Corona, like many other viruses, spreads mainly via aerosols. The risk of infection is therefore high when many people are close together and there are not enough fresh air changes per hour.
Filters that remove hazardous substances from the air already exist. They are tried and tested for filtering pollen or dust particles, thus helping allergy sufferers. However, virus filters have higher requirements. Filters that can remove viruses out of the air have to be so-called HEPA (High Efficiency Particulate Air) filters.
Air filters using UV light are very efficient and offer a number of advantages.