Heat is a mortal threat to farmworkers. A nurse may have found a way to protect them.

The fern sprays grow to waist height, and to harvest them, workers must stoop, hunching their way through fields covered in black tarps. The tarps shield the ferns from the weather, but they do the opposite for the workers, trapping and amplifying the Floridian heat, which can easily rise past 100 degrees Fahrenheit.

In the past, Severa would push herself to work faster, through sweat and thirst to exhaustion, even a feeling of suffocation, because the heat exacerbates her asthma. She knew working so hard in the heat made her feel ill, but if she wasn’t cutting, she wasn’t earning money. Fern cutters are generally paid by the bunch, not by the hour — Cruz gets 45 cents per bunch, 20 fern sprays to a bunch.

Then she enrolled as a participant in community-led research at the Farmworker Association of Florida carried out by Roxana Chicas, a nurse-researcher from Emory University investigating the effects of hot weather on farmworkers’ health. There, Severa learned that those signals from her body — the headaches, the wheezing — are not just discomfort. They could be precursors to severe problems including organ injury and even death by heat stroke. When your body sends you those signals, she recalls Chicas telling them, you have to take a break, find shade, drink water, even if your boss doesn’t make it easy. Nothing is worth your life.

Now, Severa listens to her body — even if it means taking less money home.

Chicas’s research has many aims, but arming farmworkers with information to better protect themselves is one of the most important.

As the climate becomes warmer and more humid, people who work outdoors are some of the first to contend with life-threatening heat exposure. Outdoor workers are like canaries in the climate coal mine, researchers say. Measuring and mitigating how heat affects them is critical, not only because they have a right to safety and the U.S. food supply depends on their health, the researchers say, but because the world also needs to prepare for these impacts to worsen and affect more people.

Climate canaries

Already, agricultural workers are at least 35 times more likely to die of heat than other workers, according to the National Institutes of Health. Florida, like the vast majority of states, does not require employers to do anything to protect farmworkers from the heat. The Occupational Safety and Health Administration (OSHA) recommends that employers modify work during hot weather and provide water, rest and shade, but no federal regulations require these accommodations, and many employers do not provide them. Only California, Oregon, Colorado and Washington have mandated heat protections for outdoor farmworkers.

Texas recently took a step in the opposite direction, after Gov. Greg Abbott signed a law that will prevent local officials from establishing their own heat protections for workers. This means, for instance, that Austin and Dallas, which had mandated water breaks for construction workers, will no longer be able to do so.

So far, the industry has pushed back against regulations, citing cost. Floral Greens Farmers of Florida Cooperative, a group of 40 fern growers, declined to comment on heat-related protections for workers, and several individual growers contacted by The Washington Post did not respond to requests for comment. But, pressured by mounting evidence of a crisis, OSHA is exploring the possibility of federally mandated heat protections for workers, but the agency has not publicly set a schedule for establishing regulations, a process that usually takes years.

In the meantime, what the Cruz sisters learned by participating in Chicas’s research has allowed them take matters into their own hands to a degree. They now know how to recognize the symptoms of heat-related illness and what to do when they detect them.

For Chicas, whose research is a collaboration with community organizers at the Farmworker Association of Florida, this work is personal. She was born in El Salvador, where her mother grew corn, beans and coffee. When the Salvadoran civil war broke out in 1979, children were often kidnapped and never seen again. In 1986, when Chicas was 4 years old, she and her mother fled that terror to the United States. They settled in Georgia, where Chicas’s mother worked as a housekeeper and often told her daughter that she was grateful to have an indoor job that protected her from the weather.

Back then, Chicas’s mother may have intuited what scientists were about to find out: In the 1990s, large numbers of agricultural workers in El Salvador started going to hospitals with end-stage kidney failure, but they did not have any of the typical risk factors for renal disease. They were relatively young people who worked outside, often on sugar cane plantations. The kidney failure, dubbed chronic kidney disease of unknown etiology — meaning the cause was a mystery — was found throughout Central America.

Scientists eventually realized the disease was showing up in farmworkers in other hot, humid parts of the globe, including Sri Lanka, India, Egypt and Sudan. It is now a leading cause of death in El Salvador. This kidney failure occurs in the United States, too, although it is hard to say to what extent, because the health system is fragmented, and the immigrant farmworker community often cannot obtain regular health care.

The exact cause of this kidney failure remains a mystery, although there is a hypothesis: It is closely associated with hard outdoor labor in extreme heat and humidity. Farmworkers suffer repeated heat-related illness, which is defined by a body temperature over 100.4 degrees. This can damage organs, including the kidneys.

Many people are familiar with heat stroke — a body temperature of at least 104 degrees, which can kill quickly, but this lower-level heat-related illness combined with dehydration is associated with kidney injury and also can be life-threatening, if more slowly. Scientists do not know why some farmworkers are affected and others are not. But the data suggests that many farmworkers have crossed a dangerous climate-change threshold.

