Methanol (67-56-1)
Methanol is a volatile organic compound with CAS Registry Number 67-56-1. Under the OSHA air contaminants standard (29 CFR 1910.1000), its Permissible Exposure Limit (PEL) — the legal 8-hour time-weighted average (TWA) for general industry — is 200 ppm. The principal target organs are the CNS; optic nerve, and workplace air is sampled and analyzed by NIOSH 2000.
Exposure Limits at a Glance
| Limit | Value | Basis |
|---|---|---|
| OSHA PEL (8-hr TWA) | 200 ppm | 29 CFR 1910.1000 |
| NIOSH REL | See note below | NIOSH Pocket Guide |
| Hazard Class | Volatile Organic Compound | VOC |
| Target Organs | CNS; optic nerve | NIOSH / OSHA |
| Sampling Method | NIOSH 2000 | NIOSH Manual of Analytical Methods |
NIOSH REL note: TWA values in the ppm range; NIOSH RELs are frequently 10x stricter than the OSHA PEL. The REL is a non-regulatory recommendation; where a NIOSH REL exists it is typically more protective than the OSHA PEL.
How It Enters the Body & Health Effects
Exposure to Methanol is assessed against the CNS; optic nerve — the organ systems most consistently affected in occupational studies. Employers must ensure no employee’s 8-hour TWA exceeds the 200 ppm PEL, and must use engineering controls, work practices, and — where required — respiratory protection to keep exposures at or below that level.
- Hazard class: Volatile Organic Compound. VOC-class agents are managed with the hierarchy of controls (elimination, substitution, engineering controls, administrative controls, then PPE).
- Monitoring: collect personal air samples in the breathing zone and submit them under NIOSH 2000 for laboratory analysis.
- Medical surveillance: consult the OSHA substance-specific standards and the NIOSH Pocket Guide when the target organs are the CNS; optic nerve.
Sampling & Compliance Notes
- Determine whether the exposure is a full-period 8-hour TWA or a short-term / ceiling scenario. Ceiling and STEL excursions apply to several VOC-class agents regardless of the 8-hour average.
- Calibrate personal sampling pumps before and after each shift and record flow rates; method NIOSH 2000 specifies media, flow, and analysis.
- Compare analytical results to the OSHA PEL of 200 ppm and the NIOSH REL. Document the higher of the two for internal exposure-control targets.
- Where the PEL includes a “skin” notation, dermal absorption can contribute to the dose — glove selection and hygiene facilities are part of compliance.
Frequently Asked Questions
What is the OSHA PEL for Methanol?
The OSHA Permissible Exposure Limit (8-hour TWA) for Methanol is 200 ppm.
What is the CAS number for Methanol?
The CAS Registry Number for Methanol is 67-56-1.
What are the target organs for Methanol?
The primary target organs are the CNS; optic nerve.
How do you measure Methanol in workplace air?
Use NIOSH analytical method NIOSH 2000 for air sampling and laboratory analysis.
What hazard class is Methanol?
It is classified here as a Volatile Organic Compound (VOC).