Respirator selection
Carbon dioxide respirator selectionCO2
Welding shielding gas, beverage carbonation, dry ice, and fire suppression; a confined-space asphyxiation hazard.
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.
⚠ Air-purifying respirators are NOT permitted
A supplied-air respirator (SAR) or SCBA is required for carbon dioxide. An APF/MUC figure does not make an air-purifying respirator acceptable here. SIMPLE ASPHYXIANT — no air-purifying cartridge can remove CO2 or replace displaced oxygen. NIOSH lists only supplied-air respirators and SCBA. Air-purifying respirators are never acceptable. See the cartridge & filter guide.
Calculator for Carbon dioxide
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 Carbon dioxide by respirator
MUC = APF × the OSHA PEL (5,000 ppm), capped at the IDLH (40,000 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 | 25,000 |
| Air-Purifying Respirator · Half mask | 10 | 40,000IDLH |
| Supplied-Air Respirator (Airline) · Half mask · Demand | 10 | 40,000IDLH |
| Self-Contained Breathing Apparatus · Half mask · Demand | 10 | 40,000IDLH |
| Powered Air-Purifying Respirator · Helmet / hood | 25 | 40,000IDLH |
| Powered Air-Purifying Respirator · Loose-fitting facepiece | 25 | 40,000IDLH |
| Supplied-Air Respirator (Airline) · Helmet / hood · Continuous flow | 25 | 40,000IDLH |
| Supplied-Air Respirator (Airline) · Loose-fitting facepiece · Continuous flow | 25 | 40,000IDLH |
| Air-Purifying Respirator · Full facepiece | 50 | 40,000IDLH |
| Powered Air-Purifying Respirator · Half mask | 50 | 40,000IDLH |
| Supplied-Air Respirator (Airline) · Full facepiece · Demand | 50 | 40,000IDLH |
| Supplied-Air Respirator (Airline) · Half mask · Continuous flow | 50 | 40,000IDLH |
| Supplied-Air Respirator (Airline) · Half mask · Pressure-demand / positive-pressure | 50 | 40,000IDLH |
| Self-Contained Breathing Apparatus · Full facepiece · Demand | 50 | 40,000IDLH |
| Powered Air-Purifying Respirator · Full facepiece | 1,000 | 40,000IDLH |
| Supplied-Air Respirator (Airline) · Full facepiece · Continuous flow | 1,000 | 40,000IDLH |
| Supplied-Air Respirator (Airline) · Full facepiece · Pressure-demand / positive-pressure | 1,000 | 40,000IDLH |
| Self-Contained Breathing Apparatus · Full facepiece · Pressure-demand / positive-pressure | 10,000 | 40,000IDLH |
Notes
NIOSH REL TWA 5,000 ppm, ST 30,000 ppm. OSHA PEL TWA 5,000 ppm (Table Z-1). IDLH 40,000 ppm (4%). NPG conversion 1 ppm = 1.80 mg/m3; MW 44.0.
Sources
- https://www.cdc.gov/niosh/npg/npgd0103.html
- https://www.cdc.gov/niosh/idlh/124389.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.