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Carbon monoxide (CO)

Carbon monoxide (CO) is produced, among other things, by the incomplete combustion of substances containing carbon.The colourless, odourless and tasteless gas is a strong respiratory poison that quickly reaches dangerous concentrations in unventilated rooms.

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✓ measurable with air-Q basic and air-Q pro as well as air-Q science


Carbon monoxide (CO) refers to a simple inorganic compound between carbon and oxygen. It is a colourless, odourless and tasteless gas. With oxygen, it burns in a blue, transparent flame to form carbon dioxide. The gas is a dangerous respiratory poison. If it enters the bloodstream, e.g. by smoking tobacco, carbon monoxide binds about 210 times more strongly than oxygen to the haemoglobin in the blood. This can permanently disrupt oxygen transport and cause fatal carbon monoxide poisoning. Even a saturation of 1.28 % carbon monoxide in the room air leads to death within one to two minutes. Because it is lighter than air, it rises to the ceiling.

In industry, pure carbon monoxide is used to produce formic acid and sodium formate. It is also used to convert chlorine into phosgene and methanol into acetic acid. It also acts as a reducing agent for iron ores.

Carbon monoxide limits:

The normal concentration of CO in the air is approx. 0.6 to 6 mg/m³. In unventilated rooms with gas burners, fireplaces or through cigarette smoke, 30 mg/m³ are easily reached.

According to the Federal Environment Agency, the highest 8-hour average value must not exceed around 10 mg/m³. The maximum workplace concentration (MAK value) of carbon monoxide is given as 35 mg/m³. The WHO recommends values above 25 mg/m³ for a maximum of one hour, values up to 85 mg/m³ for a maximum of 15 minutes. The values do not apply to pregnant women or people with pre-existing conditions.

Designationning Carbon monoxide limits
EnvironmentFEDERAL OFFICE 24h-Leitvalue 4 mg/m³ (3.2 ppm)
EnvironmentFEDERAL OFFICE 8h-Leitvalue 10 mg/m³ (8 ppm)
WHO Recommendationling 1h value 25 mg/m³ (20 ppm)
MAK value 35 mg/m³ (28 ppm)
EnvironmentFEDERAL OFFICE LEADvalue 15min 100 mg/m³ (80 ppm)
WHO Recommendationling 15min value 85 mg/m³ (68 ppm)

Consequences of too high CO concentration:

A continuous exposure of eight hours at a CO concentration of less than 60 mg/m³ is hardly dangerous for healthy adults. However, sick and previously exposed persons can experience limitations even at low levels. Hearing loss can be increased by up to 50 % due to carbon monoxide.

Even at a relatively low exposure to carbon monoxide between 80 and 120 mg/m³ over a few hours, the first physical impairments can be observed. These include cold-like symptoms such as a runny nose, headache, shortness of breath and sore eyes.

If the CO concentration rises to values between 170 and 350 mg/m³, fatigue, dizziness and nausea occur after only two to three hours. A value of 460 mg/m³ or more is considered extreme exposure, which is immediately life-threatening. There is a risk of unconsciousness and permanent brain damage. After three hours at the latest, such a concentration can lead to death. At even higher levels, death may occur earlier. After carbon monoxide poisoning, it is not enough just to breathe in fresh air. To compensate for the lack of oxygen in the blood. The compensation of the lack of oxygen in the blood and the regeneration of the body can only take place by supplying a disproportionate amount of oxygen.

One danger in winter (from wood-burning stoves) as well as in summer (from gas heaters) is contracting CO poisoning. Read more about this in the linked blog post.

Formation of CO:

In indoor areas, the carbon monoxide content of the air generally comes in during ventilation - the main source in residential areas is road traffic. Thus, concentrations of up to over 5 mg/m³ can prevail, depending on the proximity of the location to traffic. But also leaky fireplaces and cookers, gas cookers and propane-operated radiant heaters increase the CO concentration. In addition, burning wood, wood pellets or charcoal leads to increased carbon monoxide levels if the ventilation does not work properly and a negative pressure is created in the living space, as when operating an extractor bonnet in the kitchen.

Sensor used:

Carbon monoxide is measured by means of an electrochemical sensor. CO molecules that "dock" on the surface of the sensor cause a small current in the sensor. The advantage of our sensor is the individual sensitivity calibration by the manufacturer and the particularly long service life. Disadvantage of electrochemical CO sensors are slight cross-sensitivities.

The sensor we use has a slight cross-sensitivity to hydrogen (H2). Accordingly, it reacts somewhat to this gas and then shows a deflection even if no CO is present.

Measurement of carbon monoxide:

The air-Q air quality meter and carbon monoxide detector is a particularly powerful and comprehensive air analyser also via a sensor that can measure carbon monoxide in the room air. Many facts about the technology of the air-Q can be found here. You can order the air-Q in the online shop.

How can you protect yourself from carbon monoxide poisoning?

If you experience symptoms of smoke inhalation, immediately provide fresh air by opening windows and call an ambulance. Since an excessive intake of carbon monoxide cannot be reversed, you must protect yourself preventively. With a sensitive air meter, such as the air-Q, you can constantly check the CO concentration and, for example, set an alarm when the limit values are exceeded. This is how you protect yourself from carbon monoxide poisoning day and night.

How does carbon monoxide poisoning occur?

Carbon monoxide can result from the incomplete combustion of carbonaceous components. The causes of carbon monoxide poisoning can be many. The incorrect use of a fireplace, a defective heating system or a blocked chimney can increase the CO concentration in the air.

What happens during carbon monoxide poisoning?

Carbon monoxide is a colorless, odorless and tasteless respiratory poison that is very dangerous when inhaled. CO enters the blood via the lungs and adheres there to the red blood cells, which are responsible for the absorption of oxygen, among other things. Thus, the blood cells can no longer absorb enough oxygen and one suffocates within a very short time.

How do I notice carbon monoxide poisoning?

Carbon monoxide causes various symptoms, such as headaches, dizziness, or feelings of sickness. When too much CO is ingested over a long period of time, carbon monoxide poisoning leads to death by asphyxiation. Especially during sleep, this smoke poisoning often goes unnoticed and leads to death during the night's rest.
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