What is the difference scientifically between space heater versus forced air heating from a furnance

Space heaters causes my nose to become extremely stuffy. Is there any literature that supports the difference between space heater versus actual forced air heating from a furnance? We were told by Sears there is no difference. This really makes me sick almost like cold symptoms. It makes the room stuffy.

Well those symptoms sound like you're allergic to something. I wouldn't be surprised if the space heater was dusty and you're allergic to dust. Try getting one of those cans of compressed air for cleaning computers and spray out the space heater.