At a glance
| Chemical family | Ketone — four-carbon aliphatic ketone (2-butanone / methyl ethyl ketone) |
| CAS number | 78-93-3 |
| Classification | Not classified by IARC. EPA delisted from Clean Air Act HAP list (2005). WHO air quality guidelines do not set a specific limit. Neurotoxic at high occupational exposures. Low concern at typical indoor levels |
| Where you encounter it | Adhesives and contact cements; paints, varnishes, and lacquers; printing inks; cleaning solvents; new furniture finishes; indoor air from renovation activities |
| Sleep micro-environment relevance | Present in bedroom air after renovation activities (painting, furniture finishing, adhesive use). Dissipates rapidly due to high volatility. Transient rather than chronic bedroom exposure |
Regulatory & certification status
| European Union | REACH registered substance. CLP Eye Irrit. 2 (H319), STOT SE 3 (H336 — may cause drowsiness or dizziness). EU OEL: 200 mg/m3 (TWA) for occupational settings. Regulatory |
| United States | EPA delisted from Clean Air Act HAP list (2005). OSHA PEL: 200 ppm (TWA). NIOSH REL: 200 ppm (TWA). ACGIH TLV: 200 ppm. Regulatory |
| Canada | Occupational exposure limits set by provincial regulators. No Health Canada indoor air quality guideline. Regulatory |
| International | Not IARC classified. EPA HAP delisted (2005). WHO does not set specific indoor air quality guidelines for MEK. Widely considered lower concern than other common solvents. Regulatory |
What it is
Methyl ethyl ketone is a four-carbon ketone (CH3COCH2CH3) used extensively as a solvent in industrial and consumer applications. It is an effective solvent for a wide range of coatings, adhesives, and polymers. MEK has a sweet, sharp odour detectable at relatively low concentrations. IARC has not evaluated MEK for carcinogenicity — available evidence does not suggest carcinogenic activity. The primary toxicological concern is central nervous system depression and peripheral neuropathy at high occupational exposures. Importantly, MEK potentiates the neurotoxicity of n-hexane — co-exposure to MEK and n-hexane produces worse neuropathy than n-hexane alone. The EPA delisted MEK from the Clean Air Act hazardous air pollutant list in 2005, concluding that it posed lower risk than other listed solvents.
Where it shows up in bedding
MEK is not a bedding ingredient. It enters the bedroom as a transient VOC from renovation and furnishing activities: fresh paint, new varnish or lacquer on furniture, adhesives used in flooring installation, and contact cements. MEK has high vapour pressure (78 mmHg at 20C) and evaporates rapidly — indoor air concentrations spike during and immediately after application but decline quickly with ventilation. For the sleep environment, the concern is limited to the first few days after painting a bedroom or introducing newly finished furniture. Ventilating the bedroom during and after these activities is the standard recommendation. MEK does not persist in indoor environments the way semi-volatile compounds like phthalates or flame retardants do.
Citations
- EPA (2005). Revision to the List of Hazardous Air Pollutants — Removal of Methyl Ethyl Ketone (MEK). Federal Register 70 FR 75047. Source Regulatory
- ATSDR (1992). Toxicological Profile for 2-Butanone. Source Regulatory
- ECHA. 2-Butanone — Substance Information. Source Regulatory
Frequently asked questions
Is MEK dangerous in a freshly painted bedroom?
At the concentrations present during and shortly after painting, MEK can cause eye irritation, headache, and drowsiness. These are temporary effects that resolve when you leave the area or ventilate the room. MEK evaporates rapidly, so indoor air concentrations drop quickly with good ventilation. Wait until the paint smell has dissipated before sleeping in a freshly painted bedroom — typically 24-48 hours with windows open.
Is MEK a carcinogen?
No. IARC has not classified MEK as a carcinogen, and available evidence does not suggest carcinogenic activity. The EPA delisted MEK from the Clean Air Act hazardous air pollutant list in 2005, concluding it was less hazardous than other listed solvents. The primary concern with MEK is acute central nervous system effects (drowsiness, dizziness) at high occupational exposures, not chronic cancer risk.
Related compounds
Embr is a sleep environment company researching and addressing the chemistry of the bedroom. Research and product development in progress.
Last reviewed 2026-07-08. If you find a factual error, contact us.