Heat tolerance testing for mines and hot workplaces
We run heat tolerance testing for mines and hot workplaces in South Africa, from check-in to signed report. Each worker's estimated core temperature, heart rate and sweat loss is recorded on one timeline with the test room's conditions, so every result comes with the evidence behind it.
Weigh-in, 08:52
78.40 kg
Est. core temp
37.4 °C
Heart rate
133 bpm
Room wet bulb
28.0 °C 29.6 °C dry bulb, 89 % humidity
Weigh-out, 09:34
77.80 kg
Sweat loss 0.60 kg, 0.8 % of body mass
Illustrative data. Move across the test, or use the arrow keys, to read every value at that minute.
Show the readings as a table
| Minute | Est. core temp (°C) | Heart rate (bpm) | Room wet bulb (°C) | Room dry bulb (°C) | Room humidity (%) |
|---|---|---|---|---|---|
| 0 | 37.0 | 82 | 28.1 | 29.5 | 90 |
| 1 | 37.0 | 101 | 28.1 | 29.6 | 90 |
| 2 | 37.0 | 108 | 28.1 | 29.6 | 90 |
| 3 | 37.0 | 111 | 28.1 | 29.5 | 89 |
| 4 | 37.1 | 111 | 28.0 | 29.5 | 89 |
| 5 | 37.1 | 110 | 27.9 | 29.4 | 89 |
| 6 | 37.1 | 114 | 27.9 | 29.4 | 89 |
| 7 | 37.2 | 113 | 27.9 | 29.5 | 88 |
| 8 | 37.2 | 113 | 28.0 | 29.6 | 88 |
| 9 | 37.2 | 116 | 28.0 | 29.6 | 89 |
| 10 | 37.2 | 115 | 28.0 | 29.5 | 89 |
| 11 | 37.2 | 117 | 28.0 | 29.5 | 89 |
| 12 | 37.3 | 118 | 28.0 | 29.4 | 89 |
| 13 | 37.3 | 117 | 28.0 | 29.4 | 90 |
| 14 | 37.3 | 120 | 28.1 | 29.5 | 90 |
| 15 | 37.3 | 120 | 28.1 | 29.6 | 89 |
| 16 | 37.3 | 120 | 28.1 | 29.6 | 89 |
| 17 | 37.3 | 123 | 28.0 | 29.5 | 89 |
| 18 | 37.3 | 122 | 27.9 | 29.5 | 89 |
| 19 | 37.4 | 123 | 27.8 | 29.4 | 88 |
| 20 | 37.4 | 126 | 27.8 | 29.4 | 88 |
| 21 | 37.4 | 124 | 27.9 | 29.5 | 88 |
| 22 | 37.4 | 126 | 28.0 | 29.6 | 89 |
| 23 | 37.4 | 128 | 28.1 | 29.6 | 89 |
| 24 | 37.4 | 126 | 28.0 | 29.5 | 89 |
| 25 | 37.4 | 130 | 28.0 | 29.5 | 89 |
| 26 | 37.4 | 129 | 28.0 | 29.4 | 90 |
| 27 | 37.4 | 129 | 28.0 | 29.4 | 90 |
| 28 | 37.4 | 133 | 28.0 | 29.5 | 89 |
| 29 | 37.4 | 131 | 28.1 | 29.6 | 89 |
| 30 | 37.4 | 133 | 28.0 | 29.6 | 89 |
Built around the heat tolerance screening you already run
South African mines have tested workers for heat tolerance since the 1930s.2 Today each mine's thermal stress code of practice follows the Chief Inspector of Mines' guideline (GN R146 of 2016),3 and its heat tolerance screening is a 30-minute step test in a climatic chamber at 28 °C wet bulb, judged on oral temperature at the end.1,3 The mines surveyed in 2025 screen new recruits, then yearly, and again after more than seven days of sick leave or after extended leave.4
That 2025 review for the Mine Health and Safety Council found screening still necessary but the process highly manual: oral, tympanic and whirling thermometers read by hand, little medical or fitness checking before the test, and weak quality control. It recommends heart-rate monitoring during the test, real-time sensors in the climatic chamber and an integrated system to store and transfer screening data.4 That is the service we provide, with your protocol left as it is.
Outside mining, the Physical Agents Regulations (2025) set heat stress limits for every workplace and require medical screening where a risk assessment shows the need.5
Four readings, one record
Everything is captured automatically and stamped with the time, so nothing is copied out by hand.
