Crew leads and foremen
- Check the number before the crew starts and when it feels like it has turned.
- OSHA mode gives occupational guidance rather than athletic thresholds.
Most organisations that take heat seriously end up owning one or two WBGT instruments. That is the right start and it has a structural limit: the instrument is in one place, usually where it was last left, and the decisions are being made in a dozen others.
The supervisor on the far side of the site, the crew lead who just arrived from another job, the scheduler deciding tomorrow's sequence at six in the morning. None of them are standing next to the instrument, and all of them are making heat decisions.
What an app adds to an instrument
Coverage
Every supervisor has the reading, not just whoever is near the device. Crews on separate sites get a reading for their own location.
Forecast
An instrument tells you now. Planning requires knowing what three in the afternoon looks like, or Thursday.
No calibration or wick
Nothing to maintain, re-wet, or discover has been sitting dry in a truck since June.
Any location
Check a site you have not mobilized to yet, or a city a crew is travelling to next week.
What an app does not replace
Being straight about this matters more than the sale. A weather-derived WBGT describes the ambient environment at your coordinates. It does not know you are in a trench, on a dark roof, beside a running compressor or inside impermeable coveralls, and each of those can be worth several degrees.
Where a standard, a contract or a client specification requires on-site measurement, measure on site. The honest division of labour is this: the app for planning, scheduling, awareness and cross-checking, and the instrument for the compliance reading and for any location with a known hot spot.
Used together they cover each other's weaknesses. The instrument gives you the authoritative number where it stands; the app gives everyone else a usable number everywhere else.
Who on a crew uses it
Schedulers and project managers
- Sequence heavy work into the cooler hours using the 14-day forecast.
- Decide a week out whether a pour or a tear-off needs an earlier start.
Safety managers
- A consistent calculation across every crew, so readings mean the same thing site to site.
- Check conditions at a site without driving to it.
Workers themselves
- Seeing the number makes the rules make sense, and makes speaking up easier.
- Free to download, so there is nothing to procure or issue.
Rolling it out
- Decide and write down which decisions use the app and which require the instrument. Ambiguity here is where programs get into trouble.
- Have supervisors install it before the season, not during the first heat wave.
- Set OSHA mode as the default so nobody is reading athletic thresholds against industrial work.
- Keep the equipment and clothing adjustment with the trigger table, since the app reports ambient WBGT and the adjustment is yours to apply.
- Keep logging. The app does not replace your records, and the records are what demonstrate the program ran.
Warning signs of heat illness
Heat stress shows up before it becomes an emergency. Anyone on site should speak up immediately on any of these:
Dizziness or lightheadedness
Nausea or vomiting
Chills or goosebumps in the heat
Severe or throbbing headache
Confusion or out-of-character behavior
Stumbling, cramping or collapse
When in doubt, cool first and call for help. Collapse or confusion in the heat should be treated as possible exertional heat stroke: begin cold-water immersion immediately and call 911. Cooling comes before transport.
Free on iPhone, for the whole crew
No procurement, no per-seat licence and nothing to issue. Supervisors install it themselves and have the same number you do.
- OSHA mode with occupational thresholds
- WBGT for your site or any city
- Hourly and 14-day forecasts for scheduling
- Humidity, wind, sun and cloud behind every reading
WBGT is estimated from weather data with the peer-reviewed Liljegren model. Where a policy requires on-site measurement, use the app for planning and as a cross-check alongside your instrument.
Common questions
Is there a good workplace heat app?
The WBGT app includes an OSHA mode with occupational rather than athletic thresholds, gives live WBGT for any location, and forecasts it hourly and out to 14 days for shift planning. It is free to download on iPhone.
Can an app replace a WBGT instrument?
Not for compliance readings or for known hot spots. An app computes WBGT for ambient conditions at your coordinates and cannot see a trench, a dark roof or a hot process nearby. Use it for planning, awareness and cross-checking, and the instrument where measurement is required.
How accurate is an app-based WBGT reading?
The app runs the peer-reviewed Liljegren physical model on live weather data, which is the accepted method for estimating WBGT from meteorological inputs. The limitation is not the model; it is that local microclimates differ from ambient conditions.
Does it work for multiple crews across different sites?
Yes, and that is the main advantage over a single instrument. Each supervisor gets a reading for their own location, computed the same way, so numbers are comparable across a project.
Does an app satisfy OSHA?
There is no app that makes an employer compliant. What matters is the program: measurement, trigger levels, water, shade, acclimatization, training, emergency response and records. An app helps you run it; see OSHA WBGT.
Related WBGT guides
Know the real heat number
Real-time WBGT, flag levels and forecasts. Free on iPhone.
