Most electronics fluxes aren't particularly toxic, but rosin is a sensitiser - repeated exposure will cause an increasingly severe allergic reaction. Working in

Most electronics fluxes aren't particularly toxic, but rosin is a sensitiser - repeated exposure will cause an increasingly severe allergic reaction. Working in a well-ventilated room is probably fine if you only solder occasionally, but anyone who is soldering regularly should be using a good fume extraction system. https://www.hse.gov.uk/pubns/indg249.pdf https://www.hse.gov.uk/pubns/indg249.pdf