As we wrote in our previous blog: when you exhale, CO2 is released, a gas whose concentration in the air can easily be measured. In addition to the Co2 that is exhaled, aerosols are also released into the air during exhalation. Aerosols are small droplets released from the airways while breathing, talking, shouting or singing. These aerosols are small, about 0.5 m to about 100 m. Because these aerosols are small, they can float in space for a longer period of time.
Co2 build-up in a room
As people perform more activities in a room, they also produce more CO2 and therefore aerosols. For example, compared to light breathing, whispering will on average produce 6x more aerosols, just talking 17x more, shouting 34x more and even singing 250x more. Because you can easily measure CO2 in the air, this is seen as an indicator to trace the status of indoor air quality.
Recent scientific research shows that aerosols are the main route of contamination. With an infected person, aerosols contain virus particles that can infect other people. The chance of infection depends on the amount of virus particles that a susceptible person inhales. This means that the risk of infection via aerosols can be reduced by providing ventilation and air purification.
As mentioned before, we can read from the presence of Co2 in the air how the indoor air quality is doing. The higher the CO2; the more polluting particles in the air. So: the better the indoor air quality, the smaller the risk of contamination! That is why you should strive to have a CO2 concentration in the indoor air of a comparable concentration as in the outdoor air (± 400 ppm). Since pollution of the air in an indoor space remains more present, we state that the CO2 concentration must be lower than 800 ppm to speak of reasonably good indoor air quality.
What if ventilation alone is not sufficient?
For an adult person performing a light activity, a minimum ventilation flow rate (this is the amount of air that must be refreshed/cleaned per hour, per person) of 40 m3/h is necessary. This minimum value will be higher for intensive activities as more CO2 and aerosols are then produced.
In practice, we see that it is not feasible in most buildings to adjust the ventilation systems in such a way that they provide sufficient ventilation flow to reduce aersols and CO2.
Difference between ventilation, airing and air cleaning?
When ventilating, a mechanical system provides a certain ventilation flow rate per hour. The system brings a certain amount of fresh outside air into the room and discharges part of the inside air outside.
When airing, you open the windows and fresh air flows in. However, this is not ideal in all weather conditions, think of freezing cold or during hot summer days. The people in the room will not feel comfortable with this.
With Air Cleaning the air from the room is drawn in by an air cleaner. In the device, the air is cleaned by several filter techniques and blown back into the room. No ductwork needs to be installed and the air keeps the same temperature.
What action should you take?
To estimate your current indoor air situation, you have to take into account the presence of a mechanical system, nominal capacity of the rooms/building, the ventilation flow rate in m3/h per person, the number of people per room, their physical effort, time in space, CO2 concentrations, etc. So there is a lot to consider. To help you, we have developed a decision tree:
Euromate has a suitable solution for every situation. For the cost of 1 cup of coffee per day you already have an air cleaner for an office, classroom, gym, dining room, nursing room, etc. Get good advice!