Asbestos or not?

[larry sarlo]

I cut into my floor doing some plumbing repairs. I noticed a fibros board under the underlayment.

The fibros board covers over my return ducts to encapsulate the returns thru floor joists. I appears to be under the entire floor underlayment also which is a crawl space.

Obviously i have already been contaminated if it is asbestos... What do i do if it is asbestos? IS it asbestos? Can you tell by pictures?

Im particularly worried since it is in my hvac ventilation system already