What does the air exchange rate say about effectiveness of air purifiers?
Anyone who has had to deal with air purifiers in recent months has been spoiled for choice. Which air purifier is the right one? What criteria need to be taken into account? Decision-makers had to weigh in different filter technologies, quality criteria and units of measurement. It was, and still is, about nothing less than healthy indoor air - and the health of children, employees, customers and patients. What role may the air exchange rate play in selecting the right air purifier?
New study calls air exchange rate into question
A new study by the German Hermann Rietschel Institute for Energy Technology at the Technical University of Berlin has now clarified the question of what significance the dimension "air exchange rate" actually has. Air exchange rate is initially defined as the volume of supply air in relation to the volume of the room. But is it really a valid criterion for measuring the effectiveness of ventilation measures and air cleaners?
No, say the experts, this value is not meaningful enough. That's because it "makes no statement whatsoever about the distribution of supply air in the room or the removal of pollutants from the breathing zone." The study, sponsored by Germany's Federal Ministry of Health, concludes "that the air exchange rate is not a gauge of risk exposure when the hazard comes from a single pollutant source, because it undercuts differences in local concentrations and thus potential dose."
Pay attention to these criteria for air purification
According to the Berlin researchers, in order to better assess the effectiveness of ventilation measures and air purification, or the actual exposure risk, a different indicator is needed. Such an indicator should be able to describe factors such as the spatial distribution of aerosol particles, the pathogen concentration and exposure time, and thus the inhaled dose. For Carsten Hermann, co-developer of AiroDoctor®, these statements do not come as a surprise:
"We were already aware of similar results from South Korean scientific research. It's good to see that the current study draws equivalent conclusions. The only question is how many air purifiers have been selected in recent months based on criteria that don't matter at all for infection control."
According to Hermann, the effectiveness of air purifiers is shown above all in a powerful, hazard-free filter technology. Therefore, one should definitely pay attention to corresponding ISO certifications and expert opinions.