Corporate EHS leads, contractors, and programme managers responsible for crews in more than one country — where "our heat policy" has to survive contact with a Gulf midday ban, an EU member state's own decree, and a US state standard, all at once.
Which heat rule applies to this crew, today? Across borders the answer turns on three distinctions this calculator enforces rather than blurs:
Where two standards conflict, this calculator takes the more protective limit and shows you both, rather than reconciling them silently.
Legal status below is the registry's own legalStatus field for each rule. A "mandatory regulation" is enforceable law in its jurisdiction; everything else is guidance, a technical standard, or a proposal, and binds you only if your contract, your client, or your own programme adopts it.
These claim no country and therefore bind anywhere, including where nothing local exists.
| Rule | Authority | Legal status | What it sets |
|---|---|---|---|
| La Isla Network-informed RSH-s Default Protocol | La Isla Network / Adelante Initiative | Industry guidance — voluntary | Work/rest limits |
| ACGIH TLV / Action Limit | ACGIH | Technical standard — not law unless adopted or incorporated | Work/rest limits |
| NIOSH 2016-106 Table 6-2 | NIOSH | Guidance — voluntary | Work/rest limits |
| NIOSH REL/RAL Logarithmic Curve | NIOSH | Guidance — voluntary | Screening thresholds |
| ISO 7243:2017 WBGT Screening | ISO | Technical standard — not law unless adopted or incorporated | Screening thresholds |
| ISO 7933 Predicted Heat Strain (PHS) | ISO | Technical standard — not law unless adopted or incorporated | Work/rest limits |
| TB MED 507 Heat Categories | US Army / Air Force | Technical standard — not law unless adopted or incorporated | Work/rest limits |
A framework duty with no number of its own: it obliges risk assessment and control, and the member state’s own rule supplies the threshold.
| Rule | Authority | Legal status | What it sets |
|---|---|---|---|
| EU Framework Directive 89/391/EEC | European Union | Mandatory regulation | Control measures |
Calendar- and clock-driven stop-work rules rather than WBGT thresholds — they prohibit outdoor work in a fixed window during a fixed season, irrespective of the day’s reading.
| Rule | Authority | Legal status | What it sets |
|---|---|---|---|
| Qatar Ministerial Decision No. 17 of 2021 | Qatar Ministry of Labour | Mandatory regulation | Stop-work / banned hours |
| UAE Midday Break Rule | UAE Ministry of Human Resources | Mandatory regulation | Stop-work / banned hours |
| Saudi MHRSD Heat Stress Rule | Saudi Ministry of Human Resources and Social Development | Mandatory regulation | Work/rest limits |
| Kuwait Noon Work Ban | Kuwait Public Authority for Manpower | Mandatory regulation | Stop-work / banned hours |
| Oman Midday Work Ban | Oman Ministry of Labour | Mandatory regulation | Stop-work / banned hours |
| Bahrain Midday Outdoor Work Ban | Bahrain Ministry of Labour | Mandatory regulation | Stop-work / banned hours |
Sector protocols that follow the operation across borders, and are commonly written into supply-chain or event contracts.
| Rule | Authority | Legal status | What it sets |
|---|---|---|---|
| Better Work / GLI Apparel Heat Overlay | ILO Better Work / IFC / Cornell GLI | Industry guidance — voluntary | Alert levels |
| Oil & Gas Heat Governance Overlay | IOGP / IPIECA-style governance | Industry guidance — voluntary | Control measures |
| FIFA / Sports Hydration Break Overlay | FIFA / sports medicine guidance | Industry guidance — voluntary | Alert levels |
| AAFA Guide to Protecting Workers from Heat Stress 2026 | AAFA | Industry guidance — voluntary | Work/rest limits |
The same crew, the same WBGT of 32°C, the same heavy workload, the same acclimatized state — but no worksite country has been declared. Only the jurisdiction-neutral layer can bind, and this is what a global corporate floor looks like before any national rule is added on top. Declare a country in the calculator and the answer can only get stricter, never looser.
Inputs: WBGT 32°C · heavy work (415 W) · acclimatized worker · no worksite country declared
| Rule | What it returns at these inputs |
|---|---|
| La Isla Network-informed RSH-s Default Protocol | 20 / 40 min work/rest per hr |
| ACGIH TLV / Action Limit | 15 / 45 min work/rest per hr |
| NIOSH REL/RAL Logarithmic Curve | 26.6°C limit — exceeded |
| ISO 7243:2017 WBGT Screening | 26°C limit — exceeded |
| TB MED 507 Heat Categories | 20 / 40 min work/rest per hr |
Answer for this shift: 15 / 45 min work/rest per hr (most protective)
Every value above is computed at build time by the same engine the live calculator runs — the single most protective applicable result, never an average across standards. Change any input and the answer changes, which is what the calculator is for.
Screening-level guidance. This tool provides screening-level heat guidance for planning. It is a decision-support instrument, not a sole compliance authority or a medical prescription. Verify against the governing standard for your jurisdiction and consult a qualified professional for individual medical decisions.