Indoor CO₂ concentrations (around 450 ppm) are deemed to be healthy for human beings.
At the same time, at homes and offices where we spend most of our lives, CO₂ concentrations are often close to 2,000 ppm. This is because people exhale carbon dioxide (CO₂) when breathing, and it is accumulated in the room with time.
When the CO₂ concentration increases, we say that the air feels stuffy and lacking oxygen (which is erroneous from a physical point of view since it is the CO₂/O₂ ratio that changes, not the O₂ concentration).
Scientists have long been investigating the impact of high CO₂ concentrations on wellbeing, health, and other aspects of human life. Hundreds of researches prove that, in a stuffy room, people:
In addition, an elevated CO₂ concentration indicates that the room is poorly ventilated, leading to quicker transmission of viruses in case an infected person enters the room.
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This review summarizes the outcomes of 137 studies relating to the effects of CO₂ exposure on human health, wellbeing, and cognitive ability.
Air purifiers and conditioners operate in the recirculation mode, i.e., they treat and improve the air that already is in the room. To reduce the indoor CO₂ concentration, it is required that fresh ambient air (with a CO₂ concentration equal or below 500 ppm) is supplied to the room and stuffy air is removed through an exhaust system.
There are three ways to maintain healthy indoor air with a low CO₂ concentration: