Carbon dioxide icon

Carbon dioxide (CO₂)

Carbon dioxide (CO₂) is one of the natural components of air and an important greenhouse gas in the earth's atmosphere. Excessively high carbon dioxide concentrations indoors lead to lower performance and fatigue and even life-threatening respiratory distress.

Can be measured with:

✓ Measurable with air-Q light, air-Q basic and air-Q pro as well as air-Q science

Description of carbon dioxide:

Carbon dioxide is odourless in low concentrations. At high concentrations, the climate gas emits a pungent to sour odour - this is also perceived by humans. CO₂ is heavier than oxygen, for example, and accumulates on the ground and in depressions.

In the history of the Earth, the carbon dioxide content in the Earth's atmosphere has fluctuated greatly. The first measured carbon dioxide values from 500 million years ago indicate a CO₂ content of approx. 8,000 ppm (parts per million). For very different chemical, biological and physical reasons, this level fell continuously to below 2,000 ppm. For at least 800,000 years, the carbon dioxide concentration has always been below 300 ppm. Particularly due to industrialisation and the associated combustion of fossil fuels, the CO₂ content rose again for the first time to today's value of up to 415 ppm.

Limit values for carbon dioxide:

The proportion of carbon dioxide in the air we breathe today is approx. 415 ppm (corresponds to 0.04 % of the air). The exhaled air of a human being has a CO₂ content of approx. 40,000 ppm. Accordingly, concentrations of up to 5,000 ppm can quickly be measured in unventilated bedrooms, fully occupied classrooms or meeting rooms.

And these high carbon dioxide concentrations are harmful to concentration, performance and health in general.

The Federal Environment Agency therefore recommends letting fresh air from outside into the room as soon as a value of 1,000 ppm CO₂ is exceeded. The so-called maximum workplace concentration, also known as the MAK value for short, is given as 9100 mg/m³ (equivalent to just under 5,000 ppm). DIN-1946-2, which is no longer valid today, stipulated a limit value of 1,500 ppm. 

Designationning Carbon dioxide limits
Recommendation Federal Environment Agency 1,000 ppm
DIN-1946-2 Limit value for good air quality 1,500 ppm
MAK-Value for workplaces 5,000 ppm

Consequences of too high CO₂ concentration:

CO₂ concentrations above 1,000 ppm have been shown to cause more mistakes to happen at work. This can happen, for example, due to lack of concentration or headaches when calculating, with regard to spelling or finding spelling mistakes when editing.

If the carbon dioxide content rises to 2,000 ppm, poor concentration and fatigue can be observed. Above 5,000 ppm, a significant decrease in performance and the development of headaches can even be expected.

The problem is that symptoms such as poor concentration or headaches occur long before the indoor air is consciously perceived as bad.

With increasing CO₂ content, the respiratory time volume increases continuously and can even become life-threatening. A carbon dioxide concentration of approx. 80,000 ppm leads to respiratory distress and death after 30 to 60 minutes.

Formation of carbon dioxide

Carbon dioxide is produced during the complete combustion of carbon-containing substances such as plant residues, oil, for example in the form of fuel, as well as in the organism of living beings as a product of cellular respiration. Incomplete combustion, on the other hand, produces carbon monoxide.

Indoors, in addition to people breathing and possibly animals, combustion processes (gas cooker, oil/wood/charcoal/gas cooker, candles, tobacco products, etc.) are the main sources of large amounts of CO₂. These can typically be gas cookers, candles, cigarettes and cigars, or stoves that burn oil, wood, coal or gas. Similarly, CO₂ is released to a lesser extent from carbonated beverages.

Sensor used:

Carbon dioxide is measured by means of an optical sensor. This is based on the principle of infrared absorption. The CO₂ molecule absorbs certain wavelengths of infrared radiation. This is also the reason for the greenhouse effect, for example, because this thermal radiation cannot leave the earth. The sensor measures how high this is. To achieve maximum accuracy, the intensity of the infrared LED is additionally monitored with a second measuring beam. The advantage of this principle over single-beam measuring methods is high accuracy. There are no disadvantages. The sensor we use has no known cross-sensitivities to other gases.

Measure carbon dioxide:

Measure carbon dioxide as well as pollutants in the indoor air of your office or home in real time - with the air analyser air-Q, which can be ordered here.

air-Qs, which use the sensor for

Carbon dioxide (CO₂)


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air-Q Air Quality Meter

Monitor air quality, all air components and environmental influences with the air-Q. For your health and performance.