I bought a biocidal UV lamp years ago and placed it in an air conditioning
duct.
I had a bee in the bonnet about dust mites.
It turns out, there is a much more effective way to paint unwanted lifeforms
(like anthrax) into a corner - with white paint, so to speak.
Titanium dioxide is an intensely white pigment that shares a desirable
property
with various other metal and semi metal oxides that form the Earth's oldest
rocks:
it is durable. It's a leading pigment for white paint - in some uses it
goes with
'Whiteners' (UV fluorescers). NASA has an application that places UV on TiO2
to generate hydroxyl ions OH- from water, with lethal properties.
Interesting that their motivation was to arrest fruit ripeners in space!