Indoor Air Quality With Testo Instruments

How do I reduce the risk of infection from aerosols by monitoring CO₂?

When we breathe, speak, sneeze or cough, small droplets are released and suspended in the air, they are just a micrometres or nanometres in size, they float in the air and slowly sink to the ground – these are called aerosols. 

Aerosols can transmit pathogens and viruses, including covid-19.  Studies have shown a correlation between CO₂  levels and aerosol concentrations in the air, as we exhale CO₂  is released along with aerosols, the higher the CO₂  levels the higher the number of aerosols.

Ensuring a well maintained and high quality ventilation system will always ensure good indoor air quality and will be beneficial in helping to prevent the spread of airborne pathogens within aerosols.  A CO₂ concentration of up to 1,000 ppm (parts per million) indoors is generally considered acceptable, in comparison outside air has a CO₂ value of approx. 400 ppm.  The levels of indoor or ambient CO₂ can be monitored using various measuring technology, such as the testo 440 IAQ measuring kit, or testo 160 IAQ datalogger which can help you to detect when levels of CO₂ are elevated, even at an early stage. 

The testo 440 IAQ measuring kit offers precise, reliable measurement of  indoor air quality parameters such as ambient CO₂, ambient temperature, and ambient humidity levels within just one measuring instrument.  It offers versatile options with high-quality digital probes, to help you carry out a range of measuring tasks.  After gathering your data, you can then adjust air conditioning and ventilation systems accordingly to help lower the spread of aerosols, and so pathogens and viruses like covid-19.

The testo 160 IAQ datalogger can be used to the same parameters as the testo 440 but will allow longer term monitoring and reporting of measured values. It also offers a flexible ‘cloud’ based solution to storing recorded data and accessing reports documenting any measurements.


A Broader Look At IAQ - 5 Reasons To Monitor Indoor Air Quality (IAQ)

Indoor air quality, also known as IAQ, is measured by a range of parameters including temperature, humidity, airflow, CO, and CO2. When indoor air quality is low this can have a negative impact on the people living/working in that environment. 

There are a range of reasons it is important to monitor and maintain good IAQ, so we have put together our top 5 reasons in this blog:

  1. Improve Comfort – A person's sense of well-being in a room (level of comfort) depends on a series of external influencing factors: temperature, humidity, emissions and even sound can affect workers' well-being.  Any inconsistencies may negatively impact staff health and comfort. Regularly monitoring of these variables which comprise IAQ can reduce the chances of personnel taking sick days, and improve their ability to perform daily tasks.
  2. Improve Cognitive Function – Where there are many people within an environment the CO2 levels can rise quickly.  Higher levels of CO2, combined with warmer temperatures, can lead to people feeling fatigued. There is compelling evidence to suggest increased ventilation leads to us feeling more awake, resulting in improved cognitive function, and feeling overall more energised! 
  3. Prevent The Spread Of Virus Carrying Aerosols – A correlation has been found between higher levels of CO₂ and aerosol concentrations in the air; as we exhale CO₂ is released along with aerosols, the higher the CO₂ levels the higher the number of aerosols. As a result, pathogens and viruses can be easily transmitted.  An IAQ monitor can help you to track and control CO2 levels in an environment, minimising the spread of aerosols.
  4. Keep Up With Changing Regulations – Regulations of what is considered a safe indoor environment continually change as more research is developed. An IAQ monitoring system can help to ensure you are meeting these regulations as they change.
  5. Save Money – With an IAQ monitoring system, such as the testo 160 IAQ, you can continually monitor a range of parameters within an environment – when these levels fluctuate out of your desired parameters you can quickly make changes.


Indoor Air Quality (IQA)



  Carbon dioxide concentration (ppm) Ventilation traffic light Hygienic evaluation Recommendations
Concentrations under 1000 ppm carbon dioxide in indoor air Uncritical < 1000 Green Hygienically uncritical (target value) No further measures
Concentrations 1000 and 2000 ppm Critical 1000 to 2000 Yellow Hygienically uncritical Ventilation measures (increase external air quality/air exchange)

Check and improve ventilation behaviour
Concentration over 2000 ppm Unacceptable > 2000 Red Hygienically unacceptable Check ventilation options of room

Check possible further measures

 Table above taken from the White Paper: CO2 Monitoring & Indoor Air Quality

Learn more about effects of poor IAQ

Testo's White Paper covers:

  1. Formation and effect on human health
  2. CO₂ in indoor air
  3. External air volume flow, ventilation rate and ventilation traffic light
  4. Sick building syndrome
  5. Indoor air quality in schools
  6. Guidelines for CO₂ content in indoor air
  7. CO₂ measurement technology (testo 160 IAQtesto 440 IAQtesto 315-3)