard ratio = concentration ÷ OEL · Minimum APF must meet or exceed it · MUC = APF × OEL (capped at IDLH). Source: OSHA 29 CFR 1910.134(d)(3)(i)(A), Table 1 — Assigned Protection Factors. Last verified 2026-07-16.
Maximum use concentration for Hydrogen cyanide by respirator
MUC = APF × the OSHA PEL (10 ppm), capped at the IDLH (50 ppm). Use this as a reference for the highest concentration each respirator class may be used at.
| Respirator | APF | MUC (ppm) |
|---|---|---|
| Air-Purifying Respirator · Quarter mask | 5 | 50 |
| Air-Purifying Respirator · Half mask | 10 | 50IDLH |
| Supplied-Air Respirator (Airline) · Half mask · Demand | 10 | 50IDLH |
| Self-Contained Breathing Apparatus · Half mask · Demand | 10 | 50IDLH |
| Powered Air-Purifying Respirator · Helmet / hood | 25 | 50IDLH |
| Powered Air-Purifying Respirator · Loose-fitting facepiece | 25 | 50IDLH |
| Supplied-Air Respirator (Airline) · Helmet / hood · Continuous flow | 25 | 50IDLH |
| Supplied-Air Respirator (Airline) · Loose-fitting facepiece · Continuous flow | 25 | 50IDLH |
| Air-Purifying Respirator · Full facepiece | 50 | 50IDLH |
| Powered Air-Purifying Respirator · Half mask | 50 | 50IDLH |
| Supplied-Air Respirator (Airline) · Full facepiece · Demand | 50 | 50IDLH |
| Supplied-Air Respirator (Airline) · Half mask · Continuous flow | 50 | 50IDLH |
| Supplied-Air Respirator (Airline) · Half mask · Pressure-demand / positive-pressure | 50 | 50IDLH |
| Self-Contained Breathing Apparatus · Full facepiece · Demand | 50 | 50IDLH |
| Powered Air-Purifying Respirator · Full facepiece | 1,000 | 50IDLH |
| Supplied-Air Respirator (Airline) · Full facepiece · Continuous flow | 1,000 | 50IDLH |
| Supplied-Air Respirator (Airline) · Full facepiece · Pressure-demand / positive-pressure | 1,000 | 50IDLH |
| Self-Contained Breathing Apparatus · Full facepiece · Pressure-demand / positive-pressure | 10,000 | 50IDLH |
Notes
NIOSH REL is a 4.7 ppm (5 mg/m3) [skin] short-term/ceiling limit (10-min), NOT an 8-hr TWA — label carefully. OSHA PEL TWA 10 ppm (11 mg/m3) [skin]. IDLH 50 ppm. Conversion 1 ppm = 1.10 mg/m3; MW 27.0. 'skin' = danger of skin absorption. (ACGIH TLV is 10 ppm Ceiling [skin] — not an OSHA/NIOSH value.)
Sources
- https://www.cdc.gov/niosh/npg/npgd0333.html
- https://www.cdc.gov/niosh/idlh/74908.html
- https://www.osha.gov/annotated-pels/table-z-1
Data confidence: high. Values are cited from OSHA and NIOSH but should be verified against the current source and a qualified professional before use. See how this works.