"kills germs, especially covid"
There's some misinformation that claims to "kill COVID" (which is a symptom not a virus) so therefore the recommendation is to say "deactivates SARS-COV-2".
Personally I've been trying to reach out to people with scanning electron microscopes, because there's a hypothesis that I'd like to test.
VisualCapitalist have an infographic showing the size of particles, including coronaviruses as 0.1-0.5 microns. I'd assumed a Gaussian bell curve centred around 0.3 micron, but was kindly corrected here on HN that SARS-COV-2 is closer to 0.1 micron.
My hypothesis is that UV-C light at 300 nm = 0.3 micron, or 100 nm = 0.1 micron, will cause the particles to resonate.
In a less formal way, play them the right beat and make the virus dance itself to pieces.
To that end, I bought some UV-C lamps (safely inside plastic boxes) from an aquarium shop. Air filters are all sold out in New Zealand, and suppliers are on holiday. The seller understood, but warned that it can cause sunburn within seconds, and eye damage - so don't look into the blue light! This makes sense because of the size of rod cells in the eye.
Then I got a regular PC fan, and ran it overnight, blowing air through the light. It felt like the air became very dry, and increasingly unpleasant.
Although it didn't smell "fresh", and the window was open for some ventilation, I'm a little worried about ozone production. Not sure how to test that though.
Fabric filters in HVAC will work according to their feature size (like an N95 vs surgical mask), but the difficulty is remembering to change them. So personally I still think UV-C is the solution, I just don't know how to use it safely yet. Certainly it makes sense for disinfecting the mask recycling bins (biohazard infectious substances taken out of the environment = litter picked up) but for ambient air, I'm still learning how to do that safely.