Aloha! Workers grinding Haliotis in Mexico are required to take "breather" breaks of 15min of every hour logged. A mask & particle filter is required. When I grind or sandblast it's in a blasting metal chamber with a wet/dry vac suction for sucking out the airborne elements. Any carbon-based particle elements are inheritantly bad for the lungs if no facial filtering mask is used. In the Philippines most shell "sweat shops" have grinders working all day. Haliotis from California and African Turbos are brought in by the container, cut and/or polished, & re-shipped to distributors. They use no mask & there's "white snow" created from years of grinding covering a huge area surrounding these work shops. If you have a small workshop just remember your goggles & mask. A external fan would be recommended too. Mahalo! CHRIS:) ---------------------------------------------------------------------- [log in to unmask] - a forum for informal discussions on molluscs To leave this list, click on the following web link: http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1 Type your email address and name in the appropriate box and click leave the list. ----------------------------------------------------------------------