MINNESOTA · MINN. R. 5205.0110

Minnesota's Indoor Heat Stress Standard Is WBGT-Based. HeatShield Is Built Around It.

Q: Do I need physical sensors for indoor WBGT monitoring in Minnesota?

For accurate indoor WBGT calculation, yes — you need real temperature and humidity readings from inside the facility. HeatShield's PRO-tier Sensor API Integration accepts live readings from any WiFi-capable sensor hardware that can POST temperature and humidity data to a custom HTTP endpoint. No proprietary hardware lock-in required. Without a sensor, HeatShield's compliance framework, threshold documentation, and acclimatization tracking are still fully functional.

Minnesota's indoor heat stress regulation under Minn. R. 5205.0110 sets WBGT-based exposure limits for warehouses, manufacturing, food processing, and any indoor workplace where heat is a hazard. HeatShield handles the monitoring, acclimatization tracking, documentation, and training that MNOSHA requires, with live sensor data for accurate indoor WBGT calculation. Outdoor crews are covered too via OSHA's General Duty Clause.

Aligned with Minn. R. 5205.0110, Minnesota's WBGT-based indoor heat stress standard

PRO: Connect physical sensors for live indoor WBGT data (Sensor API Integration)

Per-worker acclimatization tracking, critical in Minnesota's variable climate

Documented training with certificates of completion

Weekly supervisor review, logged as a tamper-evident compliance record

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WHAT MNOSHA REQUIRES

Minnesota Has a WBGT Standard for Indoor Work, and the General Duty Clause Covers Everyone Else.

Minn. R. 5205.0110: Indoor Heat Stress Standard

Applies to Indoor Workplaces Where Heat Exposure Is a Hazard

Minnesota's heat stress standard is an indoor regulation enforced by MNOSHA under the state's OSHA-approved plan. It uses Wet Bulb Globe Temperature (WBGT) as the measurement standard and sets two-hour time-weighted exposure limits based on work intensity. Key requirements:

WBGT-based exposure limits: limits are set by work intensity; heavy work triggers protections at lower WBGT values than light or moderate work
Hydration and rest: documented provision of water and rest breaks calibrated to heat conditions and workload intensity
Acclimatization plan: documented protocol required for new and returning workers; Minnesota's variable climate makes acclimatization especially difficult to maintain
Training: supervisors and workers must be trained to recognize heat illness symptoms, prevention methods, and emergency response
Engineering and administrative controls: employers must implement controls to reduce heat exposure before relying on administrative measures alone
Documentation: records of monitoring activity, incidents, and corrective actions must be maintained for inspection

OSHA General Duty Clause: Outdoor Workplaces

Outdoor Minnesota Workers Are Covered Too, Even Without a State Outdoor Standard

Minn. R. 5205.0110 covers indoor workplaces. But Minnesota employers with outdoor crews (construction, landscaping, agriculture, municipalities) face the same enforcement risk as employers in states with explicit outdoor standards. OSHA's General Duty Clause requires all employers to protect workers from recognized hazards, and heat is a recognized hazard. MNOSHA enforces this actively. Key outdoor requirements:

Heat monitoring: outdoor conditions must be tracked when heat exposure is a recognized hazard
Water and rest: cool water and rest breaks must be provided based on heat conditions and workload
Acclimatization: new and returning outdoor workers require documented acclimatization management
Written program: a documented heat illness prevention program is expected under enforcement
Training: supervisors and outdoor workers must be trained on heat illness recognition and emergency response

Outdoor monitoring: automatic via weather data, no hardware required)

Plain-language overview only. Not legal advice. Consult qualified legal counsel for program-specific guidance.

The HeatShield Solution

Every MNOSHA Heat Requirement. Mapped to a HeatShield Feature.

MNOSHA Requirement	Regulation	How HeatShield Handles It	Documentation Produced
WBGT-based indoor heat monitoring	Minn. R. 5205.0110	PRO Sensor API Integration connects physical hardware for live indoor readings; HeatShield calculates WBGT in real time using temperature, humidity, radiant heat, and air movement	Timestamped WBGT monitoring log per site
Exposure limit thresholds by work intensity	Minn. R. 5205.0110	Configurable thresholds per site based on workload type; alerts fire when exposure limits are approached or crossed	Threshold crossing log with conditions and timestamps
Acclimatization monitoring	Both	Per-worker acclimatization status tracked from first day; risk thresholds adjusted for workers in observation window	Worker acclimatization records per site
Supervisor & worker training	Both	Built-in LMS with heat illness prevention course; bilingual (EN/ES)	Certificates of completion per employee
Outdoor monitoring (General Duty)	Gen. Duty	Automated outdoor monitoring pulls live weather data; configurable thresholds per outdoor site; acclimatization tracking applies equally	Outdoor monitoring log with timestamped threshold events
Written Heat Illness Prevention Program	Both	Auto-generated compliance documentation for your org and every site	Export-ready PDF for inspection
Emergency response plan access	Both	Response steps surfaced during high-heat events; logged per monitoring session	Emergency procedure acknowledgment log

Minn. R. 5205.0110: Acclimatization

Minnesota's Climate Makes Acclimatization Harder and More Important to Track.

