Pennsylvania Code
Title 25 - ENVIRONMENTAL PROTECTION
Part I - Department of Environmental Protection
Subpart D - Environmental Health and Safety
Article IV - Occupational Health and Safety
Chapter 207 - NONCOAL UNDERGROUND MINES
Subchapter C - MINED-OUT AREAS
GENERAL PROVISIONS
Section 207.302 - Definitions

The following words and terms, when used in this subchapter, have the following meanings, unless the context clearly indicates otherwise:

Outside air-Air moving through the mined-out passageways after entering them through the main or accessory portals by mechanical or natural forces.

Pure air-Air containing not less than 19.5% oxygen, not more than 0.5% carbon dioxide and no harmful quantities of other noxious or poisonous gases, dust, soot or particulates.

Safety container-A container not over 5 gallons capacity, having a spring closing lid and spout cover.