European Unions Push for WBGT-Based Heat Rules

Why WBGT Is the Standard for Measuring Worker Heat Stress

European trade unions have drafted new legislation that would give millions of outdoor and indoor workers an enforceable right to stop working when heat becomes dangerous, and the threshold they're proposing isn't based on air temperature at all. It's based on Wet Bulb Globe Temperature, or WBGT, the same heat stress measurement increasingly used by safety regulators, athletic programs, and militaries around the world.

The push comes from a coalition of union federations representing roughly 15 million workers, who want the heat protections folded into the EU's upcoming Quality Jobs Act, expected to reach parliament by the end of 2026. The timing isn't coincidental. The EU's Copernicus climate monitoring service confirmed that June 2026 was the hottest June on record in western Europe, with temperatures in the Netherlands reaching 39°C during the month's heatwave.

What the Draft Directive Would Require

The proposed rules would require employers to guarantee outdoor workers access to shade, water, and other cooling methods, introduce regulated heat breaks, and adjust working hours to avoid the hottest part of the day. The centerpiece, though, is an enforceable upper temperature limit tied to WBGT rather than simple air temperature.

Under the draft, work intensity would begin slowing once WBGT reaches 30°C, continuing to scale back as conditions worsen. Once WBGT exceeds 32.5°C, workers would be permitted to stop entirely. That two-tier structure - slow down, then stop - mirrors the graduated, flag-based systems already used in sports medicine and by several U.S. state and military heat safety programs, rather than a single all-or-nothing cutoff.

Why Unions Are Pushing WBGT Specifically

The reasoning behind choosing WBGT over ordinary temperature is the same argument occupational safety researchers have made for decades: a thermometer reading alone doesn't capture what a worker's body actually experiences. WBGT combines four factors - air temperature, humidity, radiant heat from the sun, and wind speed - into a single reading that reflects real physiological heat stress, not just how warm the air happens to be.

That distinction matters enormously for outdoor labor. A construction worker standing on hot asphalt in direct sun faces a dramatically different heat load than a weather station reading would suggest, even at an identical air temperature. Humidity slows the body's ability to cool itself through sweat evaporation, and radiant heat from pavement, machinery, or direct sunlight adds a load that a shaded thermometer simply never measures. WBGT accounts for all of it, which is exactly why unions are asking regulators to anchor enforcement to it instead of a number pulled from a weather app.

The Scale of the Problem

The push for binding rules is grounded in sobering numbers. Research from the European Trade Union Institute estimates that roughly 130 million workers across Europe face workplace heat stress exposure each year, contributing to an estimated 277,000 heat-related injuries and 230 deaths annually. A related survey by the Dutch union CNV found that 52% of workers said heat exposure had damaged their health, 56% reported unsafe working conditions during hot weather, and 44% said they had continued working despite conditions they considered unsafe - while six in ten employers had no heat plan in place at all.

A Familiar Pattern, Playing Out Globally

For anyone following heat safety policy outside Europe, this will look familiar. OSHA's Heat National Emphasis Program, several U.S. state heat standards, and military heat injury prevention guidance have all converged on WBGT as the preferred measurement for the same reason European unions are now proposing it: it's the only common metric that reflects actual environmental heat stress rather than an approximation. The specifics differ - enforcement mechanisms, exact thresholds, and covered industries all vary by jurisdiction - but the underlying logic is consistent worldwide: subjective judgment calls about “how hot it feels” don't hold up as a basis for protecting workers, and WBGT does.

What Employers Can Do Now

Regulation aside, the practical lesson for any organization managing outdoor or high-heat work is the same regardless of which country's rules eventually apply:

1. Measure WBGT on-site rather than relying on a nearby weather station or forecast.
2. Define graduated work-rest thresholds, similar to the EU's slow-down-then-stop model, instead of a single all-or-nothing cutoff.
3. Build in the shade, hydration, and adjusted scheduling that make those thresholds actually achievable, not just written down.
4. Document every threshold crossed alongside the response taken, so the policy holds up under review.

Whether a binding EU directive arrives by the end of 2026 or not, the direction of travel - for regulators, unions, and safety professionals alike - is clearly toward WBGT as the standard measurement for deciding when heat has become too dangerous to keep working through.

Frequently Asked Questions

What are European unions proposing for workplace heat protection?

A coalition of EU trade union federations has drafted a directive that would require employers to provide shade, water, and cooling access, introduce regulated heat breaks, adjust working hours, and set an enforceable WBGT-based limit at which work must slow or stop. Unions want it included in the EU's upcoming Quality Jobs Act.

What WBGT thresholds are being proposed?

The draft proposes that work intensity begin slowing once WBGT reaches 30°C, continuing to scale back as conditions worsen, with workers permitted to stop entirely once WBGT exceeds 32.5°C.

Why use WBGT instead of air temperature to regulate heat exposure?

WBGT combines air temperature, humidity, radiant heat, and wind speed into one reading, reflecting the actual heat stress a body experiences. Air temperature alone misses humidity's effect on sweat evaporation and radiant heat from sun and surfaces, both of which significantly increase real-world heat risk.

How many workers in Europe are affected by workplace heat stress?

Research from the European Trade Union Institute estimates roughly 130 million workers across Europe face heat stress exposure annually, contributing to an estimated 277,000 injuries and 230 deaths each year.

Is WBGT used outside of Europe for worker heat safety?

Yes. WBGT is already central to OSHA's Heat National Emphasis Program, multiple U.S. state heat standards, and military heat injury prevention guidance, reflecting a broader global convergence on WBGT as the standard measurement for occupational heat stress.

Sources:

The Guardian, “Unions in Europe press for new worker protections to counter heat stress,” July 8, 2026; Euronews, “Heat stress threatens 130 million European workers, trade union body warns,” June 25, 2026; European Trade Union Institute (ETUI) heatwave worker protection report; CNV (Dutch trade union) worker heat exposure survey.