Sorry.. They used sand to blast my engine block yesterday morning. They also still use it more then glass bead, coconut shell and soda. Its cheaper! Safety measures such as full body suits and air supplied from tanks are used. As for silicosis do you have any idea how much exposure you need? Its not something you'll need to worry about and you should really be using some type of quality filter or supplied fresh air anyways (not a paper mask). All media gives off a dust and NONE of it is good for you once in your lungs. Also 'much better abrasives' entirely depends on what results your looking for. Soda is useless against rust and scale yet sand will remove it. Personally I wanted to remove the 3 layers of paint, original primer AND the rust in one go.

4reboy is correct on the warpage issue. Care is obviously needed but with constant movement and a good angle your panels shouldn't warp at all. Note also that chemical dipping has been banned in many areas because of environmental issues and cleanup so its not always an option.

Not one panel was warped or rippled from when we wet sand blasted our car last year and I'd never done it before. With a gas powered pressure washer, a sand blast attachment, a buck and a lot of sand you don't really have to worry about warpage since the cold water from your garden hose keeps everything cool. I tested this on our drivers quarter since I knew it needed to be replaced and I'd have cut holes through the panel before warping it.