I worked in electronics for thirty years, soldering with 63/37 solder, both in wire form and in dip pots, all indoors and never tested positve for lead in the blood. I asked about this from the industrial health people and was told that lead begins to vaporize at 800° F. If you keep the temps below that level there isn't much chance of inhaling vapors. BUT,the big hazard seems to be ingesting particulate lead from hand to mouth. Don't eat, drink, or smoke while working, and wash your hands and face before you eat, drink, or smoke.