On Tuesday, 4 August 2020 23:59:16 UTC+1, wrote:
Easy enough to put some UV C lights in the tube. The airflow will
cool the lights and the lights will disinfect the air.
Disinfection requires dangerous amounts of UVC not compatible with
human occupation.

The UVC would be contained in the air duct.

https://www.puravent.co.uk/blog/in-duct-uv-c/

My point is not that this would be a practical application for the OP; merely refuting the comment that air duct is necessarily a Covid "distribution system".

Owain