MNOSHA specifically calls out acclimatization as one of the two most important methods of preventing heat disorders, alongside hydration. Minnesota's highly variable climate, where daily high temperatures can swing 30°F from one day to the next, means workers often cannot become and stay acclimatized the way workers in consistently hot climates can. That makes per-worker tracking essential, not optional.

30°F

Daily Swing

Minnesota summer temperatures can vary 30°F from day to day, preventing workers from staying acclimatized the way they would in consistently hot climates.

Days Off

Workers returning after 5 or more days away from heat exposure must restart the acclimatization observation period, even experienced workers.

2×

Higher Risk

Heat illness risk is significantly elevated during the acclimatization window. HeatShield adjusts alert thresholds for at-risk workers automatically.

👷

Per-Worker Status Tracking

Each worker's acclimatization start date is recorded. HeatShield automatically identifies who is in the at-risk observation window at any given time, with no spreadsheets required.

🌡️

Adjusted Risk Thresholds

Heat stress risk scores factor in acclimatization status. Workers in the observation window trigger supervisor alerts at lower thresholds than fully acclimated crew members.

📋

Documented for Inspection

Acclimatization records are stored per worker and exportable as part of your compliance packet, showing MNOSHA exactly which workers were in observation, and when.

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Automatic Reset on Return

When a worker returns after 5+ days away, HeatShield automatically flags them as re-entering the acclimatization window, with no manual tracking required from supervisors.

Sensor API Integration (PRO)

Minnesota's Standard Is WBGT-Based. Accurate WBGT Requires Real Sensor Data.

WBGT is not a number your weather app provides. For indoor sites, accurate WBGT calculation requires actual temperature and humidity readings from inside the facility, not outdoor weather station estimates. That's what the PRO-tier Sensor API Integration delivers: your physical hardware POSTs live readings directly to HeatShield, which uses them to calculate WBGT and determine threshold status in real time.

Admins manage and rotate API keys per site from within the dashboard. The staleness indicator shows when a reading was last received, so you always know the data is fresh.

Works with any WiFi-capable sensor that supports custom HTTP POST endpoints
Per-site API key, issued, managed, and rotatable by admins
Live reading and staleness status displayed in the HeatShield UI
Works with any sensor hardware that can POST temperature and humidity data to a custom HTTP endpoint
Feeds live data into WBGT calculation, with no static indoor temp assumptions

WBGT

Moderate Work: Exposure Limit Active

Threshold based on work intensity level Rest periods & hydration required Supervisor alert with timestamp

Heavy

Heavy Work: Lower WBGT Threshold

Heavy work triggers limits at lower WBGT values Enhanced rest & supervisor observation required

Minnesota's standard sets limits by work intensity, not a single fixed temperature.

Industries We Serve

If Your Minnesota Workers Are Exposed to Heat, Indoor or Outdoor, You Have a Compliance Obligation.

🏭

Warehousing & Distribution

Warehouse distribution centers, fulfillment operations, and logistics facilities. Indoor heat stress in large warehouse spaces is a year-round issue, not just a summer problem. HeatShield monitors WBGT per site using live sensor data, tracks acclimatization for new and returning workers, and keeps your MNOSHA documentation inspection-ready.

⚙️

Manufacturing & Food Processing

Manufacturing plants, meatpacking facilities, commercial kitchens, and food processing operations. These environments generate significant radiant heat from machinery and cooking equipment, creating conditions where WBGT diverges substantially from simple thermometer readings. HeatShield's WBGT calculation accounts for radiant heat, giving you an accurate picture of actual worker heat stress.

🏗️

Construction & Landscaping

Outdoor crews in construction, landscaping, and municipal operations. Minnesota's variable summer climate, with temperature swings of 30°F or more from day to day, means outdoor workers frequently face heat conditions before they're acclimatized. HeatShield tracks outdoor conditions automatically and flags acclimatization risk per worker, keeping you defensible under the General Duty Clause.

🌾

Agriculture

Farms, processing facilities, greenhouses, and field operations. Outdoor agricultural workers face real heat stress risk during Minnesota summers, and MNOSHA's General Duty Clause enforcement applies regardless of whether a state outdoor heat standard is codified. HeatShield automates monitoring and produces the documentation your program requires.

Documentation

What Gets Documented. Automatically. Every Day.

