The Hazards of Solder Fumes

Weller®, a manufacturer of soldering products (among other items), explains that "at least 20% of the employees working in the soldering area show clinical symptoms of asthma caused by the work environment" in studies that have been done on workers mostly in the United States and England in the electronics industry.

Soldering is the process of combining two metals via a third metal (the "joint") with a lower melting point than the base metals. In this procedure, the two base metals are not distorted and only the filler metal is melted. There are numerous filler metals, or solder, available for soldering applications.

Although effective, these two forms of solder create fumes that pose serious health risks if not managed properly.


The following paragraph was extracted from OSHA's website (www.osha.gov)

"Lead is used in the soldering process in the form of lead/silver filler metals. When heated, lead oxide fumes are formed. Excessive exposure to lead oxide fumes can result in lead poisoning. Symptoms include loss of appetite, indigestion, nausea, vomiting, constipation, headache, abdominal cramps, nervousness, and insomnia. Lead is absorbed through the mucous membranes of the lung, stomach, or intestines and then enters the bloodstream".

The following is extracted directly from the warning label on a roll of 60/40 rosin core solder.

"WARNING: THIS PRODUCT CONTAINS LEAD AND MAY CONTAIN OTHER TOXIC METALS OR CHEMICALS. Ingestion or inhalation of fumes or particles released through processing could cause lead poisoning or cancer. Absorption of lead is known to cause birth defects and other reproductive harm and may result for example in damage to the blood and neurological systems. Use only with adequate ventilation. Use NIOSH approved respiratory protection when necessary. Wash thoroughly before eating, drinking or smoking. Not for use in portable water service systems. THIS PRODUCT ON FILE WITH ROCKY MOUNTAIN POISON CONTROL CENTER".

OSHA currently defines the exposure limit on "lead inorganic fumes and dusts" to be .05 mg/m3 SOURCE: US DOL/OSHA 5/23/2001.


Flux is a chemical cleaning agent that is used in conjunction with solder in order to remove oxidation from the base and filler metals involved in soldering. It improves the overall flow and effectiveness of the solder. Rosin-based flux is made from extracts of pine tree sap and can cause health problems if fumes from soldering are inhaled. According to the WorkSafe Western Australia Commission, “short term problems can include nose, sinus, eye and throat irritation and skin rashes, and long term problems may include asthma and dermatitis.”

Colophony is the base product of flux. As explained by Weller®, "Colophony is the translucent amber-colored rosin obtained when turpentine is distilled from resin of pine trees." It is composed of roughly 90% resin acid and 10% neutral material. When the flux is heated, colophony has been known to generate fumes including aliphaticaldehydes (like formaldehyde) and "hydrochloric acid and other gases containing benzene, toluene, styrene, phenol, chlorophenol and isopropyl alcohol."

The health hazards associated with solder fumes create long-term discomfort and illness for employees and results in increased employee absence, turn-over and a high number of worker claims for damages (Weller® cites that "90% of all claims in the United States related to soldering occupations involving respiratory diseases are litigated."


The Occupational Safety and Health Act of 1970 states that "employers are responsible for providing safe and healthful workplaces for their employees." [6] It is the employee’s right to inform the employer of workplace health hazards like poor ventilation during soldering. (The Whistleblower Protection Program protects employees who raise health and safety issues to their employers).


Because of the high risk of worker/operator exposure during soldering, OSHA suggests Ventilation as a key to controlling lead exposures:

“Ventilation, either local or dilution (general), is probably the most important engineering control available to the safety and health professional to maintain airborne concentrations of lead at acceptable levels. Local exhaust ventilation, which includes both portable ventilation systems and shrouded tools supplied with ventilation, is generally the preferred method. If a local exhaust system is properly designed, it will capture and control lead particles at or near the source of generation and transport these particles to a collection system before they can be dispersed into the work environment.”

Source capture also works effectively for soldering that does not involve lead-based solder. Organizations from The Health and Safety Executive of Great Britain to solder equipment manufacturers, like Weller®, suggest a fume extraction system while soldering.

Sentry Air Systems, Inc. provides this information as a customer service, but cannot be responsible for its accuracy or completeness. It is recommended that competent legal authorities as well as safety and hygiene professionals be consulted.

Download a PDF presentation on the Hazards of Solder Fumes

Loading the player...
  • Portable Floor Sentry
  • Portable Floor Sentry
  • Portable Floor Sentry
  • Portable Floor Sentry
  • Portable Floor Sentry
  • Portable Floor Sentry