Rosin also known as colophony is the sap that comes from pine and spruce trees. Rosin (colophony)-based solder flux fumes is a substance released during the soldering process.

Hazardous substances in the work environment are subject to the provisions of the Control of Substances Hazardous to Health Regulations 2002 as amended (COSHH). These Regulations require that the exposure of employees to substances hazardous to health should be prevented or, where this is not reasonably practicable, adequately controlled.

Rosin-based solder flux fume has been classified as a substance that may cause asthma. Rosin-based solder flux fume is also classed as a hazardous substance under the COSHH Regulations and exposure must be controlled to be at least below the WEL (work placed exposure limit).

The HSE fined a national company in Gloucestershire £100,000 and £30,000 in costs when they failed to have adequate control measure to remove rosin based fumes from a workshop area. The need for control or to replace the rosin based solder with a rosin free solder was identified in 1999 but not put into place till 2003.

First Environment was asked by a client to investigate the concentrations of rosin-based solder flux fumes from the testing of wire components for soldering strength.

The initial investigation found that the concentrations of solder flux fumes in air were above the WEL. The material could not be replaced and the process was necessary for the clients work. First Environment worked with the client to find a solution to their problem. Previous to the initial monitoring no LEV (Local exhaust ventilation system) had been used. With FELs help the client found a suitable LEV system and further monitoring after its installation showed the results to be significantly below the WEL for rosin-based solder flux fumes.

Contact with solder fumes and residues may cause skin problems such as contact dermatitis gloves were recommended when the rosin based liquid was being used. It was also recommended that employees that may be exposed to the rosin based soldering fumes undergo regular health surveillances and that regular monitoring was conducted.