NavList:

Thanks Geoffrey,

Yes correct. See my latest post where I'm more concerned re infrared for acute "looking at sun with telescope" damage. The UV issue is largely theoretical and long term re things like macular degenereation and cataracts. As Bill Morris said, probably an old chestnut not to worry about.

Sorry if I confused everyone on this! Probably relates to my early house officer  A&E experience of a 23 year old welder blinded (permanently) by a few seconds of un-protected behaviour.(his shade misted up and he temprorarily removed it. ).This clearly infrared, not UV.

Oh well. You tend not to forget such experiences. They occassionally affect your view of potential risks. Better safe than sorry ,since it is no trouble to put a shade filter in , just in case. Bit like the science behind the global warming thing. Not complete, but maybe sensible to take the "precautionary principle" in the abscence of perfect, definitive data. Humans have had to do this for millennia. We very rarley have the complete data set to justify what we do. We are very good at making survival judgements on the basis of limited data. Good people just know what to do. Medicine in UK has  recently been  held back by a naive unrealistic  belief in "evidence based" medicine. I.e. if you do not have the absolute proof,with perfect science (and what  is that? )do nothing.This is rubbish and kills people.( I know from 40 years + experience). An airline pilot sometimes has to do an emergency landing not in the SOP. Show me the double blinded, randomised, prospective  trials to prove that a parachute works! ( I defy you to write an ethical  protocol for such.)

Francis