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The hazard of nickel mine dust depends on what workers breathe in and for how long. Dust from the pit, haul roads, stockpiles, and crushers can carry nickel and, where the rock contains it, crystalline silica. At a smelter, hot processes add metal fume and dust. Indonesia's Minister of Manpower Regulation No. 5 of 2018 (Permenaker 5/2018) sets a threshold limit value (NAB) of 1.5 mg/m³ for elemental nickel (inhalable fraction) and 0.025 mg/m³ for crystalline silica (respirable fraction). Diseases caused by nickel, pneumoconiosis including silicosis, and cancer from nickel compounds all appear on Indonesia's list of occupational diseases.
This article is written for HSE teams and site managers. It covers where exposure happens, how to read the limits, how to measure in line with the regulation, and which controls work at a remote site.
Where are workers exposed to mine dust?
Dust sources and dust types differ between an open-pit laterite mine and a smelter, so map exposure area by area before choosing controls.
| Area | Dust source | Workers usually exposed |
|---|---|---|
| Pit | digging, loading ore into haul trucks | excavator operators, supervisors, survey crews |
| Haul road | tyres on dry road surfaces, graders | haul truck operators, light vehicle drivers, flaggers |
| Stockpile | dumping and reclaiming ore, wind over open piles | loader operators, sampling crews |
| Crushing and screening | crushing, material drop points, conveyors | crusher operators, cleaning and maintenance crews |
| Smelter | drying, furnaces, tapping, calcine and slag handling | furnace operators, tapping crews, dust filter maintenance teams |
At the mine, most dust comes from breaking and moving material. At the smelter, some particles form during thermal processing, so their chemical form may differ from the ore they came from. This matters because the regulation sets a separate limit for each form of a substance.
What are the limits for nickel and silica dust?
Chemical limits are listed in the appendix to Permenaker 5/2018. These two rows matter most for nickel mines and smelters:
| Substance | Limit (NAB) and fraction | Carcinogen notation and remarks in the appendix |
|---|---|---|
| Elemental nickel | 1.5 mg/m³, inhalable fraction (I) | A5, not suspected as a human carcinogen. Remarks: dermatitis, pneumoconiosis |
| Crystalline silica, alpha-quartz and cristobalite | 0.025 mg/m³, respirable fraction (R) | A2, suspected human carcinogen. Remarks: lung fibrosis, lung cancer |
The inhalable fraction covers particles that can be breathed in through the nose and mouth. The respirable fraction is the finer part that can reach deep into the lungs. Each fraction needs its own sampler, so a sampling plan has to state which fraction it is measuring.
Soluble and insoluble inorganic nickel compounds, and nickel subsulfide, have their own rows in the appendix, with limits lower than elemental nickel and the A1 notation, confirmed human carcinogen. IARC Monographs Volume 100C also classifies nickel compounds as carcinogenic to humans (Group 1) and links them to cancers of the lung, nasal cavity, and paranasal sinuses. IARC places crystalline silica in the form of quartz or cristobalite in the same group, naming lung cancer.
How should dust exposure be measured under the regulation?
Article 20 of Permenaker 5/2018 requires chemical factors to be measured and controlled at workplaces with a potential chemical hazard. Its key points:
- Two targets. Measurement covers both the exposure itself and the workers who are exposed (paragraph 2).
- At least 6 hours. Measurements that will be compared with the NAB must last at least 6 hours (paragraph 3).
- Testing on workers. Measurement on workers is done through a special health examination of body specimens, compared with the Biological Exposure Index (paragraph 6).
Article 1 point 7 defines the NAB as a time-weighted average that workers can tolerate for no more than 8 hours a day or 40 hours a week. On sites running 12-hour shifts with long rosters, for example 10 weeks on and 2 weeks off, daily and weekly exposure hours go beyond that basis. The appendix gives no separate limit for longer shifts. Results from 12-hour shifts should therefore be assessed by a competent industrial hygienist, not simply compared with the number in the table.
