In US regulations asbestos-containing material is a material that has more than one percent (1 %) asbestos by weight.
An asbestos square is a square of a material that contains asbestos in it.
Asbestos is a porous material and can absorb water.
Asbestos (particularly blue asbestos)
Items with greater than 1 percent of asbestos minerals are considered to contain asbestos.
Asbestos cement
An asbestos-containing material is one that has a detectable percentage of asbestos fibres, which is usually more than 0,1 %.
Friable asbestos is material that contains asbestos fibers and that can be crumbled into dust in the hand without the use of tools.
Chrysotile is a form of asbestos accounting for about 95 percent found in the United States. It is a soft, fibrous silicate material. Chrysotile and other forms of asbestos are considered to be hazardous.
Asbestos cement
Asbestos is catergorised as a Type 1 carcinogen, (possitive effect on humans)
Asbestos removal is only really necessary if the material is beyond repair or prior to demolition or refurbishment. Any asbestos containing material that is in a good condition should be managed to ensure there is no fibre release.
Anything items covered with asbestos material are dangerous. But when the items covered with asbestos -- tiles, ductwork, edging, joint connectors on ductwork-- become cracked, the asbestos dust is especially dangerous. Or, when contractors demolish or renovate a building containing asbestos, it will get in the air.