Field work

Now 40 years old, Chicas is a nurse PhD conducting postdoctoral research in nephrology and also an investigator. She and her colleagues, including principal investigator Linda McCauley, the dean of Emory’s Nell Hodgson Woodruff School of Nursing, are studying the effects of heat on farmworkers.

McCauley, who was trained as a maternal-child health nurse, said the research took off after she turned her attention to heat hazards for pregnant farmworkers. “No one had really talked to these farmworkers about heat exposure,” McCauley said. “The women gave us wonderful data about the symptoms that they had from working in the heat. But they also said, ‘This is so important to us, and you shouldn’t just study women. Our husbands, our sons are experiencing this too.’”

One of their studies, published in 2018, collected blood and urine samples from 192 farmworkers over 555 workdays during the summers of 2015 and 2016 to measure hydration and kidney function. They found that, on any given day that the workers were tested, 33 percent of them had incurred kidney injury and that the likelihood of injury increased with the heat index.

In an as-yet unpublished study, Chicas and McCauley looked at the progression of 119 workers’ kidney function over 32 months and found it declined precipitously over that time for per-piece workers, who like Cruz, often work even harder than workers who are paid by the hour. Initially, 10 percent of the piece workers were suffering kidney injury on any given workday. More than two years later, that share had jumped to 43 percent. Their kidneys’ ability to filter waste also declined steeply. The effect was so dramatic that the team went back and re-collected data to make sure the findings were correct.

Chicas asks community members what questions they have and what they need, and she designs research accordingly. This kind of work, in which communities have a say over the questions asked and the data gathered — instead of being “subjects” — is often called community-based participatory research, and researchers say these coalition-led interventions can result in data that is more meaningful.

For example, Chicas started incorporating mini-physicals into her data collection because the workers told her they needed to know their general health status — blood pressure, blood sugar, cholesterol — but did not have health insurance or time off. She does blood and urine analyses and lets participants know whether they have diabetes or hypertension, gives them referrals, helps with their medications and recommends everyday life changes that could help. She also talks to them about the symptoms of heat-related illness, how to identify it in themselves or co-workers and what to do.

“It’s pivotal, groundbreaking work,” said Lee S. Newman, who directs the Center for Health, Work and Environment at the Colorado School of Public Health and is not involved in Chicas’s research. “In the U.S., there is very little work like Roxana and that team are doing.”

“We need people who are going out there and trying things and measuring whether they’re actually reducing the way that heat is affecting the health of these workers,” he added.

Chicas is uniquely situated to understand this crisis. She sees herself in the people with whom she works. “We’re immigrants. I was undocumented until I was 18. I understand how it feels, having to lay low and not rock the boat,” she said. “I want to give back to a population that is very much invisible to the general public, yet everyday, we are all touched by their work: We all have to eat.”

Easing the heat

Everyone agrees that there is no substitute for regulations. “The regulatory piece is critical. We have failed to date to get a federal standard to protect farmworkers from heat. And that is unconscionable, particularly given the increasing number of high-heat days,” said Amy K. Liebman, who directs worker health and safety programs at the Migrant Clinicians Network, a nonprofit health organization. “We want to make sure that we’re not putting the onus of responsibility for worker protection onto the worker.”

In the meantime, though, giving workers tools will mitigate the harm — perhaps even save lives — and potentially empower workers to advocate for better working conditions. The best chance of creating effective tools lies in understanding the people who are going to use them, McCauley said. “We need more researchers like Roxana. We need people who can keep a foot in both the community and the science.”

Chicas tested the effectiveness of electrolytes. She found none of the workers who drank such liquids sustained kidney injury, whereas there was kidney injury in 23 percent of the control group, whose members drank plain water.

She also ran a small pilot study that tested the effectiveness of a reusable, inexpensive cooling bandanna that absorbs water that then slowly evaporates, creating a cooling effect much like sweating. The workers wearing the bandanna were less likely than a control group to experience an increase in core body temperature to 100.4 degrees or higher, and if their body temperature did rise to 100.4, the bandanna group spent less time — a median of three minutes — at or above that temperature than the control group did.

Severa said she liked using the cooling bandanna she was given as a study participant but didn’t replace it when it got old. She now uses a regular wet bandanna around her head or neck, which she says keeps her cool, but its effectiveness is not backed by the evidence.

This illustrates an inherent complexity: Research can identify effective tools, but those tools also must fit into the workers’ lives. This is complicated by the fact that many are undocumented and low-income.

Still, participating in Chicas’s research has changed Severa Cruz’s understanding of her work and her body. Before, she would push herself to take no breaks at all over her five-hour workday and pick about 250 bunches for ferns for about $112 per day. Now, when it’s hot, she makes sure she takes at least two 10-minute breaks in which she drinks plenty of water. It means that sometimes she picks only 200 bunches and takes home about $90 a day.

“The research helped alert workers to these risks and that idea that you need to rest when your body is giving you the signal to do so,” she said through a translator.