Heat tolerance screening (HTS) for mines and hot workplaces

Every screening, fully on record.

Today's 30-minute heat tolerance screening rests on two oral temperature readings, one before the test and one at the end, with nothing measured on the worker in between.1 We record every screening live: each worker's estimated core temperature, heart rate and sweat loss, on one time-stamped timeline with the test room's conditions. Your HTS protocol stays as it is.

When the code applies. A mine's thermal stress code of practice applies once its risk assessment finds wet bulb above 25.0 °C. From 27.5 °C wet bulb, the guideline calls it a hot environment.1

Talk to us about a pilot See what we record
Worker W-0412, 30-minute step test End of test

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. Estimated core temperature is a trend beside the oral readings, not the result (about ±0.6 °C).14,15

Show the readings as a table
Readings for each minute of worker W-0412's test
MinuteEst. core temp (°C)Heart rate (bpm)Room wet bulb (°C)Room dry bulb (°C)Room humidity (%)
037.08228.129.590
137.010128.129.690
237.010828.129.690
337.011128.129.589
437.111128.029.589
537.111027.929.489
637.111427.929.489
737.211327.929.588
837.211328.029.688
937.211628.029.689
1037.211528.029.589
1137.211728.029.589
1237.311828.029.489
1337.311728.029.490
1437.312028.129.590
1537.312028.129.689
1637.312028.129.689
1737.312328.029.589
1837.312227.929.589
1937.412327.829.488
2037.412627.829.488
2137.412427.929.588
2237.412628.029.689
2337.412828.129.689
2437.412628.029.589
2537.413028.029.589
2637.412928.029.490
2737.412928.029.490
2837.413328.029.589
2937.413128.129.689
3037.413328.029.689

A 30-minute test, judged on two readings

In South African mining, heat tolerance screening is 30 minutes of bench stepping at about 80 W in a climatic chamber at 28.0 °C wet bulb.1,8 Each mine's thermal stress code of practice follows the Chief Inspector of Mines' guideline (GN R146 of 2016).1

  1. Minute 0

    Resting oral temperature, read and written down.

  2. Every 5 minutes

    Room conditions recorded, often read by hand from a whirling hygrometer. Nothing is measured on the worker.1,13

  3. Minute 30

    Oral temperature again. This reading decides the result.1

What the 2025 review of HTS found

  • Read and written by hand

    Oral, tympanic and whirling thermometers are read by hand, and the readings go onto paper to be filed or typed up later.13

  • Thin checks before the test

    Little medical or fitness screening happens before workers step into the chamber.13

  • Fails that vanish on retest

    Most first-attempt temperature fails don't repeat. The authors read that as a problem with the procedure, not true heat intolerance.13

South African mines have tested workers for heat tolerance since the 1930s, and once acclimatised every new worker in climatic rooms before the 30-minute screen replaced that.9 Acclimatisation works: it improves sweating and lowers body temperature and cardiovascular strain in the heat.30 Today's screen is judged on oral temperature because, in the pilot work behind it, workers resisted more accurate indicators such as rectal temperature and heart rate.10

Mine occupational health centres evaluate at least 50 to 100 prospective and in-service employees a day.11 The mines surveyed in 2025 screen new recruits, then yearly, and again after more than seven days of sick leave or after extended leave,13 and the CSIR provides heat tolerance screening training, assessment and auditing to the industry.12

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.2 The World Health Organization and World Meteorological Organization describe workplace heat stress as a growing challenge worldwide.7

Four readings, one record

Captured live and automatically, with every value stamped with the time, so nothing is copied out by hand.

  • Estimated core temperature

    From a sensor worn on the chest, read about every second for the whole test. Core temperature rises during sustained work in the heat,29 and this shows how it moves for each worker. It is an estimate,14,15,20 so it sits next to the oral readings your result is judged on.

