CDC says COVID19 spreads mainly in the air, through respiratory aerosols and droplets

Through respiratory droplets or small particles, such as those in aerosols, produced when an infected person coughs, sneezes, sings, talks, or breathes.

These particles can be inhaled into the nose, mouth, airways, and lungs and cause infection. This is thought to be the main way the virus spreads.Droplets can also land on surfaces and objects and be transferred by touch. A person may get COVID-19 by touching the surface or object that has the virus on it and then touching their own mouth, nose, or eyes. Spread from touching surfaces is not thought to be the main way the virus spreads.

It is possible that COVID-19 may spread through the droplets and airborne particles that are formed when a person who has COVID-19 coughs, sneezes, sings, talks, or breathes. There is growing evidence that droplets and airborne particles can remain suspended in the air and be breathed in by others, and travel distances beyond 6 feet (for example, during choir practice, in restaurants, or in fitness classes). In general, indoor environments without good ventilation increase this risk.

The idea that COVID spreads via aerosols has been convincing to me from early on into the pandemic even though we hand sanitized like everyone else in the beginning. Protection from aerosolized virus is what drove us to concentrate on ideas for cleaning and disinfecting air rather than surfaces.

UVC is tricky to use for cleaning air as it damages skin and eyes and most devices you see on the market claim to clean surfaces not air.