In general, maintenance staff working on rooftop fume ho od exhaust equipment have indicated their concerns about being on a roof, and possibly being exposed to whatever is being vented. 

In a more specific laboratory situation, involving MOCVD (metal organic chemical vapor deposition), we have a lock-out tag-out polic y, due to the severity of the toxic gases involved.

Questions:

1. Does anyone else have MOCVD labs, and to what exten t are controls in place for protection of workers on roof tops?
2. Does anyone else employ a LOTO policy?   
3. Are roof tops key-accessible only?