Soldering Fumes
Many people worry about soldering fumes when using Lead containing solder but this is mostly a misdirected concern.
Is there lead vapor in the fumes?
Not likely. Even though the alloy lowers the melting temperature of the lead this does not change the vapor temperatures of the individual metals. There should be no vapor created at the temperature the soldering iron is being used at. The bigger issues come from the flux fumes, not the lead.
Are Flux Fumes bad?
Yes and no. Stained glass mostly uses Zinc Chloride based fluxes that can cause irritation from exposure. Many people compare the flux we use to what people say about electronics flux but these are not comparable as electronics soldering often uses rosin based flux which creates a whole host of other issues. Hobby glass workers should have no worries about flux fumes, simply circulating some fresh air is sufficient.