I am not convinced a single lamp placed over the dining table would provide sufficient irradiance to inactivate viruses and other pathogens in the large room. Consider having an infected individual sneeze or cough at the table. The expiration jet would spread so rapidly. This lamp is like a tiny flashlight placed above the dining table. Furthermore, far UV gets absorbed by oxygen in the air. The net irradiance of far uv is worse than 254 nm at a fixed distance from two equivalent (in power and form) sources.
The lamp would be effective if you were able to quickly circulate the air in the room past the lamp.
The lamp would be effective if you were able to quickly circulate the air in the room past the lamp.