The “greenhouse effect”: How an oft-touted climate solution threatens agricultural workers

MOREHEAD, Ky. (AP) — To harvest tomatoes, peppers and cucumbers, to clip herbs, to prune and propagate succulents, people work in oppressive heat and humidity. Some wring out shirts soaked with sweat. Some contend with headaches, dizziness and nausea. Some collapse. Some hover on the brink of exhaustion, backs straining, breathing heavily.

Many do so not out in farm fields, but indoors – under the roofs of greenhouses. In structures designed to control the growing environment of plants, some workers described humidity with temperatures sometimes soaring past 100 degrees Fahrenheit (nearly 38 degrees Celsius).

“The heat is unbearable and the humidity equally so,” said Estela Martinez, speaking in Spanish of the six years she worked in a nursery in Florida. “I lost too much weight because my T-shirts were coming out soaked, soaked from the heat inside.”

The number of greenhouse and nursery workers has increased by over 16,000 people in recent years, according to data from the latest U.S. agricultural census. Some work in conventional operations like commercial nurseries, others in buzzy startups that tout indoor agriculture as a climate change solution.

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The data, along with stories of 10 current and former greenhouse workers approached by The Associated Press, shows a growing population of workers who are increasingly vulnerable to heat-related illnesses, injuries and death as global temperatures rise and greenhouses become more popular. They work in a gray area – they’re both indoor and agricultural workers, but are not always included in efforts to protect the latter.

But since it is possible to control greenhouse conditions, and many companies include greenhouses in their pitches for the promise of indoor agriculture, workers and researchers want protections and to have them enforced.

In those suffocating conditions, workers who don’t get enough time for breaks outside or in cooler environments, whose shifts are not pushed earlier or later in the summer and whose managers ignore their concerns are the most at risk.

“Many times we don’t leave to cool off (even) for a short while. It’s not because we wouldn’t want to do it, but because we’re scared that they would dismiss us,” Eulalia Mendoza said, speaking in Spanish. Mendoza worked in a greenhouse in Oxnard, California for the last three years of her 25-year career in agriculture.

“We don’t have an option,” she said. “That is the reality.”

Heat and humidity, a dangerous combination

During her time in the industry, Mendoza picked cucumbers in a greenhouse where the temperature could spike between 105 and 115 degrees (41 to 46 C) in the summer, she said. “You’d come out of there with your clothes drenched in sweat, as if you’d soaked your clothes in water,” she said. The exertion, coupled with the extreme heat and humidity, often lead to heat stress.

“Many of us didn’t know how to identify the symptoms of heat illness,” Mendoza said.

She recalled a hot day when she felt a headache and nausea before the greenhouse looked yellow. She had stopped sweating and was wheeled outside in a cart meant to carry overheated workers to fresh air. They pressed ice and cold cloths to her head, removed her shoes and the sweatshirt, hat and face cover she wore. When she recovered, they sent her home.

“That happens every day,” Mendoza said, adding that the first time she felt heat illness, about five other colleagues sat outside with similar symptoms. The second time, there were about a dozen.

Isabel Rosario Velasco, who works in a greenhouse in San Diego County, described similar symptoms. “When it’s really hot, your head can hurt and you feel dizzy ... sometimes it feels like you can’t breathe.”

A worker with the now-bankrupt vertical farming startup AppHarvest also recalled fainting from hot greenhouses. The worker, who spoke on the condition of anonymity for fear of retaliation, said “everything just started closing in on me.” He and others said temperatures frequently reached 113 degrees Fahrenheit (45 Celsius). “I stumbled and caught myself, but I had to be sat down and escorted out.” Within 20 minutes of entering the greenhouse, another colleague passed out, he said.

Heat combined with humidity makes it harder for sweat to evaporate to cool the body, creating a potentially more dangerous scenario.

While people can acclimatize to some of these conditions, the persistent misconception that certain racial groups can better tolerate heat is entirely untrue, said Bharat Jayram Venkat, professor and founding director of the UCLA Heat Lab.

