If you're worried about asbestos, check out he
http://www.epa.gov/asbestos/

Can you coat over it? Many times, as you might see on the EPA site,
the best way to deal with asbestos is to leave it in place if it's not
something that'll be disturbed. Maybe you could carefully coat over
it:

I had some luck making a stippled ceiling in a small area with some
drywall mud mixed with white ceiling paint. Apply the mud to the
ceiling in a moderate coat (maybe 1/8" thick or so). Take a stipple
brush (or in one case I used a push-broom head) and press the bristles
into the mud and pull back out. It'll look rather sharp and spikey,
but you can leave it and knock it down a little later - once the mud is
somewhat dry, you can take a wide putty knife or scraper and knock off
as much or as little of the spikes as you like, leaving behind a
finished texture. The wetter it is when you scrape it the more
"leather-like" and flat it'll be after scraping.