Carbon dioxide (CO2) is a greenhouse gas that plays a crucial role in maintaining the planet’s temperature. However, CO2 emissions have increased significantly over the last few centuries, mainly due to the growing use of fossil fuels to produce energy and consumer goods.

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Published on 11 December 2023

What are the characteristics of carbon dioxide (CO2)?

In this article:

Carbon dioxide, a dangerous gas?

Carbon dioxide is an odorless, colorless gas invisible to the naked eye. Also known as carbon dioxide, it is non-toxic to health.
Its molecular formula is CO2, so it’s made up of two oxygen atoms and one carbon atom. It occurs naturally in the atmosphere. Living beings release CO2 through respiration, so it’s essential to life.
CO2 is produced by many human activities, including the combustion of fossil fuels such as oil, natural gas and coal. The average French person emits 11 tonnes of CO2 a year, or around 32 kilograms a day.

Not to be confused with carbon monoxide (CO), a highly toxic, deadly gas that considerably reduces air quality. Equally odorless and invisible, it is produced by the incomplete combustion of carbonaceous materials such as coal, wood, gasoline or propane.


A little history

CO2 was first discovered in 1750 by Joseph Black, a Scottish physicist. To do this, he studied chalk and its transformation into quicklime. During this metamorphosis, he realizes that a mysterious gas is being released. This gas is temporarily referred to as “fixed air”. Many scientific experiments later, this gas was renamed “carbon dioxide”.


Where does carbon dioxide come from?

  • CO2 travels constantly through the environment. It is produced by numerous human and natural activities. Its sources can come from :
  • The combustion of fossil fuels such as oil, natural gas and coal;
  • Breathing in living beings ;
  • The decomposition of organic matter such as dead leaves, plant and animal remains;
  • Agricultural activities such as fertilization or fermentation.

Carbon dioxide can develop in a dwelling or even a building. It comes from :

  • Wood, oil, gas or electric heating appliances;
  • Individual gas boilers ;
  • Household appliances such as refrigerators, freezers and air conditioners;
  • Household equipment such as ovens, stoves and space heaters;
  • Tobacco smoke, starting a vehicle in an enclosed space…

Carbon dioxide is present everywhere, in homes and businesses alike. In normal concentrations, it is not harmful to the human body. However, when these densities are too high, they can affect metabolism.


What are the effects of carbon dioxide on humans?

A little science

Depending on the degree of exposure, carbon dioxide can have more or less serious effects on the human body. CO2 spreads in the same way as oxygen. When we breathe, air containing CO2 enters the lungs and is transported to the pulmonary alveoli. Sent into the bloodstream in the form of bicarbonate, it is carried to the body’s tissues by red blood cells.
When CO2 levels are too high, the body reacts by increasing respiration to eliminate excess CO2. This can lead to faster breathing and a higher heart rate.

The effects of co2

The effects of CO2 vary according to :

  • The amount of carbon dioxide in the air
  • The person’s sensitivity and state of health
  • Duration of exposure to CO2

A low level of CO2 in a dwelling indicates that the air circulating in it is sufficiently rich in oxygen. On the other hand, if CO2 levels in the premises are too high, they have an impact on cognitive ability and performance. Symptoms appear more rapidly with physical exertion, due to the increased inhalation rate.
The level of carbon dioxide in the air is measured in Parts per Million (PPM). CO2 emissions into the atmosphere have risen from 180 ppm to 400 ppm since 1850. In less than two centuries, carbon dioxide emissions have more than doubled.
In a confined space, CO2 concentrations can quickly rise. Humans naturally release CO2 with each exhalation. Confined, unrenewed air can cause headaches, fatigue, dizziness and lightheadedness.
Depending on the CO2 threshold reached, the effects vary:

  • Up to 450 ppm: normal air concentration level;
  • 1000 to 2000 ppm: sensations of numbness ;
  • 2000 to 5000 ppm: headaches, drowsiness, difficulty concentrating, loss of attention, slight nausea and increased heart rate;

The Occupational Exposure Limit (VLEP) established in France by theINRS (Institut National de la Recherche Scientifique) for a working day equivalent to 8 hours, is 5000 ppm. Above 40,000 ppm, CO2 can cause permanent brain damage, coma and even death.
Controlling your exposure to this gas can help prevent poisoning.

How to prevent carbon dioxide?

There are several ways to prevent CO2 in confined spaces. When CO2 levels are too high, here are the steps you can take to improve air quality:

  • Ventilate the premises by opening windows and doors;
  • Use energy-efficient heating and cooling equipment;
  • CO2 sensor;
  • Minimize the consumption of fossil fuels such as coal, oil and natural gas;
  • Follow safety instructions for work in confined spaces;
  • Insulate your home as best you can.

Carbon dioxide is an odorless, colorless, inert gas that is harmless in small doses. However, to prevent CO2-related accidents as effectively as possible, we recommend fitting a carbon dioxide detector. This safety device will emit an audible and visual signal to room occupants in the event of CO2 detection.