Is CO2 a reliable indicator of indoor air quality?

Indoor air pollution, a serious issue that is not sufficiently addressed

The average person consumes between 10 and 15,000 litres of air every day! This is huge. In comparison, it consumes 2 litres of water and 1.5 kg of food in general. Unfortunately, this air is often more polluted than the outside atmosphere, particularly because of carbon dioxide, but this is far from being the only gas whose emissions are harmful.
A source of energy, poor ventilation, too little ventilation, high humidity, chemicals, scented candles, incense not enough sunshine… sometimes it becomes difficult to breathe clean air in your own home.
Are you afraid to breathe outside because the air is polluted? Start by improving your indoor air quality! Outdoor greenhouse gas emissions are responsible for global warming, rising sea levels, and species extinction… but carbon dioxide-laden air is also to be avoided.
However, despite its possible health effects, it would appear that the carbon dioxide content of air is not a good indicator of air quality.

What does ANSES say about carbon dioxide air pollution?

As we have seen, the air in your house or flat (but also in schools and public buildings) is more polluted indoors than outdoors, even though we spend 80-90% of our time there. The effect of polluted air on health is not the best, as you would expect… and carbon dioxide, of course, has a role to play in this pollution.
However, the French National Agency for Food, Environmental and Occupational Health and Safety (ANSES) points out that human occupation is responsible for most of the CO2 emissions inside a building. The production of energy and especially heat can also cause emissions of harmful gases, such as carbon monoxide or carbon dioxide. Of course, burning wood or oil is known for this.
The agency points out that carbon dioxide is an indicator of the level of containment and the quality of air renewal… but that it is not the same as an indicator of air quality.
However, it recommends that schools and other public places should have sufficient air exchange to avoid exceeding 1,000 PPM. This is a threshold of carbon dioxide in the air which undesirable effects are experienced (e.g. impaired reasoning).

According to the ANSES ESC, carbon dioxide is not a reliable indicator of indoor air quality

The ESC is a specialised expert committee on "Risk Assessment of Airborne Environments" in conjunction with ANSES. In 2013, it was cited in a detailed 294-page report soberly entitled "CO2 concentrations in indoor air and health effects". The report denies that carbon dioxide is a good indicator of indoor air quality.
In fact: "The ESC recommends that no indoor air quality guideline value (IAQG) for CO2 should be developed, either for its effects or for the health effects of confinement. The measurement of CO2 alone cannot be considered as an indicator of indoor air health quality because of the results of this work.”
The reasons for this are explained as follows:

• "The available epidemiological data does not allow us to construct a threshold value for CO2 that protects against the effects of confinement on health, on the perception of comfort or on performance";
• "The probability of exceeding health target values or indoor air quality guidelines (IAQG) for chemical pollutants in indoor air is not zero even for reduced CO2 concentrations.”
  In the absence of sufficient epistemological data, there is therefore no reference framework for setting a threshold for inhalation of carbon dioxide in indoor air. So, for the time being, it is considered that measuring only the carbon dioxide level in the atmosphere inside the house is not sufficient to determine the air quality.
  On the other hand, ANSES has established GAIVs for 8 gases and toxic emissions: formaldehyde, carbon monoxide, benzene, naphthalene, trichloroethylene, tetrachloroethylene, particulate matter, and hydrocyanic acid. However, nitrogen dioxide and acrolein have only been proposed. As you can see, carbon dioxide did not even make it to the proposal stage…
  However, this does not undermine the dangers of carbon dioxide. Greenhouse gas emissions remain a major challenge and their reduction or even eradication must be achieved by the beginning of the 21st century. The point is simple: if emissions of greenhouse gases, especially carbon dioxide, are not drastically reduced, global warming could lead to the collapse of civilisation.

Indoor air quality, like the purity of the atmosphere and the health of the environment, plays a vital role for all living things. Overlooking carbon dioxide has been done before, and the consequences were what we are experiencing today: global warming and all the disasters that we are experiencing now and in the future. Don't neglect CO2 at home (or anywhere else)!