Summary: Yes it works; it doesn’t affect the penetration rate significantly, but it does reduce the strength of the mask, making it liable to tear or break.
I wondered what the energy output of my bulbs will be in joules/cm (as per above article).
This article has responses that are useful.
Bulbs requires time to warm up and achieve most potential uvc emission. Responder suggests at least 10mins.
The potency of a bulb reduces with age. A bulbs life expectancy is around 1000hours. Suggest a timer and clipboard to record run time.
Article here about hacking a uv sensor and an Arduino to measure UV-C.