I'm no expert on this but many years ago I worked for a school district. There is a lot of asbestos in the old buildings. The key was always whether the asbestos was "friable" (I think that was the term). If it was painted over or contained in a sealed product, it was considered safe as no particles were entering the air. If it wasn't completely covered or contained it was friable and could be air born. I'm not sure this helps, but thought I'd volunteer what I know. Another example... we have a very old boiler in our house which has an asbestos covering. The asbestos is covered by another cover. According to the heating people, it is no problem as is. If we ever need to remove it, that's another story.