Alan, the clay dust is thick in the air like fog! And not only is it just clay, it is clay with bleach, Caustic, and half a dozen other chemicals in it!
Sometimes we wear a mask, some areas we don't need to. It is certainly a dangerous concoction floating around the work space. But fortunately where I press the wet clay (which is 75% of my job) is totally dust free. Just slushy under foot