Respirator selection
Methyl ethyl ketone (2-Butanone, MEK) respirator selectionCH3COCH2CH3 (C4H8O)
Solvent in paints, coatings, adhesives, printing inks, and lacquers; degreasing and resin/rubber processing.
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.
Recommended cartridge: Organic Vapor (OV) — Black band
An APR fitted with the correct cartridge is only adequate up to its MUC (below) — the cartridge must be able to capture methyl ethyl ketone (2-butanone, mek). Standard OV cartridge effective up to the MUC; adequate odor warning. High volatility shortens service life somewhat. IDLH 3000 ppm. You must establish a change-out schedule; never rely on taste or smell. See the cartridge & filter guide.
Calculator for Methyl ethyl ketone (2-Butanone, MEK)
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 Methyl ethyl ketone (2-Butanone, MEK) by respirator
MUC = APF × the OSHA PEL (200 ppm), capped at the IDLH (3,000 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 | 1,000 |
| Air-Purifying Respirator · Half mask | 10 | 2,000 |
| Supplied-Air Respirator (Airline) · Half mask · Demand | 10 | 2,000 |
| Self-Contained Breathing Apparatus · Half mask · Demand | 10 | 2,000 |
| Powered Air-Purifying Respirator · Helmet / hood | 25 | 3,000IDLH |
| Powered Air-Purifying Respirator · Loose-fitting facepiece | 25 | 3,000IDLH |
| Supplied-Air Respirator (Airline) · Helmet / hood · Continuous flow | 25 | 3,000IDLH |
| Supplied-Air Respirator (Airline) · Loose-fitting facepiece · Continuous flow | 25 | 3,000IDLH |
| Air-Purifying Respirator · Full facepiece | 50 | 3,000IDLH |
| Powered Air-Purifying Respirator · Half mask | 50 | 3,000IDLH |
| Supplied-Air Respirator (Airline) · Full facepiece · Demand | 50 | 3,000IDLH |
| Supplied-Air Respirator (Airline) · Half mask · Continuous flow | 50 | 3,000IDLH |
| Supplied-Air Respirator (Airline) · Half mask · Pressure-demand / positive-pressure | 50 | 3,000IDLH |
| Self-Contained Breathing Apparatus · Full facepiece · Demand | 50 | 3,000IDLH |
| Powered Air-Purifying Respirator · Full facepiece | 1,000 | 3,000IDLH |
| Supplied-Air Respirator (Airline) · Full facepiece · Continuous flow | 1,000 | 3,000IDLH |
| Supplied-Air Respirator (Airline) · Full facepiece · Pressure-demand / positive-pressure | 1,000 | 3,000IDLH |
| Self-Contained Breathing Apparatus · Full facepiece · Pressure-demand / positive-pressure | 10,000 | 3,000IDLH |
Notes
NIOSH REL TWA 200 ppm (590 mg/m3) AND STEL 300 ppm (885 mg/m3). OSHA PEL TWA 200 ppm (590 mg/m3). IDLH 3,000 ppm. Conversion 1 ppm = 2.95 mg/m3; MW 72.1.
Sources
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.