Minnesota indoor temperature records
WBGT heat limits by workload plus cold-workroom minimums under Minn. R. 5205.0110.
Minnesota is the one rule where workload changes the number. Indoor heat limits are set in wet bulb globe temperature: 77 F for heavy work, 80 F for moderate, and 86 F for light. The same rule sets floors for cold workrooms. Without a recorded workload, a WBGT reading cannot be evaluated at all, because 82 F is fine for light work and over the limit for heavy work in the same building.
Takeaways
- Record workload alongside every indoor Minnesota reading.
- Say which WBGT limit applies to a given crew.
- Understand why WBGT is not the same as temperature or heat index.
- Apply the cold-workroom minimums, which most heat guides ignore.
Workload is part of the reading
What WBGT is, and what it is not
The cold workroom minimums
What a Minnesota indoor log should contain
Frequently asked questions
- Can I use heat index instead of WBGT? Not for the Minnesota limits, which are written in WBGT. Heat index does not account for radiant heat or air movement, so it can read comfortable in a space that exceeds the WBGT ceiling.
- Where do I take the reading? Where the work happens, at roughly the height of the work. A reading taken by the door of a foundry does not describe conditions at the furnace.
- What if the crew does heavy and light work in the same shift? Apply the limit for the heaviest sustained work in the period you are evaluating. If the crew shovels for two hours and then does paperwork, the shoveling period is the one that matters.
- Does this apply to outdoor work in Minnesota? No. Minn. R. 5205.0110 is an indoor workroom standard. Outdoor work in Minnesota falls under the federal general duty clause and the heat National Emphasis Program.