Lead can't really vaporize at any temperature used in soldering. There are other fumes (mostly from flux) to be worried about, and you have to make sure that so

Lead can't really vaporize at any temperature used in soldering. There are other fumes (mostly from flux) to be worried about, and you have to make sure that solder leftovers are well disposed of (especially when desoldering). But lead free is definitely usable now, though I only use it for solder paste.