COVID-19 has been keeping the world on tenterhooks for over six months now, and although we learn more and more about the SARS CoV-2 virus, a vaccine is not yet in sight. Meanwhile, the influence of indoor air on transmission is moving into the focus of science. Air quality monitoring devices, such as the Lufft OPUS20 TCO, could make an important contribution to the fight against the pandemic.
They measure the proportion of carbon in the ambient air, specifically, carbon dioxide (CO2). We exhale this after our lungs filter the oxygen from the air and transfer it into the bloodstream. A high CO2 content, therefore, goes hand in hand with a low oxygen content, which can lead to headaches and lack of concentration. We know this as “bad air”.
However, the CO2 concentration is also an indicator of how many particles are in the air that could carry pathogens. The connection that scientists make is as follows: The more CO2 there is in the air, the longer the room has not been ventilated, i.e. the more “stale” the indoor air is. Potentially virus-carrying particles occur less frequently in a well-ventilated room, from which Prof. Martin Krieger from the TU Berlin concludes in a report on German public television ZDF: “I can try to reduce the risk (of infection) by having an air with a low aerosol concentration, i.e. with a high proportion of fresh air”.
Berlin scientists: COVID-19 pathogens hover in the air
Riegel heads the Hermann Rietschel Institute for Energy Technology in Berlin, where he and his team are conducting research into efficient ventilation in enclosed spaces, among other research fields like building energy engineering. In a current project, the Berlin scientists are investigating how droplets and aerosols move and how long they remain in the air before they sink to the ground.
Droplets and aerosols differ primarily in size. Droplets have a diameter of more than five micrometers, i.e. 5/1000 mm. This makes them larger and heavier than aerosols. Droplets fall to the ground faster and enter circulation mainly through the mucous membranes. Aerosols, on the other hand, reside in the air longer, and because of their small size, also reach the deeper airways.
COVID-19 infection via droplets and aerosols
According to current knowledge, half of the COVID-19 virus is transmitted via droplets and aerosols. Germany and other regions are slowly facing individuals return from their home office to the workplace and after the summer holidays, to school. A good ventilation in enclosed spaces can inhibit the spread of the virus.
Indoor climate measuring devices such as the Lufft OPUS20 TCO can provide assistance. “The OPUS20 TCO measures the CO2 content in the air with an NDIR sensor,” says Frank Lehmann, sales engineer at Lufft and expert for indoor climate applications. “This is an optical measuring method. The device uses a light source, the non-dispersive infrared (NDIR) sensor, to detect how many CO2 particles are floating in the air”. The measurement range is 0 to 5000 ppm (parts per million), which is the number of carbon particles per million particles. “Normally, we recommend intensive ventilation from around 1000 ppm upwards,” says Lehmann. This corresponds to 0.1 % of the room air and marks the so-called Pettenkofer-limit, above which the room air deteriorates noticeably, and fatigue symptoms can occur.
OPUS20 gives alarm in case of bad room air
The OPUS20 TCO sounds the alarm and reminds you to ventilate. “However, the alarm can be configured individually and set to any lower value in times of a corona pandemic”, explains Lehmann. Because the device can be operated with both battery and main power, it can be used in any room – alone in a conference room or in combination with other devices as part of a network, for example in schools.
Science is learning more about the virus every day. What is certain is that it will be with us for quite some time. Until then, the following three basic rules remains the most effective means of fighting the pandemic:
- Social distancing, 2. Wearing a protective mask and washing your hands, 3. Monitoring air quality and ventilate regularly.