  • Heart rate

    From a chest strap paired to each worker, read every second and shown live, so you see how hard the step test is working them from the first minute. A chest strap tracks an ECG more closely than a wrist-worn monitor,27,28 and heart rate and core temperature are the two inputs of the Physiological Strain Index, a published 0 to 10 measure of heat strain.24,25

  • Test room conditions

    Temperature and humidity in the test room are logged throughout, with wet bulb calculated from them,33 so every result shows the conditions it was tested in. Those conditions matter: in the older four-hour test, pass rates fell from 85 % to 35 % as wet bulb rose from 29 to 31.7 °C.8

  • Weight and sweat loss

    Each worker steps on a connected scale before and after the test. Sweat loss is worked out from the difference by the standard method31,32 and reported as a value, not a pass mark. For context, NIOSH puts the point where heat tolerance starts to deteriorate at a fluid loss of 1.5 to 2 % of body weight.5

Paper form, 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.

A paper-based heat tolerance screening compared with one run with ScoreVitals
What is captured Clipboard and paper With ScoreVitals
Body temperature Oral or tympanic thermometer, start and end Live core estimate about every second, plus your oral readings
Heart rate Not part of the test Live, every second, from a chest strap
Sweat loss Not part of the test Weighed before and after, calculated
Room conditions Whirling hygrometer, read by hand Logged throughout, on each worker's timeline
The record Paper form, typed up later Time-stamped record and a PDF per worker
Earlier tests Filed, compared by hand Kept per worker, compared on every report
Your systems Results keyed in by hand Outcome sent by API or scheduled file
Audits Paper forms, checked by hand Every reading and every access logged

Paper-based practice as the 2016 thermal stress guideline and the 2025 Mine Health and Safety Council review describe it.1,13

Built around what the 2025 review of HTS recommends

The Mine Health and Safety Council review recommends heart-rate monitoring during the test, real-time sensors in the climatic chamber and one integrated system for screening data. It expects the industry to need four weeks to a year for the sensors, and six months to several years for the data system.13 We bring all three, installed and supported.

  1. Defensible results

    Every reading time-stamped and every access logged, so a queried result, or the yearly independent audit of records and instruments the guideline asks for,1 comes with its evidence.

  2. The whole test, not two points

    Your occupational medical practitioner (OMP) sees how each worker responded across all 30 minutes, beside the oral readings.

  3. A history that adds up

    Every test kept under the employee number and compared with earlier tests on each report.

  4. Your protocol, untouched

    Same step test, same oral readings, same OMP decision. We add the record around it.

How a test runs with us

Your protocol stays the same. What changes is that every step of it is recorded.

  1. 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.

  2. 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.

  3. 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.

What we install in your HTS room

Supplied, installed and supported by us. Everything runs on your local network, and readings are recorded in the room first, so a network drop never loses them.

Per worker, one kit each

  1. Core temperature sensor

    Worn on the chest. Estimates core temperature (36 to 42 °C) from heat flux, skin temperature and heart rate; heart rate on its own already tracks core temperature closely enough to indicate heat strain at work.26 Fitted at check-in, so it has settled before stepping starts: settling takes up to 15 minutes, usually less.

    How close it reads

    Manufacturer's data: 0.21 °C mean absolute deviation and 95 % limits of agreement of ±0.55 °C, as quoted in an independent study.19 Not peer reviewed.

    Independent studies: about ±0.6 °C against rectal temperature,14 around 0.3 °C below ingested temperature pills, a validated reference,16,17,21 and further below as core temperature rises.14,15,18 A 2026 review calls heat-flux sensors practical to wear but limited in absolute accuracy.20

    Oral readings: no field method reads deep-body temperature exactly. In exercise studies in the heat, oral readings sat about 0.9 to 1.7 °C below rectal temperature.22,23

    That is why the estimate is shown as a trend beside your oral readings, never as the result.

  2. Heart-rate chest strap

    Read every second, shown live, and linked to the worker's core sensor before screening starts.

Per room, one set

  1. Recording unit

    Hears every sensor and records on the spot. Battery-backed, and restarts by itself after a power cut.

  2. Room conditions sensor

    Air temperature to ±0.1 °C and humidity to ±1 % RH every 10 seconds, with wet bulb calculated.33 WBGT, the international screening index for heat stress, also needs a globe temperature,5,6 so a black-globe thermometer is optional where radiant heat matters. Heat stress meters vary in accuracy against a reference instrument,34 and the guideline asks for monthly checks of the chamber's instruments.1

  3. Calibrated connected scale

    One shared scale, reading to 0.1 kg. Weigh-in and weigh-out give sweat loss by the standard method.31

  4. Live view

    A tablet or wall screen with one tile per worker, the room conditions and the test clock.

