I wonder if the CO monitor is actually meant to be a CO2 monitor? Lots of hot bodies dancing in a club will give off a lot of CO2 and create a "stale air" effect. A CO2 monitor might be intended to ramp up the ventilation if the atmosphere inside the club got too stale.
I've seen CO2 monitors/controls installed on HVAC systems in meeting rooms for the same reason...if the atmosphere gets stuffy with everybody breathing out CO2, then the system ramps up and brings in more outside air, to freshen up the room.