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Heart rate
From a chest strap paired to each worker, measured every second, so you see how hard the step test is working them from the first minute.
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Weight before and after
Each worker steps on a connected scale before and after the test. Sweat loss is worked out from the difference by the standard method8 and reported as a value, not a pass mark.
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Test room conditions
Temperature and humidity in the test room are logged throughout, with wet bulb calculated from them, so every result shows the conditions it was tested in.
Clipboard and paper, or one digital record
The test itself doesn't change. What changes is how much of it is captured, and how easily you can show it later.
| What is captured | Clipboard and paper | With ScoreVitals |
|---|---|---|
| Body temperature | An oral or tympanic thermometer, read and written down at the start and the end | The same oral readings, plus estimated core temperature about every second in between |
| Heart rate | Not part of the standard test | Measured every second from a chest strap and shown live |
| Sweat loss | Not usually part of the test | Weighed before and after, with sweat loss calculated |
| Test room conditions | Read by hand from a whirling hygrometer at set intervals | Temperature and humidity logged throughout, on the same timeline as each worker |
| The record | A paper form, filed or typed up later | A time-stamped digital record and a PDF report for every worker |
| Earlier tests | In the file, compared by hand | Kept per worker and compared on every report |
| Your other systems | Results keyed in by hand | The outcome sent by API or scheduled file |
| Audits | Paper forms, checked by hand | Every reading time-stamped and every access logged |
Paper-based practice as the 2016 thermal stress guideline and the 2025 Mine Health and Safety Council review describe it.3,4
How a test runs with us
Your protocol stays the same. What changes is that every step of it is recorded.
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Before the test
- Each worker is checked in under their employee number, and their consent is recorded.
- They are weighed on the scale.
- Sensors are fitted at check-in, so the temperature estimate has settled before stepping starts.
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During the test
- Whoever runs the test sees every worker's estimated core temperature and heart rate live, with the room's conditions and the test clock.
- Readings are recorded on the equipment in the room, so a dropped network doesn't lose any of them.
- Your test supervisor stays in charge. The live view shows them the data; it doesn't replace their judgement.
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After the test
- Each worker is weighed again and their sweat loss is calculated.
- A PDF report is ready for every worker, with space for the oral readings and signatures.
- Your occupational health team gets the full record. Your other systems get the outcome.
A report for every worker, and a history that adds up
Every test produces a report your occupational medical practitioner can sign and file. Each one is kept with the worker's earlier tests.
What each report holds
- The worker, the test date and times, and who supervised it
- Estimated core temperature and heart rate through the test, on one chart
- Time in each temperature band, against the lines your code of practice sets
- Weight before and after, and sweat loss
- Test room conditions from start to finish
- Space for the oral readings your result is judged on, and for signatures
- The worker's earlier tests, side by side
- A minute-by-minute log, and a reference number on every page so a printed report can be traced
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Every test, kept per worker
Tests are stored under each worker's employee number, so the next report compares this test with the ones before it.
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Outcomes into your systems
The outcome and its dates can go to your occupational health, HR or ERP system, or your access control, through an API or a scheduled file. We scope the connection with your IT team.
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Exports when you need them
CSV exports per worker or per test session, room conditions included, for your occupational hygienist and your audits.
Health data, handled as health data
Heat test results are health information, which POPIA treats as special personal information.10 This is how we handle them.
- We work as your operator
- We process test data only on your instructions, under a written agreement as POPIA section 21 requires,10 and tell you straight away if we suspect anyone has reached it without authority.
- Consent before the test
- Each worker's consent is recorded at check-in, before any sensor goes on.
- Codes in the test room
- The equipment in the room knows workers by a code. Names are matched only in the protected record.
- Outcomes for managers, clinical detail for clinicians
- Managers and HR see the outcome and its dates. Temperatures, heart rate and weights are visible only to your occupational health team.
- Every access on record
- Each view, export and change is logged against a named user, so you can show who saw what.
- Kept for as long as you need
- Retention follows your records policy and your occupational medical practitioner's instructions, including the 40 years the Mine Health and Safety Act sets for medical surveillance records.9
One team, from set-up to support
You don't buy parts and assemble a system. We bring everything, set it up and stay with you.
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Equipment, supplied and set up
Sensors, heart-rate straps, scales, room sensors and the recording unit, installed in your test room and checked before the first test.
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Set to your code of practice
Temperature lines, test length and report wording follow your site's approved code, not ours.
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Training for your team
Hands-on training for test supervisors and occupational health staff, from fitting sensors to reading reports.
