Respirator selection
Hydrogen cyanide respirator selectionHCN
Manufacture of acrylonitrile/adiponitrile and other nitriles, electroplating, metal treatment, gold/silver extraction, and fumigation.
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.