If one searches for the different levels of CO2 emissions in cars, one can find two very different levels. For instance:

1: Here it is written that:

The law requires that the new cars registered in the EU do not emit more than an average of 130 grams of CO2 per kilometer (g CO2/km) by 2015.

So it can be seen that the mass of CO2 is described as being over 100 grams/km.

2: Here, one can see that the level of CO is around 1 g/km. So way less than 100 g/km, which is a huge difference.

Now, in the second reference, the table shows that those are the values for CO and not CO2, as in the first case. But in the second one, I can't find the CO2 levels and I assumed that the CO is a typo, and it's missing the "2". However, something tells me that it is not a typo and that they read the levels of CO and not CO2. Now, I have two questions.

Is there a typo in the second reference?

If Yes, Q1: Why is the difference so huge?

If No, Q2: Why do they give the values in CO and not in CO$_2$?


1 Answer 1


Q1. The CO is Carbon Monoxide Level, and CO2 is the Carbon Dioxide Level.

The difference is huge because the potent levels for both of them are very different. Generally for clean fresh air there will be between 0-0.5ppm CO, and between 250-350ppm CO2.

Exposing ourselves to around 800ppm of CO will kill us in 2-3 hours, where as we would need to be exposed to over 40,000ppm of CO2 for it to become fatal for an average person dur to oxygen deprivation.

Q2. The reason for some datasets using CO while other use CO2 is usually down to standards within the Governments, Councils, Companies parameters. Certain datasets require CO levels where as others use CO2 levels. Theis could also be due to the questions that are being asked.

  • $\begingroup$ Much lower concentrations of CO2 are lethal, due to respiratory acidosis although the time for acidosis to set in is much longer than for oxygen deprivation. $\endgroup$
    – SF.
    Feb 27, 2017 at 12:24

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