Reno, I'll disagree with you.
The UV created by the flourescent bulb is used to excite the phosphor inside the bulb. I would expect that little to no UV escapes the tube under normal operation. Plus glass is not transparent to UV. However, quartz is transparent to UV. That is why quartz halogen bulbs have to have a glass filter to block the UV. That is also why metal vapor lamps have a separate glass bulb around the arc bulb, to block UV.
I expecxt the reason why box store fixtures have such crappy diffusers are because it is cheaper.
