Office, cafe, school or university – there’s often little air movement in enclosed spaces. If you spend a long time in one with lots of other people, you run an increased risk of getting infected with the coronavirus.
Virologists suspect airborne transmission as the cause of a spate of recent outbreaks at meat factories in places like Germany, the US and England.
In order to bring the air in such places to low temperatures, it is sucked out of the room, cooled and then blown back in, explains hygiene expert Martin Exner of the University of Bonn in Germany.
He suggests high-performance filters and UV rays may prevent viruses from being spread through such a system in the future.
But what about other indoor areas? If clouds of coronavirus particles hovering in indoor spaces are what we need to worry about, how can we keep the air in our schools, offices and restaurants free of the virus?
– High-performance filters: The filters recommended by Exner, also known as Hepa filters, have been used for many years, for example in operating theatres in hospitals.
They consist of several layers of synthetic fibres placed on top of each other, says hospital hygienist Michael Pietsch from the University of Mainz in Germany. Coronavirus particles can be separated by the filter through various physical effects on the fibers.
– Disinfection sprays: Some companies and event organizers like theatres and cinemas have been disinfecting rooms by spraying them with disinfectant. Various agents are used, some of which are not entirely harmless. For more than 100 years, for example, room disinfection by means of formaldehyde diffusion has been used, explains hospital hygienist Pietsch.
However, the effort involved is very high, and formaldehyde can also cause cancer, which means that a room cannot be entered immediately.
Alternatively, hydrogen peroxide is also used. One advantage of this is that it decays into water and oxygen, says Pietsch. However, even with this method, a longer period of time must be waited for, since hydrogen peroxide can be harmful when inhaled.
– UV-irradiation: Bacteria and viruses can be killed by UV-rays. However, the method is hardly suitable for disinfecting rooms: In order for the rays to be effective at all, the distance between the radiation source and the object should be 10 to 30 centimetres, according to Pietsch. “Air disinfection would only be possible if the air is moved and thus germs are repeatedly led past the radiation source.” In the food industry, however, the process can still be used effectively, for example for disinfecting packaging.
– Air conditioning systems: Air conditioning systems are probably more common than complex disinfection processes. They provide a supply of fresh air from the outside and then cool or heat it. The old air is sucked out and then either released to the outside or brought back into the interior together with fresh air. “In any case, there is also a reduction in the concentration of germs in the indoor air,” said Pietsch.
Building specialists say a high proportion of outside air offers the best protection against infection in offices, hotels, shopping malls and congress centres, and viral transmission can be virtually ruled out if the systems are properly operated and regularly maintained.
– Ventilation: Even without large technical equipment, the risk of infection indoors can be reduced. The quickest way to ensure air movement is to keep your windows wide open. “In most cases, interiors are warmer than the outside air, so there is a draught from the inside to the outside. This can reduce any virus concentration in the interior,” explains Pietsch. It also reduces the risk of infection via aerosols. However, infections cannot be completely ruled out in this way.
– Masks and distance: Even if everyone has heard it countless times before, wearing masks and keeping a distance is still crucial in preventing the spread of coronavirus infections. Even a simple handmade mask will significantly minimize airflow and protect those around you.
