Permissible Exposure Limit (PEL)
An Occupational Safety and Health Administration (OSHA) allowable exposure level in workplace air averaged over an 8-hour shift of a 40 hour workweek.

Anthophyllite
A type of asbestos in the amphibole group; it is also known as azbolen asbestos.

Class IV asbestos work
Means maintenance and custodial activities during which employees contact but do not disturb ACM or PACM and activities to clean up dust, waste and debris resulting from Class I, II, and III activities.

RACM
Regulated Asbestos-Containing Material is (a) friable asbestos material, (b) Category I non-friable ACM that has become friable, (c) Category I non-friable ACM that will be or has been subjected to sanding, grinding, cutting or abrading, or (d) Category II non-friable ACM that has a high probability of becoming or has become crumbled, pulverized, or reduced to powder by the forces expected to act on the material in the course of demolition or renovation operations.

Excursion Limit (EL)
1 Fiber per cubic centimeter averaged over a 30 minute sampling period.

Fibrosis
A condition marked by the increase of connective, fibrous tissue.

Chrysotile Asbestos
A fibrous member of the serpentine group of minerals. Chrysotile asbestos fibers are flexible and have a curved morphology. It is the most common form of asbestos used commercially, also referred to as white asbestos.

Minimal Risk Level (MRL)
An estimate of daily human exposure to a hazardous substance that is likely to be without an appreciable risk of adverse noncancer health effects over a specified route and duration of exposure.

Recommended Exposure Limit (REL)
A National Institute for Occupational Safety and Health (NIOSH) time-weighted average (TWA) concentrations for up to a 10-hour workday during a 40-hour workweek.

Stage 3 Mesothelioma
Stage 3 mesothelioma has spread to the chest wall, food pipe (oesophagus) or lymph nodes on the same side of the chest