While screwing in an electrical cover in my new home (built in 1919) I noticed these fibers sticking out of the plaster or skim coat. I have not seen these anywhere else. Hope the picture loads. Are these asbestos fibers?
Often, people talk about “old-fashioned horse-hair plaster,” but the binding agent in old plaster walls was more commonly cattle hair. -searshomes.org
I am reasonably sure it's not asbestos.