The room system is designed for

  • Up to 50workers per session
  • 2 sfrom sensor to live view
  • 10 sat most between each sensor's readings
  • 8 hof continuous running

A report your OMP can sign

Every test produces a report your occupational medical practitioner can sign and file, kept with the worker's earlier tests. The decision stays with them.

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

  • 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.

  • 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.

  • 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.4 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,4 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.3

From set-up to support, one team

You don't buy parts and assemble a system. We bring everything, set it up to your code of practice and stay with you.

  1. Site visit

    We see your chamber, your code of practice and your systems, then size the kit and the reports to them.

  2. Pilot

    We run alongside your current process on real screening days, so your team can compare like for like.

  3. Full roll-out

    Sensors, straps, scales and room sensors installed and checked. Temperature lines, test length and report wording set to your site's approved code, not ours. Test supervisors and occupational health staff trained hands-on.

  4. Connected

    Outcomes to your occupational health, HR or access-control systems, CSV exports for your audits, and ongoing support so screening days aren't held up.

Research and references

The laws, standards and peer-reviewed studies behind what this page says, grouped by topic. Numbers in the text link here, and every entry links to its source.

Law, standards and guidance

  1. 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: the test protocol, room conditions recorded every five minutes, oral thermometers checked by an accredited institution, monthly internal audits of the chamber's instruments and a yearly independent audit of the whole facility. Guideline (PDF)

  2. Department of Employment and Labour (2025) — Physical Agents Regulations, 2024. GN R.5952, Government Gazette 52226, 6 March 2025. For workplaces outside mining: a heat stress action level of 27 °C WBGT, a one-hour average exposure limit of 30 °C WBGT, and documented medical screening where the risk assessment shows the need, at intervals of no more than 24 months. Regulations (PDF)

  3. 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

  4. 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)

  5. NIOSH: Jacklitsch et al. (2016) — Criteria for a recommended standard: occupational exposure to heat and hot environments. DHHS (NIOSH) Publication No. 2016-106. National Institute for Occupational Safety and Health, Cincinnati. Indoor WBGT as 0.7 × natural wet bulb + 0.3 × globe temperature, medical evaluations before and during work in heat, and heat tolerance starting to deteriorate once fluid loss passes 1.5 to 2 % of body weight. CDC (PDF)

  6. ISO 7243:2017 — Ergonomics of the thermal environment: assessment of heat stress using the WBGT (wet bulb globe temperature) index. International Organization for Standardization, Geneva. The WBGT index as a screening method for heat stress at work, over a working day of up to 8 hours. iso.org

  7. World Health Organization and World Meteorological Organization (2025) — Climate change and workplace heat stress: technical report and guidance. WHO and WMO, Geneva, 22 August 2025. Workplace heat stress as a growing challenge, and occupational heat action programmes that assess the worker, the environment and the task. who.int

The screening test, its history and today's practice

  1. 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. In the older four-hour test, pass rates fell from 85 % to 35 % as wet bulb rose from 29 to 31.7 °C. CSIR ResearchSpace (PDF)

  2. 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 and the climatic-room acclimatisation of new workers to the 30-minute screening test. PMC5198811 · doi:10.1080/23328940.2016.1240749

  3. Schutte, Kielblock, de Villiers & Dias (2002) — A pilot study to assess the heat tolerance of female miners. Final report, SIMRAC project Health 817. CSIR Mining Technology, March 2002. The 30-minute screening test judged on oral temperature, used because workers resisted more accurate indicators such as rectal temperature and heart rate, and a 10-minute, 54 W step test whose end heart rate estimates aerobic capacity. MHSC (PDF)

  4. Kielblock (2012) — 'Fitness for work': an eclectic perspective of its application in the South African mining industry. Occupational Health Southern Africa 18(5):16–21. Mine occupational health centres evaluating at least 50 to 100 prospective and in-service employees a day, with heat tolerance screening well established in the industry. Occupational Health Southern Africa (PDF)

  5. CSIR (2024) — Heat stress management services for healthier and safer mining. CSIR Future Production: Mining. Heat tolerance screening training, assessment and auditing services for the South African mining industry. CSIR (PDF)

