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CO2 measurement technology Why CO2 measurement? CO2 concentration is used as an indicator when assessing indoor air quality. If the CO2 concentration in indoor air is too high (limit value: 1000 ppm), the air feels “stuffy and stale”. Bad air quality in rooms (e.g. offices) can lead to tiredness, lack of concentration and illness (Sick Building Syndrome SBS) and is caused, in many cases, by insufficient ventilation.

CO2 concentration The CO2 concentration in demand controlled ventilating (DCV) 40,000 systems is used to regulate the ppm supply of fresh air. Stationary CO2 transmitters are used and should be checked on a regular basis using hand-held measuring instruments. 5,000 ppm

Human’s expired air: 40,000 to 52,000 ppm

Maximum labour safety concentration (lower toxic limit): 5,000 ppm Bad indoor air quality

1,000 ppm

Ideal ventilation

Limit value for rooms (offices etc.): 1,000 ppm City air: 700 ppm

500 ppm

Over ventilated Fresh air: 330 to 400 ppm

0 ppm

Indoor air quality

Percentage of people who are unhappy with indoor air quality at a specific CO2 concentration 40

Percentage of dissatisfied people (%)

35 30 25 20 15 10 5





1000 1200 CO2 concentration (ppm)






CO measurement technology Carbon monoxide (CO) CO is formed from the incomplete combustion of carbon (fuel). It is very dangerous for human beings because it is highly toxic, invisible and without odour. Why CO develops: - Lack of air - Excess air is too high - Flame cools too early

Highly poisonous CO can get into rooms through defect, badly maintained or falsely adjusted heating systems. The CO level in ambient air is measured to protect people from poisoning by colourless and odourless carbon monoxide.

Just 1600 ppm (0.16 %) CO in breath leads to death within 2 hours.

Carbon monoxide measurement Effect of ambient CO on human body CO concentration in air

Inhalation time and consequences

30 ppm

0.003 %

Threshold limit value (maximum workplace concentration during 8 hour day) for Germany

200 ppm

0.02 %

Slight headache within 2 to 3 hours

400 ppm

0.04 %

Headache in forehead area within 1 to 2 hours, spreads to whole head area

800 ppm

0.08 %

Dizziness, nausea and twitching of limbs within 45 minutes, unconsciousness within 2 hours

1600 ppm

0.16 %

Headache, nausea, dizziness within 20 minutes, death within 2 hours

3200 ppm

0.32 %

Headache, nausea, dizziness within 5 to 10 minutes, death within 30 minutes

6400 ppm

0.64 %

Headache and dizziness within 1 to 2 minutes, death within 10 to 15 minutes

12800 ppm

1.28 %

Death within 1 to 3 minutes

Indoor Air Quality  

Bad air quality in rooms (e.g. offices) can lead to tiredness, lack of concentration and illness (Sick Building Syndrome SBS) and is caused,...

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