Nitrogen saturation as a permanent condition

If people are under permanent increased pressure, their blood will take in more nitrogen from the air. Should divers accend too quickly to the surface, this gas would bubble out, just like CO2 from a can of soda. That's why divers who spend a long time under water need a long time to get back to the surface - and it's also why they prefer to remain in a pressurized environment and avoid surfacing.