Carbon Dioxide

Carbon Dioxide Sensor CO2 detection is designed to deal with its production either via cooking or biological processes (namely breathing).  
CO2 is roughly equal weight and density as air it will therefore naturally diffuse equally within a space.
CO2 detectors are for the purpose of monitoring the air quality within an area to ensure adequate ventilation is taking place, as such the detectors should be located with the main body of the room within the “breathing zone” (4 to 8 feet) but not in such a place they'd likely be exposed to a potential release point (i.e. someone breathing on it).