# Phthalic anhydride — US workplace chemical exposure limits: federal OSHA vs Cal/OSHA, side by side

For Phthalic anhydride, cas no. is 85-44-9; pel (ppm) is 2; pel (mg/m³) is 12, verified against its source on 2026-08-05.

- **Substance:** Phthalic anhydride
- **CAS No.:** 85-44-9
- **PEL (ppm):** 2
- **PEL (mg/m³):** 12

## What the source says

> Phthalic anhydride | 85-44-9 | 2 | 12 | - |

## 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.

### PEL (ppm)

osha.gov says pel (ppm) is **2**, as of 2026-08-05.

> Phthalic anhydride | 85-44-9 | 2 | 12 | - |

Source: https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1

dir.ca.gov says pel (ppm) is **1**, as of 2026-08-05.

> 85449 | | Phthalic anhydride | 1 | 6

Source: https://www.dir.ca.gov/title8/5155.html


### PEL (mg/m³)

osha.gov says pel (mg/m³) is **12**, as of 2026-08-05.

> Phthalic anhydride | 85-44-9 | 2 | 12 | - |

Source: https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1

dir.ca.gov says pel (mg/m³) is **6**, as of 2026-08-05.

> 85449 | | Phthalic anhydride | 1 | 6

Source: https://www.dir.ca.gov/title8/5155.html


## Source

- https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1000TableZ1
- https://www.dir.ca.gov/title8/5155.html

Last verified: 2026-08-05. Review by: 2027-08-05.
Part of [US workplace chemical exposure limits: federal OSHA vs Cal/OSHA, side by side](https://referencesource.org/workplace-exposure-limits/).