CHC and Bristow in Norway issues a quite clever Emergency Breathing Device to their passengers.
It's a sort of "re-breather", just a mouthpiece attached to a hose that goes inside the drysuit. That way they breathe/rebreathe the air in the suit - and gives them some valuable extra time if they get submerged.
The CREW on the other hand doesn't get anything!
But we - of course - are machines!
And the crew on the "Los"-helicopters (Los=Harbour pilot) fly with personal emergency-bottles of air.