I'm starting interior renovations on a circa 1900 home in Pennsylvania - including some replacements to plaster wall areas that are crumbling here and there. I was so excited by the great advise and how-to's here on this site. I was sharing this with a mechanical engineer who I work with and he said wait ... make sure there's no asbestos in that plaster! My heart sank. I'm a 47 year old woman with zero home renovation skills. I know at some point I'll have to have asbestos removed (contained) on some basement piping, but in the walls???? Is this true? How to I ascertain if there's asbestos in the walls? Thank you so very much.