Hidden Dangers in Rubber Moulding: How One Factory Tackled Rubber Fume Exposure

Sysco Environmental Ltd was commissioned to assess occupational exposure to rubber fumes and dust in a manufacturing facility based in Northampton. The site specialises in the production of small rubber and plastic components for the automotive and oil industries, operating across three buildings including rubber moulding, plastic injection, and storage.

Approximately 80 employees work on-site across two 12-hour shifts, with 24 staff operating in rubber moulding and 7 in plastic injection moulding. Key materials used include polychloroprene, EPDM, and natural rubber, processed through injection, automatic, and compression moulding.

Understanding the Health Risks of Rubber and Plastic Fumes

When rubber or plastic is heated during manufacturing, volatile organic compounds (VOCs) and thermal decomposition products are released as fumes. Common health risks include:

• Short-term exposure: Eye and throat irritation, headaches, metal fume fever, and respiratory discomfort.

• Long-term exposure: Development of occupational asthma, chronic bronchitis, potential liver and kidney damage, and in some cases, carcinogenic effects.

Substances such as nitrosamines, PAHs, and various aldehydes formed during curing processes are of particular concern.

In this facility, fume exposure was most significant in the rubber injection and compression moulding areas, with manual trimming and material handling also contributing to exposure.

Monitoring Methodology

The exposure assessment followed HSE guidance L5 and standards outlined in MDHS 14/4 (general dust monitoring) and MDHS 47/3 (rubber fume measurement).

• Sampling Equipment: Personal air samplers with pre-treated filters and 7-hole sampling heads

• Sampling Duration: 11-hour and 7.5-hour shifts, depending on the operational area

• Measured Substances: Rubber dust (inhalable particulates) and rubber fumes (cyclohexane-soluble fraction)

Key Findings

• All measured exposures were below the assigned Workplace Exposure Limits (WELs).

• One operative (in rubber injection moulding) had exposure levels exceeding 50% of the WEL for rubber fumes, indicating a significant exposure, though still within regulatory limits.

• The compression moulding area lacked effective LEV. Existing canopy systems were disconnected and ineffective.

• No significant accumulation of fumes was observed in the plastic moulding area, although no exposure assessment was conducted there.

Recommendations for Control Measures

Local Exhaust Ventilation (LEV)

• Finding: LEV systems were installed in most areas, but compression moulding had no effective LEV in place.

• Recommendation: Install and reconnect dedicated LEV with hoods or flexible arms to capture fumes at source. Fit airflow indicators and conduct 14-monthly performance tests, as per HSG258.

Respiratory Protective Equipment (RPE)

• Finding: Disposable respirators were available but not routinely used; no face-fit testing had been conducted.

• Recommendation: Implement mandatory RPE zones where engineering controls are insufficient. Provide face-fit testing, monthly checks, and sealed storage for masks to maintain filter integrity.

Health Surveillance

• Finding: No formal health surveillance programme was in place.

• Recommendation: Consider introducing a voluntary respiratory health surveillance programme, especially in higher-risk areas. This supports early detection of sensitisation or respiratory decline.

Worker Training

• Finding: Tool-box talks were conducted but lacked formal training structure.

• Recommendation: Provide annual COSHH training covering:

  • Exposure risks and symptoms

  • Use and maintenance of LEV and RPE

  • Reporting defective equipment

  • Employees’ responsibilities under COSHH

Conclusion

The assessment showed that current exposures to rubber dust and fumes were generally within safe limits. However, a significant exposure near the upper threshold was noted, emphasising the importance of proactive control measures.

By implementing the following improvements, the facility can ensure compliance with COSHH and better protect worker health:

• Reinstating and upgrading LEV systems in compression moulding

• Formalising RPE use and storage

• Training workers on exposure control

• Considering routine health surveillance

These steps align with Sysco Environmental Ltd’s approach to minimising risk and keeping exposures As Low As Reasonably Practicable (ALARP).