Air purifiers can reduce the risk of coronavirus infection
Exhaled air and micro-droplets of saliva can contain viruses that remain in the air for several hours. Because of them, people can catch the disease while in a room with infected people. Therefore, air purifiers play a rather important role in the fight against the spread of coronavirus: they remove viruses from the air, thereby significantly reducing the risk of infection. These devices let air in the room through small filters, and viruses and bacteria are no longer released back – at least in some cases …
How well air purifiers can get rid of viruses and bacteria depends on several factors. To find out, in 2020, scientists from Germany (Bundeswehr University) conducted a whole study.
In a test in an 80-square-meter room, the air purifier was able to halve viral load in six minutes. It was a purifier that itself filters out aerosol with particles with a particle diameter of 0.1 to 0.3 microns by 99.995%.
Scientists used a highly efficient air purifier with HEPA filter H14 in the experiment. Such filters are available, for example, in the industrial model TAC 750 E. It allows very few viruses to pass through.
“The big advantage of indoor air purifiers is that they provide low viral load and you don’t have to constantly open windows to ventilate. Air purifiers will be especially useful in offices and schools, as well as in waiting rooms, canteens, lounges and shops. Accordingly, in places where many people get together and talk, and where it is difficult to frequently and thoroughly ventilate the room, ”the authors of the study explain.
The research results also show that the effectiveness of a filter is highly dependent on the volume of air it needs to purify. Large rooms require particularly powerful devices that can filter a large volume of air in an hour.
The location of the air purifier also matters, with experts suggesting a performance reduction of about 20 percent depending on location. For example, lamps and other heating elements can interfere with airflow, so it is not recommended to install the cleaner near them.
By the way, the filters do not need to be constantly replaced: when comparing the results of the new filters and the used ones, scientists could not find a significant difference. Therefore, experts suggest that the filter can be used for several years – of course, cleaning it, but not replacing it. Some modern devices are equipped with a rather useful filter heating function: if you use heating up to 100 ° C for half an hour every day, it will help to “kill” viruses that have got into the cleaner.
Cleaner or Sterilizer?
Air purification is most often understood as the fight against natural pollutants: dust, odors … Disinfection, until recently, was used mainly in medical institutions. But after the outbreak of the coronavirus pandemic, “medical” technologies began to be actively used in household devices. Now, in addition to mechanical filters, air is passed through ozonizers, treated with ultraviolet light, photocatalysis is used … One of the progressive technologies in the fight against viruses is air disinfection by exposure to low-temperature plasma.
Do not be intimidated by the name: low-temperature plasma is essentially an ionized gas at room temperature (about 30-40 ° C). Under its influence, the cell membrane of viruses and bacteria becomes vulnerable, plasma particles react with DNA or RNA and destroy it. Thus, bacteria and viruses are destroyed not only in the air, but also on surfaces – in addition, the technology allows you to disinfect water, food, decompose allergens … The technology has been used since the 90s in the sterilization of surgical equipment, as it is the most effective in this direction.
But there are only a few household devices operating on the basis of cold plasma technology: for example, INTECH Technologies introduced a compact Plazmabox to the market, which is capable of eliminating up to 99.9% of viruses and bacteria on an area of 10 m2 and more advanced Plazmatech, designed for an area of up to 40 m2 and one of the largest cleaning radii among sterilizers and air purifiers.
What is more effective in the fight against coronavirus: an air purifier or ventilation?
Isn’t ventilation enough to “drive” viruses out into the street? In principle, ventilation can also reduce indoor viral load when it comes to through ventilation – when open windows are opposite each other. But ventilation cannot seriously reduce the viral load, because sometimes there are no windows at all in the premises (for example, in the corridor) or the windows are not located opposite each other. In addition, for example, in large rooms, the windows will have to be kept open for a very long time.
Many buildings have built-in ventilation systems. However, according to experts, unlike an air purifier, it can create a risk that viruses will not filter, but rather spread through ventilation shafts. Therefore, air purifiers are superior to ventilation systems in terms of efficiency. By the way, the purifier is worth purchasing for other reasons: they are good at removing dust mites, unpleasant odors and pollen from the air and thus provide a better indoor climate.
However, air purifiers are not a substitute for face masks. Because there is still a risk of contracting coronavirus if your interlocutor is sick, and when talking to him you do not keep your distance.
What filters trap viruses
H14 filters fight viruses best – they are found mainly in high-performance air purifiers used in factories. But how good are lower HEPA filters?
Mostly HEPA 13 filters are found in cheaper devices for home use. Even weaker filters are HEPA H7 (they filter out 99 percent of viruses, not 99.995 percent). H7 purifiers take two and a half times longer than H14 filters to remove half of the aerosols from the air. “Filtration of an aerosol even tenfold with an H7 filter is inferior to simple filtration with an H14 filter,” the scientists write in their study.
We advise you to choose a model with a high filter class, although the lack of efficiency of a weaker filter can be partially compensated for by ventilation.