My understanding of the burning or combustion of paraffin, yields no Carbon Monoxide - here is the equation: C25H52 & 39 O2 --> 25 CO2 & 28 H2O which means 39 molecules of Oxygen combines with so much paraffin to release 25 molecules of Carbon Dioxide (CO2) and 28 molecules of Water (H2O) - there is no Carbon Monoxide.
However, incomplete burning can and does occur, which can result in Carbon Monoxide of varying levels. (Which have sadly led to some deaths, as publicised in the media.)
I consider a Carbon Monoxide sensor alarm to be an essential part of any indoor living space including where grow rooms are situated. As it costs only pocket-money to buy there really is no reason not to have one. In a closed grow situation then an alarm is necessary inside the grow area.
However, CO2 monitors are very expensive and one needs to be careful not to overdo the CO2 levels, although if you get an infestation of bugs, very high levels of CO2 short term (like an hour) will suffocate the bugs and kill them.
An early warning sign for we humans are dizziness and tiredness when we are exposed to high levels of CO2 and we feel better when we leave the area.
When Carbon Monoxide (CO) is taken in by humans, the red blood cells absorb CO2 much more easily than O2 and displaces O2 *permanently*. That red blood cell cannot accept O2 ever again. The only way to get over CO poisoning is a blood transfusion. That is why people become tired when exposed to CO.
There's pretty much no need for CO2 for everyday growers as replacing the air frequently will give your plants all the CO2 they need. I refresh my air twice a minute - yes, twice a minute! And it's cheaper and safer and easier - but quite a bit noisier!
