Asbestos pipe insulation. Proper PPE when crawling the crawl space is important

Asbestos is a set of six naturally occurring silicate minerals, chrysotile, crocidolite, amosite, anthophyllite, tremolite, and actinolite. Among these, chrysotile and amosite asbestos are the most common. All six minerals are now known to be carcinogenic to humans.

Asbestos mining has been around for a while starting about 4,000 years ago. Approximately three million workers in the United States are estimated to be exposed to silica, man-made mineral fibers, and asbestos. The lung is the primary target organ of concern.

Information on Asbestos in the Home
http://www.cpsc.gov/en/Safety-Education/Safety-Guides/Home/Asbestos-In-The-Home/