---
kind: "section"
citation: "30 C.F.R. § 90.100"
title: "30"
number: "90.100"
heading: "Respirable dust standard."
url: "https://uscodex.org/cfr/30/90.100"
---

# §90.100. Respirable dust standard.


The following is required as of April 14, 2025. After the 20th calendar day following receipt of notification from MSHA that a [part 90](/cfr/30/part90.md) miner is employed at the mine, the operator shall continuously maintain the average concentration of respirable dust in the mine atmosphere during each shift to which the [part 90](/cfr/30/part90.md) miner in the active workings of the mine is exposed, as measured with an approved sampling device and expressed in terms of an equivalent concentration, at or below 0.5 mg/m 3.


## Notes

### Amendments

[89 FR 28482, Apr. 18, 2024]

### Source

Source: 79 FR 24989, May 1, 2014, unless otherwise noted.

### Authority

Authority: 30 U.S.C. 811, 813(h), 957.

### Source

Source: 45 FR 80769, Dec. 5, 1980, unless otherwise noted.

### Amendments

[89 FR 28482, Apr. 18, 2024]