Hi! I have a Masters in electrical engineering, I have more experience soldering than probably most people here.
Flux is not that dangerous as long as you don't get it IN your body. Your computer fan + carbon filter is perfect, because the flux fumes are highly irritating if you breathe them in or get them in your eyes. But flux is mostly just pine rosin mixed with solvents. (To be clear, rubbing alcohol will also damage your nervous system if you ingest or breathe a lot of it. Flux isn't particularly unique).
The risk of lead fumes is incredibly overstated. Lead doesn't even start to vaporize until well into the thousands of degrees, you will never be soldering anywhere near that temperature. You're at higher risk of getting small specks of lead stuck to your hands and then accidentally in your mouth, which is why I always recommend washing your hands immediately after soldering or just touching the equipment.





