In our opinion, some companies are putting out products that are not very effective. Products that rely only on the exposure from direct UVC rays and convection airflow will not sufficiently clean the air in the rooms they are placed.
The viruses and bacteria in the air do not come in direct contact with UVC rays long enough to really sanitize the room. Theoretically, if the room was closed long enough and received no extra infectious material would certainly be cleansed.
That’s not how our world works. We live, play, work, and learn in the real world in real-time. Things are happening, people come and go. People breathe, sneeze, and cough. Buy UVGI filtration that actively cleans the air. While some sanitization happens through direct UVC rays and convection, there is not enough in most cases for it to be considered effective.
We have seen products that have a 10-watt UVC bulb with no fans or vents for convection airflow. These units produce 4 watts of UVC radiation and are effective for about 6 feet. Some of these products sell for over $1200.00 and do very little to clean the air. Ask what UVC dosage their product provides! More than likely the salesperson has no idea. The principle of air changes per hour in still very important. 2 ACH of effective UA-UVC (upper air UVC) is a good deterrent against viral particles.