When I was 18 I rebuilt the bottom 8" of my Dads Range Rover. It was summer and I had short shorts on (as was the fashion!) and I had got to the rear body crossmember, which when welding it was just the right height to give me badly burnt front and inner thighs!!
I learnt a lesson that day!
I always wear long sleeves. It was too warm and I thought the only danger was sparks. I've welded bare hands before and it never done any harm.
I thought it could only burn eyes and not skin.
Still stinging like mad.
I remember watching someone welding up a opel manta and the body shop had no mask. He closed his eyes everytime he spotted. He didn't come in next day, it looked like he had maximotus. I was only 16 but ill not forget it.
Pulse mig on alloy seems to be nasty for it. Seems to go through shirts that normal mig wont.
A welder will emit both infa red and ultra violet rays.
You ought to use long sleeves. Higher the amps, the worse it gets.