  6. 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

Estimated core temperature

  1. 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: 95 % limits of agreement of about ±0.6 °C at 31 °C, with core temperatures above 39.5 °C underestimated. PMC8434645 · doi:10.3390/s21175932

  2. 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 below the pill in every session, and further below as core temperature rose. PubMed 36939844 · doi:10.1080/17461391.2023.2193953

  3. Jolicoeur Desroches et al. (2023) — CORE™ wearable sensor: comparison against gastrointestinal temperature during cold water ingestion and a 5 km running time-trial. Journal of Thermal Biology 115:103622. Before a 5 km time trial at 30 °C the estimate read 0.30 °C below an ingested pill, and it underestimated how fast core temperature rose. PubMed 37352596 · doi:10.1016/j.jtherbio.2023.103622

  4. Priego-Quesada et al. (2025) — Effect of aerobic fitness on the validity of the Calera Research™ sensor to estimate core temperature during exercise. Journal of Thermal Biology 127:104067. During ramp exercise at 22 °C the estimate read about 0.3 °C below ingestible pills. doi:10.1016/j.jtherbio.2025.104067 · PubMed 39923389

  5. van den Bogaard et al. (2026) — Responsiveness of the CALERA Research Sensor to heat-acclimation-induced reductions in rectal temperature. Journal of Thermal Biology 140:104541. In controlled hyperthermia the estimate underestimated the time spent at a rectal temperature of 38.5 °C or more, with wide limits of agreement. PubMed 42462462 · doi:10.1016/j.jtherbio.2026.104541

  6. Goulet et al. (2026) — Validity of the CORE wearable sensor during internal cooling induced by hyperhydration with cold water at rest. Sensors 26(16):5042. Quotes the manufacturer's specification (a 36 to 42 °C range, 0.21 °C mean absolute deviation and ±0.55 °C 95 % limits of agreement), and found the estimate showed about 0.1 °C of a 0.76 °C fall in core temperature after cold water at rest. PMC13517099 · doi:10.3390/s26165042

  7. Hashimoto (2026) — A comprehensive review of non-invasive core body temperature measurement techniques. Sensors 26(3):972. Heat-flux sensors are practical to wear but limited in absolute accuracy and no replacement for reference methods; sweating and skin blood flow during exercise add error. PMC12900156 · doi:10.3390/s26030972

  8. Byrne & Lim (2007) — The ingestible telemetric body core temperature sensor: a review of validity and exercise applications. British Journal of Sports Medicine 41(3):126–133. Ingestible telemetric pills as a valid index of core temperature during exercise. PMC2465229 · doi:10.1136/bjsm.2006.026344

  9. Ganio et al. (2009) — Validity and reliability of devices that assess body temperature during indoor exercise in the heat. Journal of Athletic Training 44(2):124–135. During exercise in a 36 °C chamber, oral, aural and axillary readings were not valid estimates of rectal temperature; oral read about 0.9 to 1.1 °C low. PMC2657027 · doi:10.4085/1062-6050-44.2.124

  10. Casa et al. (2007) — Validity of devices that assess body temperature during outdoor exercise in the heat. Journal of Athletic Training 42(3):333–342. Outdoors in the heat, oral, aural and axillary readings differed significantly from rectal temperature; oral read about 1.2 to 1.7 °C low. PMC1978469

Heart rate and heat strain

  1. Moran, Shitzer & Pandolf (1998) — A physiological strain index to evaluate heat stress. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology 275(1):R129–R134. The Physiological Strain Index, which combines core temperature and heart rate to rate heat strain on a 0 to 10 scale. doi:10.1152/ajpregu.1998.275.1.R129 · PubMed 9688970

  2. Byrne & Lee (2019) — The Physiological Strain Index modified for trained heat-acclimatized individuals in outdoor heat. International Journal of Sports Physiology and Performance 14(6):805–813. The index adapted for heat-acclimatised men running a half-marathon in outdoor heat. doi:10.1123/ijspp.2018-0506 · PubMed 30569782

  3. Buller et al. (2013) — Estimation of human core temperature from sequential heart rate observations. Physiological Measurement 34(7):781–798. A model using heart rate alone kept 95 % of core temperature estimates within ±0.63 °C: a practical indication of thermal work strain, in its authors' words, not a replacement for direct measurement. PubMed 23780514 · doi:10.1088/0967-3334/34/7/781