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Support while you test
Ongoing support for your team and the equipment, so testing days aren't held up.
Research and references
The studies, standards and laws behind what this page says. Numbers in the text link here.
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Schutte (2009) — Heat stress management in hot mines. CSIR, Johannesburg. The screening test South African mines have used since 1991: 30 minutes of bench stepping at about 80 W in a chamber at 29.5 °C dry bulb and 28.0 °C wet bulb. CSIR ResearchSpace (PDF)
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Schneider (2016) — Heat acclimation: gold mines and genes. Temperature 3(4):527–538. The history of heat tolerance testing in South African gold mines, from the 1930s to the 30-minute screening test. PMC5198811
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Chief Inspector of Mines (2016) — Guideline for the compilation of a mandatory code of practice for an occupational health programme (occupational hygiene and medical surveillance) on thermal stress. GN R146, Government Gazette 39656, 5 February 2016 (DMR 16/3/2/4-A2). The guideline each mine's thermal stress code of practice follows, including its heat tolerance screening annexure. Guideline (PDF)
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Mhura, Mudzviti, Van Tonder & Mhura (2025) — Is the heat tolerance screening (HTS) test an adequate tool to assess if an employee is heat tolerant and are the methods used to determine heat tolerance valid? Final report, project CoE 190702, Mine Health and Safety Council. How mines screen today, the weaknesses of a manual process, and the recommendation of heart-rate monitoring, chamber sensors and an integrated data system. MHSC eLibrary
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Department of Employment and Labour (2025) — Physical Agents Regulations, 2024. GN R.5952, Government Gazette 52226, 6 March 2025. Heat stress limits and medical screening for workplaces outside mining. Regulations (PDF)
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Verdel et al. (2021) — Reliability and validity of the CORE sensor to assess core body temperature during cycling exercise. Sensors 21(17):5932. A wearable heat-flux estimate against rectal temperature: limits of agreement of about ±0.6 °C. PMC8434645
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Goods et al. (2023) — Concurrent validity of the CORE wearable sensor with BodyCap temperature pill to assess core body temperature during an elite women's field hockey heat training camp. European Journal of Sport Science 23(8):1509–1517. In the heat, the estimate read low, and further below the pill as core temperature rose. PubMed 36939844
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Baker (2017) — Sweating rate and sweat sodium concentration in athletes: a review of methodology and intra/interindividual variability. Sports Medicine 47(Suppl 1):111–128. Sweat loss from body mass before and after exercise, corrected for fluid intake and urine output. PMC5371639
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Mine Health and Safety Act 29 of 1996 — Section 15: record of medical surveillance. Republic of South Africa. Medical surveillance records are confidential and kept for 40 years from the last surveillance date. gov.za
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Protection of Personal Information Act 4 of 2013 — Sections 21 and 26. Republic of South Africa. Health information is special personal information, and an operator processes it under a written agreement with the responsible party. Act (PDF)
Questions mines ask us
Does this replace our heat tolerance screening protocol?
No. Your test runs as your code of practice sets it out, including the oral temperature readings it is judged on. We add a complete, time-stamped record of everything around them.
Who decides whether a worker passes?
Your occupational medical practitioner. Our reports give them the full record of the test; the decision and the certificate of fitness stay with them.
How close is estimated core temperature to the real thing?
It is an estimate from a sensor on the skin, not a reading from inside the body. Independent studies found it can differ from rectal temperature by around 0.6 °C either way, and it tends to read low when core temperature is high. That is why we show it as a trend next to your measured readings, never as the result.
Sources: reference 6 and reference 7.
Is it heat tolerance testing or heat tolerance screening?
Both names are in use. In South African mining the current test is heat tolerance screening (HTS), the 30-minute step test that replaced the older, longer heat tolerance test. We support the protocol in your code of practice, whatever your site calls it.
Do workers need a phone or an app?
No. Workers wear a chest sensor and a heart-rate strap during the test and step on the scale before and after it. The test team handles everything else.
What if the network drops during a test?
Readings are recorded on the equipment in the test room first, so a network drop doesn't lose them. The live view catches up when the connection returns.
Can you test outside mining?
Yes. Smelters, foundries, construction sites and other hot workplaces fall under the Physical Agents Regulations (2025), which call for medical screening where a heat risk assessment shows the need. A heat test can be one way your occupational health practitioner meets it.
Plan heat tolerance testing at your site
Tell us how many workers you screen and where you test them. We'll come back with a plan for equipment, training and reporting.
Talk to us about testing