# Naphthalene diisocyanate — workplace exposure limit

For Naphthalene diisocyanate, niosh rel (ppm) is 0.005; niosh rel (mg/m³) is TWA 0.040; cas no. is 3173-72-6, verified against its source on 2026-09-08.

- **Substance:** Naphthalene diisocyanate _(verified: appears in its own passage below)_
- **CAS No.:** 3173-72-6 _(verified: appears in its own passage below)_
- **NIOSH REL (ppm):** 0.005 _(verified: appears in the quote below)_
- **NIOSH REL (mg/m³):** TWA 0.040 _(verified: appears in the quote below)_

## What the source says

> NIOSH REL TWA 0.040 mg/m3 (0.005 ppm) C 0.170 mg/m3 (0.020 ppm) [10-minute]

## Where each value comes from

This source states these in separate places, so each value is shown with the passage that states it.

### Substance

> CDC - NIOSH Pocket Guide to Chemical Hazards - Naphthalene diisocyanate

### CAS No.

> CAS No. 3173-72-6

## Source

- https://www.cdc.gov/niosh/npg/npgd0440.html

Last verified: 2026-09-08. Review by: 2027-09-08.
Part of [US workplace chemical exposure limits: federal OSHA, Cal/OSHA and NIOSH, side by side](https://referencesource.org/workplace-exposure-limits/).