For mining and for mineral processing and refining, Energy and Mineral Resources Ministerial Decree No. 1827 K/30/MEM/2018 includes dust management in work environment management, with measurement and assessment by competent mining technical personnel (Appendix III, letter A, point 3). For SMK3 audits, Government Regulation No. 50 of 2012 expects work environment monitoring to be done regularly, documented, and used to assess and control risk (criterion 7.2.1). That criterion is covered in our article on SMK3 under PP 50/2012.
Controlling mine dust: from the source to PPE
When exposure results exceed the NAB and results in workers exceed the Biological Exposure Index, control is mandatory (Article 21 paragraph 1). Paragraph 2 lists the options: removing the source, substituting the material, modifying the process, isolating or limiting exposure, ventilation, limiting working time, rotation, safety data sheets and labels, and personal protective equipment. On site, that translates into measures such as:
- Haul roads. Appendix V of Decree 1827 lists routine road watering, planting vegetation, and vehicle speed limits to reduce dust from hauling. The rule is framed around ambient air, but the same steps lower worker exposure. Heavy dust also cuts operator visibility, so dust control doubles as collision prevention.
- Equipment cabs. Closed cabs with maintained air filters, and doors kept shut during operation.
- Crushers and conveyors. Water sprays at material drop points, conveyor covers, and wet cleaning or vacuuming instead of dry sweeping.
- Smelters. Enclosing sources, local exhaust ventilation at tapping points and calcine handling, and safe procedures for opening and servicing dust filters.
A complete respirator programme
Respirators are the last line of defence and only protect when the programme behind them works. The US OSHA standard 29 CFR 1910.134 is a useful reference. It calls for a written programme covering respirator selection, medical evaluation, fit testing, use, maintenance, and training. Check the following:
- Respirators are chosen for the substance, fraction, and level measured in each area.
- Fit testing is done before first use, whenever the mask size or model changes, and at least once a year.
- Workers with facial hair in the seal area do not wear tight-fitting masks.
- Filters are changed on schedule and when their condition requires it, and masks are stored clean outside dusty areas.
- Filter and mask stock is calculated from use per roster, with a buffer for delayed deliveries to remote sites caused by weather or boat and flight schedules.
- Comfort in hot weather is taken into account. Hot, damp masks tend to come off. Pick models workers can keep on for the whole task and provide a clean rest area where they can remove them. Heat load around furnaces is covered in our article on heat stress at smelters.
What do medical surveillance and the site clinic contribute?
Appendix III of Decree 1827 requires pre-employment examinations, periodic examinations at least once a year, special examinations matched to the exposure risks of the job, and a final examination before a worker leaves. Results for high-risk workers are followed up by informing the worker, adjusting their placement, and providing monitoring, treatment, and rehabilitation. Occupational health records are kept, held confidential, and analysed. Common lung checks such as chest X-ray and spirometry are explained in our article on periodic medical check-ups for mine workers.
Presidential Regulation No. 7 of 2019 contains three items directly relevant to nickel mine dust:
- diseases caused by nickel or its compounds (Appendix I, letter a, point 24);
- pneumoconiosis caused by scar-forming mineral dust, including silicosis, and silicotuberculosis (Appendix II, letter a, points 1 and 2);
- cancer caused by nickel compounds (Appendix III, point 13).
An occupational disease is diagnosed by a doctor or a specialist competent in occupational health (Article 3), then recorded and reported, including by the employer (Article 5). A worker remains entitled to Work Accident Insurance (JKK) benefits if the disease appears within 3 years after employment ends (Article 2). In mining, Decree 1827 requires the Head of Mining Engineering (KTT) or the responsible technical manager (PTL) to report occupational diseases promptly to the Chief Mining Inspector.
The site clinic connects exposure data with health data: who worked in which area, the measurements for that area, and each worker's examination results year by year. Good records help a doctor judge the link to work when symptoms appear, including after a worker has moved on or finished a contract.
Exposure mapping, measurement, respirator programmes, and medical surveillance can run together through our occupational health service, with records kept at the site clinic.
