@whitequark @mmu_man if you are a beginner who will breath the vapors with no ventilation, or maybe just open a window nearby... you are likely much safer breathing in the vapors from lead solder. The temperature is lower, the flux chemicals are less toxic, and the lead is not being vaporized, so it's not an inhalation risk.
Even as a professional I work this way. On production boards the calculus is different. We use lead free for that. It is legally required too.