Rosin based solder flux fume is caused when soldering. This fume is a top cause of occupational asthma.
It affects workers in the electronics and assembly industries.
See COSHH Essentials
[PDF 36kb] for detailed advice on control.
Fume extraction - a soldering booth is best. On-tip extraction blocks up swiftly and needs frequent cleaning. Bench-mounted boxes are useless unless fitted with a HEPA filter.
Maintain the fume extraction system regularly.
You can find more guidance and information on the Further reading pages.