Wear some protective gear, idiot!
While the body's osteoclasts can break down even glass fibers, some of this stuff is biopersistent and will remain in your body.
I'd be more worried about dust from bat and rodent shit in attics. Really great stuff to inhale, full of highly pathogenic bacteria, viruses and fungi. I think you have Hantavirus in California.
When we were working in the tropics they had locals renovate the roof of some facility building. It was full of bats. 3 workers ended up in hospital, dunno if they made it. Afterwards people in hazmat suits tore down the entire roof. Really nasty stuff. Makes me glad we have none of this here. And no fiberglass in the attic either.