Polyurethane pooled in all the heat vents

Q: Due to a hardwood refinishing job w/ improper preparation my entire home has polyurethane pooled in all the heat vents. What are the health concerns and how do I remove it?

A: There shouldn’t be any health concerns. Once the finish is hardened the mineral spirit solvent has left the film. I would probably use a chisel, sharp knife or some type of scraper to remove the finish from off the pipe.