Previous responses were very helpful and I have very little to add but only reinforce:

·         Rooftops and facility areas such as boiler and chiller rooms, electrical switch gear rooms, elevator penthouses, and telephone and computer rooms should be restricted.

·         Maintenance should be coordinated with building tenants.

·         It may be worthwhile to conduct chemical monitoring in the area to determine the concentration of the metal organic vapor in the area where the workers have the potential of exposure.

·         Someday building occupants, neighbors or the community will want to know what is being released or re-entering the building and what their potential exposure could be.  Here tracer gas studies should provide an indication.  Be prepared. 

·         Regarding the lock out/tag out policy while I do not have any experience with the situation described it seems that if the system is shut down then the same policy should apply to the labs.

In general, maintenance staff working on rooftop fume hood 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 policy, due to the severity of the toxic gases involved.

Questions:

1. Does anyone else have MOCVD labs, and to what extent 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?

Thanks for the feedback.

-Stefan Wawzyniecki, CIH, CHMM

 Univers ity of Connecticut