From the research done here, UVC is an option. If you UVC the drop box,

Greetings, everyone! These are the responses I’ve received, regarding UVC systems. It’s not likely we will pursue them due to the costs, but I’m keeping an open mind. Thanks, as always, for sharing your collective wisdom! _____ We just got our order for UV filters that are going into our HVAC system, I can forward you what we got. I will say it costs a lot, but I was able to get a grant to help offset the costs. _____ then it gets the outside of materials and books need insides done. Demco has a model for books that does 3 books open, books are put in for a set amount of time, then you put in another 3 books. Sounds really cumbersome, and the cost is $5000.00. And UVC is a known carcenogin. I decided that quarantining material is a better option. _____ We are very early in the process of a renovation and as I was meeting with our architect he suggested installing plasma air purifiers in our two heating/cooling units. I had them installed last week as part of our annual heating inspection. They cost $848 each (installed) which included a $50 discount for each because we had them installed at the same time as the inspection. They are small, use the existing 24 volt power in the furnace, and mount on the ductwork. The only drawback is the ventilation fans have to be on all the time to maximize their effectiveness. I hadn’t thought about this but it makes sense so we turn the fans on in the morning when we turn up the thermostats and put them back on normal mode in the evening so they are not running 24/7. Here is the link to the brand they installed: https://www.rgf.com/products/air/reme-halo/ _____ Eau Claire installed UV lights in our duct work many years ago. I hadn't thought of it in years. When all of this COVID stuff happened, I called our furnace people. They said that checking the lights is on their checklist and that they have been maintaining them. I have no idea of how it works, but we had a board member at the time who insisted that we needed to do that. I think it was about 12-14 years ago. _____ I saw this in the paper today. Beyond that I do not have any insight. If you hear from anyone I would love to see your responses. https://www.detroitnews.com/story/business/2020/11/30/rochester-hills-compan... _____ The Hamburg Township Library back in May install two units into our the main library units. We used Lakeside Service out of Brighton Michigan. See attachments of the units we used. The price was $1,075 per unit back in May. You can contact this company for more information or discuss the possibilities for your building: John T Boylan General Manager ACCA certified residential design specialist NCI certified airflow diagnostics NCI certified combustion BPI certified building analyst Mobile 810.533.1731 Office 810.227.2719 ext 213 jboylan@LakesideService.com -- Sharon Crotser-Toy Director *Watervliet District Library* 333 N. Main Street Watervliet, MI 49098 269-463-6382 Connects People, Inspires Ideas, Transforms Lives