Supervisors and safety staff running crews in Maryland, indoors or out. Maryland Occupational Safety and Health adopted a heat stress standard covering both settings — a broader scope than most US state rules, which are outdoor-only.
Which heat rule applies to this crew, today? In Maryland the state's own standards are the enforceable floor — they are what an inspector cites. Above them sit the federal enforcement posture and the technical standards that contracts and site safety plans commonly adopt.
Declare the worksite as Maryland in the calculator and the composite narrows to exactly this set: a rule binds only where it governs, so Maryland's rules bind here and another state's do not. Rules from elsewhere are still evaluated and shown, marked advisory.
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.
Derived from the registry: every standard declaring US-MD. Wildfire smoke, where the state has a rule, is listed separately below — it is a different hazard axis and never enters the work/rest composite.
| Rule | Authority | Legal status | What it sets |
|---|---|---|---|
| Maryland OSHA Heat Stress Standard (COMAR 09.12.32) | Maryland Occupational Safety and Health (MOSH) | Mandatory regulation | Work/rest limits |
These apply, or are cited, in Maryland as anywhere else in the US. Full national picture: United States country page.
| Rule | Authority | Legal status | What it sets |
|---|---|---|---|
| OSHA Heat National Emphasis Program (CPL 03-00-024, April 2026) | US OSHA, Directorate of Enforcement Programs | Guidance — voluntary | Alert levels |
| OSHA Federal Heat Rule NPRM (Proposed) | US OSHA | Proposed rule — not yet enforceable | Control measures |
| NIOSH 2016-106 Table 6-2 | NIOSH | Guidance — voluntary | Work/rest limits |
| NIOSH REL/RAL Logarithmic Curve | NIOSH | Guidance — voluntary | Screening thresholds |
| ACGIH TLV / Action Limit | ACGIH | Technical standard — not law unless adopted or incorporated | Work/rest limits |
| La Isla Network-informed RSH-s Default Protocol | La Isla Network / Adelante Initiative | Industry guidance — voluntary | Work/rest limits |
A grounds-maintenance crew outside Baltimore in July: 32°C air at 60% relative humidity (a heat index near 99°F, Maryland’s high-heat band), a site WBGT of 30°C, moderate work, and an acclimatized crew, with the worksite declared as Maryland. Maryland’s rule reads heat index and, unlike most US state rules, covers indoor workplaces as well as outdoor ones.
Inputs: air temperature 32°C · 60% relative humidity · WBGT 30°C · moderate work (300 W) · acclimatized worker · worksite declared in US-MD
| Rule | What it returns at these inputs |
|---|---|
| Maryland OSHA Heat Stress Standard (COMAR 09.12.32) | 50 / 10 min work/rest per hr |
| La Isla Network-informed RSH-s Default Protocol | 40 / 20 min work/rest per hr |
| ACGIH TLV / Action Limit | 30 / 30 min work/rest per hr |
| NIOSH REL/RAL Logarithmic Curve | 28.2°C limit — exceeded |
Answer for this shift: 30 / 30 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.