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.

Friable asbestos
Any material containing more than one percent asbestos, and that can be crumbled or reduced to powder by hand pressure. (May include previously non-friable material which becomes broken or damaged by mechanical force.)

Bulk Sample
A sample of suspected asbestos-containing material that is obtained from a building to be analyzed microscopically for asbestos content. Bulk sample analysis can be part of a process to assess the hazard from asbestos in a building.

Immediately Dangerous to Life or Health (IDLH)
The maximum environmental concentration of a contaminant from which one could escape within 30 minutes without any escape-impairing symptoms or irreversible health effects.

Actinolite
One of the six types of asbestos.

Laparotomy
Abdominal exploration is a type of surgery where the abdomen is opened (laparotomy) and explored (exploratory laparotomy) for examination and treatment of problems. Might be used in relation to asbestos disease problems.

Malignant pleural mesothelioma
Malignant pleural mesothelioma is a type of cancer that affects the inside lining of the chest cavity. It is usually associated with asbestos exposure.

Tremolite
Tremolite may occur in fibrous form (an asbestos). It is not used commercially in the United States, but is a common impurity in chrysotile asbestos and vermiculite mined from deposits in Libby, Montana.

Serpentine
In the asbestos varieties, the brucite and silicate layers bend into tubers that produce the fibers. Chrysotile asbestos is a fibrous member of the serpentine group. "Serpentine" comes from mottled shades of green on massive varieties, suggestive of snake markings.

Intermediate Exposure
Exposure to a chemical for a duration of 15-364 days, as specified in the Toxicological Profiles.