[rcxdude]

If you're doing it a lot, then it's definitely worth making sure it works properly. If you're doing it occasionally, just make sure the area is well ventilated and you're not outright inhaling the fumes coming off the solder, and it's not likely to make any real difference to the health of your lungs.

[asib]

"Well ventilated" on its own is completely insufficient. If you are soldering without any fan or extraction, you _will_ inhale fumes because you have to look right over your work when you solder, which is exactly where the fumes are.

In general, the danger with soldering fumes is not the average concentration in the room in which you're working over the duration of a session, it's inhaling the very high concentration of fumes right as the soldering happens.

We could debate how much damage this is going to do and whether it's worth worrying about, but there isn't really room to debate that ventilation alone is going to do absolutely nothing.

Well ventilated area + fan is probably okay, but you need the fan right next to your soldering iron or it needs to be a gigantic fan otherwise, again, you are just going to inhale most of those fumes.