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A Guide to Managing Risks from Rosin-Based Solder Flux Fumes


This guide is intended for employers and provides detailed insights into the risks associated with rosin (colophony)-based solder flux fumes. The article aims to foster a deeper understanding of the hazards, legal obligations under the Control of Substances Hazardous to Health Regulations 2002 (COSHH), and robust preventive measures to ensure a secure working environment.

Understanding Rosin-Based Solder Flux Fumes

Rosin-based solder flux fumes, a byproduct of soldering processes, pose significant health risks, including occupational asthma and dermatitis. This guide addresses the specific challenges faced by industries, particularly in electronics and assembly, where soldering is a common practice.

Legal Requirements and Comprehensive Risk Assessment

COSHH places a legal responsibility on employers to meticulously identify and assess health risks associated with solder fumes. The process involves thorough hazard identification, risk assessment, the implementation of preventive and control measures, and regular reviews to ensure ongoing effectiveness.

Prioritizing Control Measures for Optimal Risk Mitigation

  1. Elimination and Substitution: Exploring alternatives such as mechanical jointing or conductive adhesives is critical. Additionally, considering rosin-free or rosin-reduced fluxes can contribute to a safer working environment.

  2. Exposure Reduction Measures: When rosin-based flux is necessary, a combination of measures is recommended. This includes implementing good general ventilation, utilizing temperature-controlled soldering irons, maintaining proper worker posture, and deploying local exhaust ventilation (LEV) systems.

  3. Automation and Enclosure: Where feasible, automating and enclosing soldering processes minimizes worker exposure, particularly in production settings. This step is crucial for mitigating long-term health risks.

  4. Personal Protective Equipment (PPE): While PPE is a last resort, its effectiveness is maximized when used in conjunction with other control measures. Employers must ensure that PPE complements the broader risk mitigation strategy.

Ensuring High Standards of Control for Occupational Asthma

COSHH's emphasis on maintaining high control standards is particularly relevant to occupational asthma linked to rosin-based solder flux fumes. Exposure must be reduced to levels as low as reasonably practicable (ALARP) and below the Workplace Exposure Limit (WEL).

Employee Health Checks and Information Dissemination

Apart from providing information on skin checks and offering health surveillance, comprehensive employee training on early symptom recognition related to solder flux fume exposure is essential. Empowering employees with knowledge enhances their ability to contribute to a safer work environment.

Controlling Exposure: Advanced Insights on Working Posture and LEV Systems

Education on adjusting working posture to minimize solder fume inhalation is crucial. For small-scale soldering tasks, proper positioning and adequate ventilation may suffice. However, in production settings, a nuanced approach involving various LEV systems (moveable capturing hoods, ventilated bench-top enclosures, on-tip solder fume extraction, and downdraught benches) ensures effective risk reduction.

Fume Dispersers, Recirculating Ventilation Systems, and Advanced Considerations

  1. Fume Dispersers: While portable and cost-effective, fume dispersers may not offer optimal control. Employers need to carefully assess their limitations and consider alternative options.

  2. Recirculating Ventilation Systems: Properly designed systems reduce the need for extensive ductwork and prevent heat loss. Regular filter replacement and maintenance are critical to avoiding the reintroduction of harmful fumes into the workplace.


By adhering to the guidance provided in this comprehensive article, employers can proactively address the risks associated with rosin-based solder flux fumes. The implementation of appropriate control measures, prioritization of employee health, and continuous monitoring and adaptation of these measures contribute to fostering a work environment where the well-being of employees is paramount.

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