This is extremely wrong: CO2 impairment kicks in around 1000 ppm[1] possibly lower.

You can hit this breathing by yourself in an unventilated 3x3m room (literally measured in my house).

You hit it even easier when driving in a car with the internal circulation turned on to keep nasty fumes out.

	▲	uxhacker 3 hours ago \| parent [-]
		In a car with Recirculation Mode on Levels routinely spike between 1,500 and 4,000 ppm within 20 to 30 minutes. I wonder how many driving accidents can be saved by having a co2 monitor in the car.