It's not brightness but spectral irradiance that matters. You need to compare the spectral irradiance curves for the sun at the earth's surface and that of a welding process that a welding
filter is designed to block. Only public ref I can find is this which shows some significant UV radiation around 250nm greater than 0.5 W*(1/m^2)*(1/nm). The earth's atmosphere cuts out most of the hard UV, especially at sea level and times away from high noon.

So, in fact, welding radiation is more dangerous than the sun since the earth protects us.

Probably talking about this: http://www.justice.gov/atr/public/press_releases/1994/211749.htm

GE and DeBeers got together to fix the price of industrial diamonds back in the early 1990s.

Yup, it's by Eisenfunk. Pong: http://www.youtube.com/watch?v=cNAdtkSjSps
Now that's some Pong.

Snopes is your friend on this one: http://www.snopes.com/humor/letters/hilliker.asp

A similar solution is to use a bluetooth to POTS adapter. Xlink makes a few, for instance
the Xlink BT Bluetooth Gateway. Locate the gateway where you get a good signal and
run a landline down to your basement. Never tried it, but it's got passable reviews at Amazon.