Annoying beeping gas detector (atmos analyzer revamp)

[rulib]

In real life, people working around hazardous gases rely on annoying beeping devices to detect low oxygen, high CO2, etc. I think that the atmos analyzer and any PDA versions thereof should be retooled so that you can set it up to alarm if it detects a hazardous atmosphere. Thus allowing CO2 detection especially, for the paranoid. Also would alert you as to stuff going wrong with the air if you were wearing internals and wouldn't notice it the hard way.

http://www.safelincs.co.uk/gas-alert-micro-clip-xt/ This is a typical unit in real life.