Comment by varenc

The only risk is that the O2 levels drop too low from a massive release of He...and while I'll 100% agree this is a very minor risk, I'd still rather hospitals play it safe and install O2 deficiency monitors.

The article I linked mentioned that O2 monitors are legally required for hospitals in NYC. That regulation might have been created because in 2000 someone working on an MRI machine died from a Nitrogen leak (it's also used for cooling and like He, the only risk is that it displaces O2). It's likely this person wouldn't have died if an O2 monitor was in place that sounded an alarm fast enough for the victims to leave the area. http://www.nydailynews.com/archives/news/nitrogen-gas-leak-k...

edit: googling a bit more found some interesting references on dealing with "oxygen-displacing gases". O2 monitors are on the long list recommendations/requirements. One thing I found interesting is that at one laboratory part initial assessment involves a controlled release of the maximum amount of gas that will be stored and then measuring the drop in O2.

https://www.ors.od.nih.gov/sr/dohs/Documents/ProtocolOxygenM...

http://www-group.slac.stanford.edu/esh/eshmanual/references/...