Measure CO₂ to reduce the risk of infection from aerosols

Scientific studies show a correlation between CO₂ levels and aerosol concentrations in the air. Aerosols are mainly produced when we breathe and speak, and can transmit pathogens and viruses such as corona viruses. Testo's measuring technology can help you detect elevated CO₂ levels at an early stage. Optimum adjustment of a ventilation system enables you to ensure good indoor air quality at all times and prevent airborne transmission of pathogens. This can reduce the risk of infection with diseases such as COVID-19. The German government, for example, also recommends controlling the CO₂ levels in the air by using CO₂ measuring instruments to initiate ventilation measures and thus reduce the risk of infection.

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testo 160 IAQ data logger

testo 160 IAQ data logger
  • Ideal for continuous monitoring of indoor air quality (IAQ)
  • Exceptionally user-friendly thanks to its display of indoor air quality according to the traffic light principle
  • Large display for reading values for CO₂, temperature and humidity
  • Simple to install, integrate and operate
  • Perfectly networked: data storage in the Testo Cloud, real-time alarm via e-mail or SMS (optional in conjunction with an Advanced licence)

testo 440 CO₂ kit

testo 440 CO₂ kit
  • Clearly structured measurement menu for long-term measurements and parallel determination of CO₂ concentration, humidity and air temperature indoors
  • Absolute pressure compensation, calculation of wet bulb temperature, dewpoint and absolute humidity
  • Wireless probe, internal data storage and USB port for data export
  • The IAQ measuring instrument can be expanded with a large portfolio of digital probes

testo 400 IAQ and comfort kit

testo 400 IAQ and comfort kit
  • Standard-compliant determination of the comfort level: PMV and PPD as well as draught and turbulence as per EN ISO 7730 and ASHRAE 55
  • Determination of CO₂ concentration, humidity, air temperature and turbulence, including long-term measurements
  • Intuitive measurement programs, measurement with complete documentation, testo DataControl measurement data management and analysis software
  • The IAQ measuring instrument can be expanded with a large portfolio of digital probes

testo 315-3 CO₂ measuring instrument

testo 315-3 CO₂ measuring instrument
  • High-precision electrochemical CO sensor, shock-resistant infrared CO₂ sensor
  • Visual and acoustic alarm when limit values are exceeded – freely adjustable limit values
  • Robust design
  • TÜV-tested according to DIN EN 50543



Download application example

Application example of CO₂ monitoring in the classroom
Testo application example “Detecting elevated CO₂ concentrations in the classroom using the testo 160 IAQ radio data logger”.

More about Facility Management


What are aerosols?

Airborne transmission through aerosols
Aerosols are the smallest droplets or suspended particles that are released into the air when exhaled. They are only a few micrometres or nanometres in size, so they float in the air and sink to the ground very slowly. The air is breathed out when breathing, speaking or singing. Every person permanently emits CO₂ and aerosols. As a result, pathogens and viruses, such as corona viruses, can be transmitted.

Aerosols in rooms

In general, the risk of infection indoors is significantly higher than outdoors because the aerosol particles remain in the air longer. Due to the increasing aerosol concentration, there is a risk of the undetected spread of pathogens. If the aerosol concentration is sufficiently high, the aerosols can be inhaled despite the (safety) distance. This is known as airborne transmission by aerosols. The lower the aerosol concentration, the lower the dose of aerosols that a person inhales and thus the lower the risk of infection. This risk due to airborne transmission can be reduced by displacement or mixing with uncontaminated air. This requires regular ventilation or optimal adjustment of the ventilation system.
Measuring CO2 with the testo 440

Measuring CO₂ to combat aerosols

Measuring CO₂ with the testo 440

The CO₂ level increases when lots of people are in a poorly ventilated room. From the CO₂ concentration, the probable aerosol load can be concluded. The higher the CO₂ level, the higher the risk of inhaling aerosols that another person has breathed out shortly before. The CO₂ concentration is therefore a type of indirect measurement for possible exposure to aerosols. Indoor air, which is only polluted by human use, is usually assessed by the CO₂ quality. CO₂ sensors can help to detect how polluted the air in a room is. A CO₂ concentration of up to 1,000 ppm (parts per million) indoors is acceptable. For comparison: Outside air has a CO₂ value of approx. 400 ppm.

Air humidity to combat virus-laden aerosols

Very low temperatures and low humidity promote long survival times for viruses on surfaces in the air. Even at medium temperatures of 20-30 °C and low humidity, viruses have a long survival time. Within a range of 40% to 60% relative humidity, however, aerosols shrink to the extent that the salt concentration in the aerosol core increases, causing the germs and microorganisms they contain to be killed. Therefore, in addition to measuring CO₂, regular measurement of the relative humidity is also recommended.
Measuring humidity with the testo 400