If you want to sell your products in any civilised country you will be using lead free solder.
Creating lead vapour that you can breathe in with a soldering iron is impossible. It has a boiling point of 1749°C, and the melting point is only just below what you are soldering at. If you compare that to water, your solder is a block of ice, and when you are soldering you're melting the ice to tap water (or colder) temperature. You have to put the water in a kettle and heat it up to about 50% of its boiling point (50°C) to get it to start steaming. For lead that'd be around 850°C.
The fumes you see rising off the solder are not metal vapours, they are the fumes from the flux. Most common flux is contained in Rosin, a natural plant product, and it is the vaporisation of that which you see while soldering.
If you really must use leaded solder the main possibility of lead poisoning is through physical contact with the solder (getting lead on your hands) and then eating without washing your hands, thus transferring the lead to your food and then to your stomach.
Incidentally, countries that have banned the use of lead in solder have done so not because of safety or health reasons, but purely because of reclamation and recycling reasons.