  4. Gillinov et al. (2017) — Variable accuracy of wearable heart rate monitors during aerobic exercise. Medicine & Science in Sports & Exercise 49(8):1697–1703. During exercise a chest strap agreed with an ECG more closely than wrist-worn optical monitors. PubMed 28709155 · doi:10.1249/MSS.0000000000001284

  5. Machado et al. (2025) — A systematic review of chest-worn sensors in cardiac assessment: technologies, advantages, and limitations. Sensors 25(19):6049. Chest-worn sensors correlate strongly with an ECG at rest and in light to moderate activity; motion, strap placement and sweat are among the limits. PMC12526813 · doi:10.3390/s25196049

  6. Périard, Eijsvogels & Daanen (2021) — Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies. Physiological Reviews 101(4):1873–1979. Core temperature rises, and the body loses water through sweat, during prolonged exercise in the heat. doi:10.1152/physrev.00038.2020 · PubMed 33829868

  7. Périard, Racinais & Sawka (2015) — Adaptations and mechanisms of human heat acclimation: applications for competitive athletes and sports. Scandinavian Journal of Medicine & Science in Sports 25(Suppl 1):20–38. Heat acclimation improves sweating and lowers body temperature and cardiovascular strain. doi:10.1111/sms.12408 · PubMed 25943654

Sweat loss and room conditions

  1. 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. Whole-body sweat loss from the change in body mass before and after exercise, corrected for fluid intake and urine output. PMC5371639 · doi:10.1007/s40279-017-0691-5

  2. Sawka et al. (2007) — American College of Sports Medicine position stand: exercise and fluid replacement. Medicine & Science in Sports & Exercise 39(2):377–390. Sweat rates estimated by weighing before and after exercise. PubMed 17277604 · doi:10.1249/mss.0b013e31802ca597

  3. Stull (2011) — Wet-bulb temperature from relative humidity and air temperature. Journal of Applied Meteorology and Climatology 50(11):2267–2269. Wet bulb calculated from air temperature and relative humidity, with a mean absolute error under 0.3 °C within its stated range. doi:10.1175/JAMC-D-11-0143.1

  4. Cooper et al. (2017) — An evaluation of portable wet bulb globe temperature monitor accuracy. Journal of Athletic Training 52(12):1161–1167. Six commercial heat stress monitors against a reference instrument: accuracy varied between devices, and those using a psychrometric wet bulb tended to read low. PMC5759700 · doi:10.4085/1062-6050-52.12.18

Questions mines ask us

Does this replace our heat tolerance screening protocol?

No. Your test runs as your code of practice sets it out: the same step test, the same oral temperature readings it is judged on and the same decision by your occupational medical practitioner. 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.

What does a pilot involve?

It runs beside your existing screening on real screening days, with nothing paused and your protocol and your occupational medical practitioner's calls unchanged. We provide the equipment and tools to capture your existing readings alongside ours, compare the values side by side with your team, and then you decide whether to go ahead.

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. The manufacturer's own figures, which are not peer reviewed, give 95 % limits of agreement of ±0.55 °C. Independent studies found it can differ from rectal temperature by around 0.6 °C either way, and that it reads lower the higher core temperature climbs. That is why we show it as a trend next to your oral readings, never as the result.

Sources: references 14, 15, 18 and 19.

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.

Sources: references 1 and 9.

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 recording unit is battery-backed and restarts by itself after a power cut, and 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). They set a heat stress action level of 27 °C WBGT and a one-hour average exposure limit of 30 °C WBGT, and call for documented medical screening where the risk assessment shows the need, at intervals of no more than 24 months. A heat test can be one way your occupational health practitioner meets it. In the United States, NIOSH likewise recommends medical evaluations before and during work in heat.

Sources: references 2 and 5.

Next step

An HTS pilot, run in parallel with your existing screening

Tell us how many workers you screen and where you test them. Then we agree a pilot start date, and who runs it on your side.

Talk to us about a pilot

Our commitment

  • Runs beside your existing screening, with nothing paused
  • Your protocol and your OMP's calls stay unchanged
  • We provide the tech and tools to capture your existing readings alongside ours
  • Values compared side by side, then a go or no-go

On our roadmap

Real-time physiological telemetry, building on the same sensors, records and reports. Planned, not available yet.

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