Hi, John -
In the "Olden Days", asbestos was used as the insulation around the boiler - about 4 inches worth -
and at least some of it had to be removed and replaced every time a few staybolts were replaced.
IIRC, a full boiler inspection meant that ALL the jacketing and insulation had to be removed and later replaced, so someone working in a railroad backshop would be exposed to a lot more loose asbestos and airborn fine particles - the main cause of lung problems - than would someone working with asbestos gasgets, etc. Even a locomotive assembly plant like Alco or Lima would probably have more asbestos dust in the air than any automobile shop.
- Russo