---
kind: "section"
citation: "30 C.F.R. § 60.2"
title: "30"
number: "60.2"
heading: "Definitions."
url: "https://uscodex.org/cfr/30/60.2"
---

# §60.2. Definitions.


The following definitions apply in this part:

Action level means an airborne concentration of respirable crystalline silica of 25 micrograms per cubic meter of air (µg/m 3) for a full-shift exposure, calculated as an 8-hour time-weighted average (TWA).

Respirable crystalline silica means quartz, cristobalite, and/or tridymite contained in airborne particles that are determined to be respirable by a sampling device designed to meet the characteristics for respirable-particle-size-selective samplers that conform to the International Organization for Standardization (ISO) 7708:1995: Air Quality—Particle Size Fraction Definitions for Health-Related Sampling.

Specialist means an American Board-Certified Specialist in Pulmonary Disease or an American Board-Certified Specialist in Occupational Medicine.


## Notes

### Authority

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

### Source

Source: 89 FR 28470, Apr. 18, 2024, unless otherwise noted.