Safety n eeds to be applied equally and consistently.  Loose clothing or clothi ng that obscures peripheral vision in a chemistry laboratory (or machine sh op - think Yale) is a safety hazard and is not acceptable.  Safety is agnostic.

 < /o:p>

The real issue here is whether you r institution is willing or required to make some sort of accommodation suc h as permitting the student to do her lab time without the burka when only females are around.  And that answer will obviously vary from state to state.

You should immediately consult your college 's legal counsel **in writing**, and be sure to impress on them from the st art that safety can not be compromised under any circumstances.  You w ill no doubt want to come up with a standard written policy to address this issue.

Rob Toreki