If anything, Black people, Latinos and others from communities of color are more vulnerable to extreme heat because they’re more likely to be lower income, not have air conditioning at home, or live in hotter areas, he said.

Rebecca Young, director of programs at the nonprofit Farmworker Justice, has heard about farmworker housing that can lack shade, air conditioning and have poor ventilation.

Little research or regulation, more workers

Between 2010 and 2019, nursery and greenhouse operations nearly doubled their hiring of H-2A agricultural visa holders, according to the United States Department of Agriculture. But without some legally-binding protections, their ability to speak up about working conditions becomes harder.

There are no federal heat protections in the U.S. for agricultural workers, nor are there federal guidelines specifically requiring greenhouses to measure temperatures and humidity, though the Biden administration recently proposed a rule for workplaces to address heat.

California’s branch of the Occupational Safety and Health Administration recently approved regulations for indoor heat, and several other states have their own rules on heat illness prevention. But enforcement of them can be tricky: for instance, workers are entitled to a 10 to 15-minute break, but that may be too short for them to properly shed and don their gear and so they may stay inside to ensure they’re back to work on time.

When Mendoza worked in a greenhouse, it would take about 10 minutes to walk from her work station to a shaded area for a break, then another two to three minutes to shed her work clothes and plastic covers on her shoes. By then, her break was over. “So what we would normally do is not go outside,” she said. “Sometimes we would take our breaks inside the greenhouse... and only go outside for lunch.”

OSHA only has in their database two formal complaints about heat stress specifically in greenhouses, one in 2005 and one in 2017. That may reflect workers’ concerns about retaliation if they report life-threatening workplace conditions, said Abigail Kerfoot, senior staff attorney at Centro de los Derechos del Migrante, a migrants’ rights organization. She pointed to what she calls “structural issues” with temporary visas and subcontracting of migrant labor in the United States.

Kerfoot said she has seen attempts by greenhouse employers to “distance” themselves “from responsibility for its workers through the use of subcontracting arrangements,” which essentially means they’re not directly responsible for their workers.

Between 2012 and 2022, 418 people died from work-related exposure to heat across industries, according to data from the U.S. Bureau of Labor Statistics.

There is little research documenting the working conditions of greenhouse workers. Many of the studies that do exist are in countries outside of the U.S.

Few trainings for the most vulnerable

It was the summer of 2020 in Orange County, California when Emily Hernandez started her first job in a greenhouse. She recalled the humidity and “intense heat” she experienced 40 hours a week as she tried to swiftly weed and re-pot the “hundreds upon hundreds” of succulents she was tasked with.

The pressure to work fast gave her anxiety, and her back often strained from bending over. But the heat, she said, was the worst part.

Hernandez said in the five weeks she worked there, she never received heat safety training despite temperatures that could rise up to the high 80s. “It was kind of learning as you go,” Hernandez said.

Instead, safety and comfort tips came from colleagues: Bring a fan. And a chair. Keep one water bottle in the freezer and one with you always.

“There was really no concern for safety in that way,” Hernandez said. “When I did bring it up, there was a company meeting about not complaining about the heat.”

Universities with greenhouses do things differently. At the University of California, Davis, students, staff and researchers are required to take greenhouse safety trainings that cover heat illness protection, injury reduction, emergency guidance and the federal worker protection standard.

Most of the campus’ greenhouses automatically cool or heat the environment at certain temperatures, according to Bill Werner, lead greenhouse manager for UC Davis’ College of Agricultural and Environmental Sciences. On 100-degree days, researchers working in older greenhouses are encouraged to work early mornings, stay hydrated and take breaks in cooler areas. Various complexes also have shade and stations with cold potable water.

While research and commercial greenhouses share similar goals of creating optimal growing environments for plants, a major difference is the amount of time people spend in them.

Like Hernandez, agricultural workers often labor eight hours or more a day, five or more days a week inside commercial greenhouses. At UC Davis, people spend an average of 15 minutes to an hour daily inside greenhouses, said Werner, but can be in there for hours if they’re collecting data or setting up a project.

