BL and CRT
 

I noticed that when I have my blacklight turned on (20w, so not the ones you put in cases), my CRT screens radiate a diffused green light (when turned off, when they are on you can only notice it on black parts of a photo).

Is this bad for those screens ? Or not ?

High voltage (CCFL - Blacklight - Neon - ...) devices emit electronic or magnetic radiation.

A ctr screen "fires" small electrical parts to a fosfor layer on the screen itself.

The influence of the electrical devices make the small electrical parts miss their exact position. That's why you have "weird" colors.

I have no idea if it's unhealthy for your screen. But isn't it possible to move the CRT or the BL away from each other ?

Not realy, the BL light up the whole room :D

but the light and the EM are different, EM doesn't radiate that far.

but I think it's more a reaction of the phosphorus layer of the crt to to the UV light. Not sure though.
It might reduce the lifetime of the crt because of the over activity of the phosphorus layer, but with such a low intensity it won't be much.
That's besides the headaches you get from watching a screen with some off colors.