Workers trim leaves on Pinot Noir vines in Petaluma, Calif., in May. (Eric Risberg/AP)

David Arkush is the managing director of the Climate Program at Public Citizen. David Michaels, a professor at George Washington University, served as administrator of OSHA from 2009 to 2017.

We are smashing heat records again this summer. We hear this so much now that there’s a risk we will start ignoring it before the key message sinks in: Global warming is here, and it’s starting to cook us.

Not just the planet — us. Heat is the leading weather-related killer in the United States, and the toll (estimates range up to 1,300 deaths per year) will rise steeply in the coming decades. Even if we halt climate change as quickly as possible — as we certainly should, to avoid beyond-catastrophic harms — the heat will still get a lot more uncomfortable, and a lot deadlier, before it levels off.

At present we have no federal rules to protect workers from heat; that needs to change. At one point, we came to different conclusions on this issue. One of us manages a program at Public Citizen, a consumer rights advocacy group that petitioned the Occupational Safety and Health Administration for such a standard in 2011 . The other denied that petition as administrator of OSHA because agency resources were stretched thin by multiple other rulemakings. But today, we agree — along with more than 130 labor, public health and environmental justice groups that are petitioning OSHA once again — that it’s time for the agency to write long-overdue heat stress protections.

Outdoor workers are particularly vulnerable. Many have little protection from the heat, and compared with the general population, they have less leeway to rest, drink water or seek shade or air conditioning. Many indoor workers are affected too, for example, in warehouses or steel plants, not just because they labor in oppressively hot conditions but also because extreme outdoor heat limits their ability to cool down in the off hours, leaving them more vulnerable on the job.

It is notoriously difficult to track workplace heat illnesses and fatalities. The symptoms mimic those of other common conditions, and heat can be an unrecognized contributor to heart attacks, strokes and other health events. Some of the highest-risk workers, including non-English speaking, undocumented and migrant laborers, are the least likely to report symptoms, for fear of lost work time or retaliation. But what evidence exists, combined with statistical inferences and common sense, suggests that heat stress is a silent epidemic, possibly one of the leading workplace dangers in America. And climate change is making it deadlier.

We know what rules to protect against heat should say, and they are not complicated. In fact, we already have a real-world example of simple, extremely effective heat-protection rules: OSHA’s guidelines for workers cleaning up the 2010 BP oil spill.

In April 2010, the Deepwater Horizon rig exploded, and oil began hemorrhaging into the ocean. That summer, more than 40,000 workers wearing chemical-resistant suits, hard hats, and impermeable gloves and boots cleaned up oil in the shadeless heat of the Gulf Coast states of Louisiana, Mississippi, Texas, Alabama and Florida. The cleanup teams included many who were overweight and had preexisting lung and heart problems, which can increase the risk of heat illness.

OSHA insisted that BP and its contractors follow the work/rest regime that the military used to protect U.S. soldiers from heat stress in Iraq. BP accepted these rules voluntarily, probably eager to avoid more deaths beyond the 11 workers killed by the explosion. Some cleanup workers labored for 40 minutes on, 20 minutes off. In the most extreme heat, some rested more than they worked and hydrated in the shade while resting.

This strategy didn’t make the news because it was so successful — not a single worker was killed by heat.

We need to protect workers from extreme heat before it grows more intense, and we know how to do it. If business owners shudder at the prospect of letting outdoor workers rest for half their time or more on the hottest days, then they should imagine what will happen to workers and the economy if we permit today’s most extreme temperatures — and worse — to become commonplace.

That’s where we are headed on our current greenhouse-gas pollution path. And as climate impacts go, losing summer outdoor labor in whole regions of the United States is the small stuff. We need to get ahead of this problem before we face devastating consequences for public health and the economy.