A research study by South African-based North-West University (the NWU), in collaboration with Copperbelt University in Zambia, has highlighted the hidden dangers of respirable crystalline silica (RCS) in dust generated during underground copper mining, underscoring the need for stronger occupational health and safety measures to protect mine workers.
The research, involving Prof. Stefan Linde of the NWU’s Occupational Hygiene and Health Research Initiative in the Faculty of Health Sciences, highlights the importance of monitoring hazardous dust levels and strengthening workplace controls to protect miners against potentially fatal respiratory diseases.
The study, titled “Occupational exposure to respirable crystalline silica at an underground copper mine in Zambia”, was published in the Annals of Work Exposures and Health in 2025. Led by Lubinda Nabiwa of Copperbelt University, it involved researchers from the NWU, the University of the Witwatersrand and the University of South Africa.
Respirable crystalline silica consists of microscopic particles that can penetrate deep into the lungs when inhaled. Exposure can cause silicosis, an incurable lung disease, and is associated with other respiratory illnesses, including pulmonary tuberculosis.
Mining activities such as drilling, blasting, crushing, loading and transporting ore can release silica-containing dust into the workplace. Because these particles are often invisible to the naked eye, monitoring general dust levels alone may not reveal the full extent of workers’ exposure.
Investigation and findings
To investigate the problem, researchers conducted personal exposure monitoring across 18 activity areas at an underground copper mine over 12 weeks in 2023. Of the 114 samples collected, 111 were included in the final analysis.
The findings revealed a significant difference between general respirable dust measurements and exposure to its more hazardous silica component.
Only one sample exceeded the South African occupational exposure limit for general respirable dust used in the study, while 13 exceeded the applicable limit for respirable crystalline silica.
Statistical assessments further classified 11 of the 18 activity areas as having inadequate silica-exposure control.
The researchers used South African occupational exposure limits as comparative benchmarks because Zambia had no legislated occupational exposure limits for respirable dust and crystalline silica at the time. The findings therefore do not establish violations of Zambian legislation.
The study also found that the proportion of silica samples exceeding 0.05 mg/m³ had declined from 67% in a 2008 investigation to 32.4% in the latest research. However, the mine was operating below full capacity during sampling, potentially influencing exposure levels.
Other limitations included restricted access, budget constraints and relatively small sample numbers in some work areas. The research assessed occupational exposure rather than diagnosing respiratory diseases among individual miners.
Building research capacity through collaboration
Beyond identifying workplace hazards, the partnership between the NWU and Copperbelt University aims to strengthen Zambia’s capacity to conduct occupational hygiene research and address mining-related health risks.
Established in 2021, the collaboration has involved academic exchanges between Kitwe and Potchefstroom, training workshops and postgraduate research support. Prof. Linde visited Copperbelt University in 2022 and 2025 to provide specialised training.
The initiative has also reached academics developing occupational hygiene courses, professionals from two copper mining companies and inspectors from Zambia’s Ministry of Labour and Social Security.
Achievements reported in the partnership’s 2025 showcase include three doctoral candidates at different stages of research, seven published papers and five conference presentations.
Another key objective is establishing a dust laboratory at Copperbelt University to strengthen local capacity to measure and analyse workplace dust and silica exposure.
Developing this expertise locally will help researchers, occupational health professionals and mining authorities identify hazards, assess existing safety measures and make evidence-based decisions.
Turning research into better protection
The study recommends routine silica exposure monitoring in Zambian mines, improved ventilation, effective dust suppression and stronger respiratory protection programmes.
Continuous training is also important to ensure workers understand silica-related health risks and consistently follow occupational safety procedures.
Researchers further recommend that Zambia consider adopting the South African occupational exposure limit for respirable crystalline silica and the BOHS-NVvA 2022 standard for assessing compliance.
For the NWU and its Zambian partners, the collaboration extends beyond academic publications. It seeks to translate scientific findings into practical workplace improvements while developing sustainable research expertise.
By combining research, skills development and improved occupational hygiene practices, the partnership is helping lay the foundation for safer underground mining workplaces in Zambia and potentially other mining communities across the region.