“I don’t think I’ve ever seen anybody here just eight hours straight,” he said.

Can greenhouses still be a climate solution?

In what was supposed to be a “climate-resilient food system,” workers say temperatures frequently reached 113 degrees Fahrenheit (45 Celsius). That was inside facilities at AppHarvest, an ambitious startup backed by Martha Stewart with multiple massive tomato greenhouses in rural Kentucky that touted itself as a climate solution.

Workers say they saw colleagues carried out on makeshift stretchers, and dozens more helped outside on others’ shoulders.

“I started getting really sick from the heat. And my body started shutting down on me,” said one worker, speaking on condition of anonymity for fear of retaliation. “And when I passed out and went home that day, I’d just laid there, and I was thinking, like, ‘I can’t keep doing this.’”

It wasn’t just summer heat causing these conditions: several AppHarvest workers said the company was riddled with mismanagement. They said there were a couple iterations of a worker orientation, but that it was “boring and breezy” and didn’t adequately cover greenhouse safety. Some said they sometimes couldn’t keep water bottles in the greenhouse because they might knock against the plants and damage the fruit, or because it looked bad when visitors came through on tours.

One anonymous contract worker formerly with AppHarvest, speaking in Spanish, said the company’s greenhouses were “plagued by rats.”

AppHarvest, which has since declared bankruptcy, did not respond to a detailed list of questions about these problems, though their 2021 sustainability report featured a section devoted to employee wages, benefits, career paths and safety. “Nothing can be grown without the people that we have,” the report stated, quoting the senior manager of environmental health and safety at the time. “We must protect our greatest asset, which is people.”

Other indoor growing companies maintain that with the right management, greenhouse growing is a promising climate solution.

“You’ve got climate change that is just exacerbating issues for outdoor growers,” said Steve Bradley, president of Cox Farms, a greenhouse-based indoor growing company. He says that with greenhouses sheltering crops from extreme heat, his company has “decoupled the growing from these external weather patterns.”

Bradley said that his modernized greenhouses have the technology to be completely climate controlled.

Day temperatures in their current greenhouses range from 70 to 85 degrees Fahrenheit (about 21 to 29.5 Celsius), and humidity levels average about 80%, according to the company. Summer brings temperatures between 82 to 85 degrees Fahrenheit (about 28 to 29.5 Celsius), but when equipment fails, it can soar to 95 degrees. To account for excessive heat, they adjust workers’ schedules, starting them earlier in the morning, breaking mid-day during peak heat, and returning in the evening as temperatures cool, the company said.

Aaron Fields, vice president of agriculture at greenhouse-based vertical farming company Eden Green in Texas, said that temperatures in their greenhouses regularly hover between 70 and 80 degrees Fahrenheit (21 to 27 Celsius) but can get hotter during the summer, sometimes above 90 (32 degrees Celsius). A few years ago, they shifted their workers’ summer schedules to earlier in the day so they aren’t working inside at the hottest hours.

Fields added that it’s important to be trained to identify symptoms of heat stress, to work in a buddy system and to stay hydrated.

He thinks the startup culture of “high-tech” greenhouses, which can include leaders and founders without prior farming experience, has led some to miss the importance of working conditions. “Unfortunately, some of these were safety protections or the things that go unnoticed … those became the last priorities,” he said.

It’s all about establishing rules to protect workers, explained Young from Farmworker Justice. When temperatures are monitored; when workers get adequate breaks, water and training; when they aren’t trapped inside with pesticide residues too soon after application, then growing in greenhouses can be considered sustainable for humans and agriculture alike.

“A greenhouse can be a very healthy place to work,” Young said. “It’s sort of thinking about, how can we interact with the climate around us in a way that keeps people and the food that we’re eating healthy and safe?”

While technology and good practices exist to ensure workers are safe and comfortable in greenhouses, many can’t chose the environments they spend much of their days in.

“We don’t have the option to pick our work,” Mendoza said. “We have to accept what there is.”

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Pineda reported from Los Angeles.

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