in this case is was residual and nothing. they paid 20k to have it remediated and i think 25k for the roof leak that caused it. i’m just repairing the damage inside. since it was inside a school, and the one my daughter attends, i took a sample and had it tested. it was nothing. if it doesn’t reappear, it is confirmed to be nothing and has been remediated, if not, servepro comes back and does it right this time. thanx for the link, good info in there.