The lead in the solder does not vaporize or oxydize while soldering. The only fumes are from the flux, which are not particularly harmful. Splashing melted solder on bare skin is the greatest hazard.
well i just checked if its pure lead in the solder then boiling point of lead is abt
1749 deg celcius
i think soldering temp hardly goes beyond 400-500 deg centigrade.
so no apourisation of lead i believe.
Ensuring you are soldering in a well ventilated area is probably the most important point (or look at an extractor as Gadget has suggested). As has been stated previously, the fumes are from the flux, and whilst quite benign they can be an irritant.