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Every monitoring event

Date, time, site, WBGT reading, and risk level, logged automatically for every check-in, indoor and outdoor

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Every alert sent

Recipient, channel (SMS/push), delivery status, and triggering condition, documented at the moment it's sent

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Every threshold crossed

WBGT exposure limit events are timestamped and tied to a specific site, workload type, and monitoring record

👷

Worker acclimatization status

Who was in the observation window, when it started, and how risk alerts were adjusted for at-risk workers

🎓

Training completions

Employee name, course, completion date, and certificate of completion, stored per worker, exportable on demand

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Compliance packet export

One-click PDF covering your full monitoring, alert, acclimatization, and training history, formatted for MNOSHA inspection

MNOSHA inspectors want to see your records on demand. HeatShield builds them in the background automatically.

Frequently Asked Questions

What Minnesota Employers Ask Before Starting a Trial

What is Minnesota's heat stress standard and who does it apply to?

Minnesota's heat stress standard under Minn. R. 5205.0110 applies to indoor places of employment where heat exposure is a recognized hazard. It uses WBGT as the measurement standard and sets two-hour time-weighted exposure limits based on work intensity. Industries most commonly affected include warehouses, distribution centers, manufacturing, food processing, commercial kitchens, and laundries.

Why does Minnesota use WBGT instead of a simple temperature number?

WBGT accounts for four factors that determine actual heat stress: air temperature, humidity, radiant heat, and air movement. Simple thermometer readings miss radiant heat from machinery, poor ventilation, and humidity, all of which significantly affect worker heat stress in indoor environments. Minnesota's standard uses WBGT because it reflects real conditions more accurately than dry-bulb temperature alone.

What is acclimatization and why is it especially important in Minnesota?

Acclimatization is the physical process by which a worker's body adapts to heat exposure over time. MNOSHA specifically highlights acclimatization as one of the two most important prevention methods. Minnesota's variable summer climate, with swings of up to 30°F from day to day. This means workers frequently cannot stay acclimatized between heat exposures. HeatShield tracks each worker's status automatically and adjusts alert thresholds for at-risk workers.

Do I need physical sensors for indoor WBGT monitoring?

For accurate indoor WBGT calculation. Yes, you need real temperature and humidity readings from inside the facility. HeatShield's PRO-tier Sensor API Integration lets your existing WiFi-capable hardware POST live readings directly to HeatShield. HeatShield works with any WiFi-capable sensor hardware that can POST temperature and humidity readings to a custom HTTP endpoint — no proprietary hardware lock-in required. Without a sensor, HeatShield's compliance framework, threshold documentation, and acclimatization tracking are still fully functional.

Are my outdoor workers covered by Minn. R. 5205.0110?

No. Minn. R. 5205.0110 covers indoor workplaces only. However, Minnesota employers with outdoor crews are covered by OSHA's General Duty Clause, which requires all employers to protect workers from recognized hazards. Heat is a recognized hazard, and MNOSHA enforces this actively. HeatShield's outdoor monitoring pulls live weather data automatically, with no hardware required, and applies the same acclimatization tracking and documentation to outdoor sites.

We have multiple facilities across Minnesota. Can HeatShield handle all of them?

Yes. HeatShield supports unlimited sites on every plan at no extra cost per site. Each facility gets its own monitoring configuration, alert history, and compliance documentation, all accessible from a single account. Indoor and outdoor sites can be mixed freely.

What does MNOSHA want to see during a heat-related inspection?

Inspectors typically ask for: (1) evidence of WBGT monitoring at affected sites, (2) documentation that exposure limits were tracked and acted on, (3) acclimatization records for new and returning workers, (4) proof that supervisors and workers were trained, and (5) records of corrective actions taken when thresholds were crossed. HeatShield produces all of this automatically and stores it in an exportable compliance packet.

Built-In Compliance Training

Monitoring Proves the Conditions. Training Proves Your Crew Was Ready.

MNOSHA doesn't just want to see that you were watching the temperature. They want evidence that your workers knew what to do when it got dangerous.

HeatShield includes a built-in, OSHA-aligned heat illness prevention training course — assigned and completed directly through the platform. Certificates of completion are stored per worker and included in your compliance records.

✓ 11-lesson course covering heat illness prevention for employees and supervisors
✓ Accessible on any phone — no app download required
✓ Progress tracked per worker
✓ Certificates of completion stored and exportable
✓ Included with every plan

PRICING

Plans built for field operations

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Core

Structured monitoring for small crews

$ 39 /mo

Billed $468 annually

Unlimited jobsites & monitoring
Automated heat monitoring & risk transitions
Supervisor notifications & escalation
Crew management
Mobile-first PWA experience
Site Groups
12-month data retention
Standard PDF export
10 training seats included*
Standard support
* $10/seat for additional users

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Pro

Extended Records, Reporting, Training & Indoor Sensor API

$ 59 /mo

Billed $708 annually

Everything in Core, plus:
Compliance Packet Downloads
Jobsite Templates
Sensor API Integration Indoor
Incident Reporting
Extended data retention (36 months)
PDF + CSV exports
20 training seats included*
Priority support
* $5/seat for additional users