Asbestos is a mineral that has been mined, processed and manufactured into heat resistant items and used as insulation.  It has been used in exterior construction panels and shingles on buildings, in some types of flooring products, automotive brake shoes, and many different things.  One of the charactistics of it is that it breaks into smaller fibers.  These fibers can have a "hook" on the end, and when breathed in, can lodge in the lung, causing asbestosis.  Asbestos can also enter the body in other ways, and have other catastrophic results.  The result is a horrible disease know as Mesotheilioma.

Since sometime before WWI, into the 1980's, asbestos has been used as insulation for many kinds of boilers, including marine boilers onboard Naval ships. Sailors who have worked operating or maintaining the boilers and downstream equipment onboard as well as others may have been exposed to these fibers.  Use has not been necessarily confined to Naval vessels.  Anywhere a need has existed for insulating something very efficiently, asbestos may have been used.  Today, other materials are substituted. 

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