Considering purchasing a sand blaster but confused about types of sand which can be used. Can you use the type of sand from a building supply and/or "play sand". Have heard that breathing silica sand is bad for health and I'm wondering if these types of sand would be any better, health-wise and efficiency-wise. I'm going to be working in an open (non-enclosed) area and need something which will be cost-efficient and environmentally friendly. (Note: I am wanting to remove rust from sheet metal on old tractor.)