30 CFR § 60.2 - Definitions.

---
identifier: "/us/cfr/t30/s60.2"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "30 CFR § 60.2 - Definitions."
title_number: 30
title_name: "Mineral Resources"
section_number: "60.2"
section_name: "Definitions."
chapter_name: "MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR"
subchapter_number: "M"
subchapter_name: "UNIFORM MINE HEALTH REGULATIONS"
part_number: "60"
part_name: "RESPIRABLE CRYSTALLINE SILICA"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "30 U.S.C. 811, 813(h) and 957."
regulatory_source: "89 FR 28470, Apr. 18, 2024, unless otherwise noted."
cfr_part: "60"
---


# 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
<sup>3</sup>) 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.