Breathe deeply - reduce the risk of infection: with spexor
How to measure indoor air quality with spexor
How it works
Expert interview with Dr. Richard Fix
Dr. Richard Fix, product manager for environmental sensors at Bosch Sensortec answered the most important questions about indoor air quality and volatile organic compounds measurement and explained, how the sensor built into spexor helps people live smart and healthy lives #LikeABosch.
spexor: Aerosols play a major role in the transmission of Covid-19 . What exactly is this and how are they distributed in enclosed spaces?
Richard Fix: Aerosols are a mixture of solid and liquid suspended particles in a gas. Our exhaled air is such a mixture. If someone is infected, the aerosols also contain viruses and can thus reach other people. Larger droplets and particles in the exhaled air sink to the ground relatively quickly. The smallest suspended particles, however, are only a few nanometers in size and can remain in the air for hours, under the right conditions, so they can be distributed everywhere with normal air currents.
spexor: Does this mean that the risk of infection increases if we spend more time indoors in winter?
Richard Fix: Exactly, and in my opinion, the current infection rate reflects this: in the colder season, we are indoors more often and, usually, the windows are closed. Because of this, there is an increase in exhaled aerosols in the indoor air and, in the case of at least one infected person, also viruses. Due to the higher concentration, there is also an increased risk of infection.
spexor: Does ventilation help and if so, how do you ventilate properly?
Richard Fix: Ventilation is - together with keeping distance, hygiene and breathing mask - an important measure to reduce the risk. Through ventilation, you remove the aerosols and viruses from the room air. Correct ventilation means exchanging the room air as completely as possible. If it is much colder outside, you want to achieve this as quickly as possible in order not to lose unnecessary heat. To do so, open several windows or doors completely (if possible opposite each other, so that there is a draft). This way, a few minutes are enough to completely exchange the air and the walls do not cool down. This should be repeated as soon as the amount of exhaled air in the room has increased.
spexor: How do you find out when you need to ventilate and how can the air-quality sensor in spexor help?
Richard Fix: How often you need to ventilate depends on how large the room is, how many people are in the room and how many windows and doors you can open. There are, for example, apps, where you enter this information, and it calculates how often and how long you need to air the room. An air quality sensor simplifies this enormously. It informs you as soon as the amount of polluted air is too much and you should start ventilating. It also gives feedback as soon as there is enough fresh air in the room and it is better to close the windows again. Too much ventilation does not make sense in winter. Of course, because you freeze. But above all, it is counterproductive. When the room has cooled down and the air in the room is no longer much warmer than the outside air, the air exchange also takes place slowly - you cannot get the bad air out as easily. In addition, cold and dry air ensures that aerosols can remain in the air for a very long time. It is no coincidence that the biggest known super-spreader events in Germany this summer were in refrigerated warehouses!
spexor: In simple terms, what are VOCs?
Richard Fix: “Volatile Organic Compounds“ is the generic term for thousands of volatile organic compounds that can occur in the air. Our exhaled air contains numerous volatile organic compounds, and our air quality sensors are developed and qualified to detect "Breath-VOC" mixture. volatile organic compounds also include vapors and odors, both from us humans and from objects and processes. The German Federal Environment Agency recommends that the sum of all organic compounds in indoor air should remain below a certain concentration.
spexor: What is the difference between measuring volatile organic compounds with spexor and measuring with CO₂ traffic-lights?
Richard Fix: volatile organic compounds sensors can detect almost all organic contaminants in indoor air. That is why they are called air quality sensors. We want to breathe in fresh, clean air, so essentially nitrogen, oxygen and a reasonable amount of moisture. Anything else in the air is usually a contaminant. CO₂ sensors only detect CO₂ and nothing else. The measurement of CO₂ in room air goes back to Prof. Max Pettenkofer, who in 1858 coined the guideline value of 1000 ppm CO₂. From a chemical point of view, however, CO2 itself is a fairly non-reactive gas, that has hardly any effect on our well-being. On the International Space Station (where you can’t open windows ;-)) the CO₂ value is regulated to 5000 ppm. Extensive studies by NASA show that this is sufficient and that it is especially important to filter out all other impurities from the room air. Human exhaled air is reliably detected by volatile organic compounds and CO₂ sensors. A volatile organic compounds sensor may require ventilation a little earlier or more often since it also detects numerous other impurities. We consider this to be sensible.
spexor: How does regular ventilation affect the risk of infection?
Richard Fix: Clearly, the risk of infection is reduced because regular ventilation ensures that no increased virus concentration occurs in the air. More recent studies also assume that an increased virus concentration during infection can also lead to a more severe course of the disease.In other words, if you ventilate properly, you not only reduce the risk of infection but possibly also the consequences of infection if someone becomes infected, nevertheless. The figures of the current infection incidence in comparison to spring speak for this.