Naphthalene — workplace exposure limit
What is the pel (ppm) for Naphthalene — workplace exposure limit?
For Naphthalene, pel (ppm) is 10; pel (mg/m³) is 50; cas no. is 91-20-3, verified against its source on 2026-08-05.
Naphthalene | 91-20-3 | 10 | 50 | - |
— osha.gov, retrieved 2026-08-05
10
The most of this substance workplace air may legally contain, averaged over an 8-hour shift — OSHA's permissible exposure limit (PEL), in parts per million, from the agency's own table row quoted below. Where federal OSHA and Cal/OSHA disagree, both limits are stated, each with its own agency's table row as evidence. NIOSH's number, where there is one, is shown separately: it is a recommended limit, not a legal one, and it is often the strictest of the three.
- Substance
- Naphthalene verified
- CAS No.
- 91-20-3 verified
- PEL (ppm)
- 10 verified
- PEL (mg/m³)
- 50 verified
- NIOSH REL (ppm)
- TWA 10 per cdc.gov
- NIOSH REL (mg/m³)
- 50 per cdc.gov
What cdc.gov says
NIOSH REL TWA 10 ppm (50 mg/m3) ST 15 ppm (75 mg/m3)
— cdc.gov, retrieved 2026-09-08
Sources disagree
More than one authority states this, and they do not state the same thing. Both are reproduced with the source each came from — deciding between them is yours, not ours.
PEL (ppm)
osha.gov says pel (ppm) is 10, as of 2026-08-05.
Naphthalene | 91-20-3 | 10 | 50 | - |
https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1
dir.ca.gov says pel (ppm) is 0.1, as of 2026-08-05.
91203 | S | Naphthalene | 0.1 | 0.5
https://www.dir.ca.gov/title8/5155.html
PEL (mg/m³)
osha.gov says pel (mg/m³) is 50, as of 2026-08-05.
Naphthalene | 91-20-3 | 10 | 50 | - |
https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1
dir.ca.gov says pel (mg/m³) is 0.5, as of 2026-08-05.
91203 | S | Naphthalene | 0.1 | 0.5
Sources
- osha.govhttps://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1
- dir.ca.govhttps://www.dir.ca.gov/title8/5155.html
- cdc.govhttps://www.cdc.gov/niosh/npg/npgd0439.html