MOREHEAD, Ky. (AP) — Many farms, from vertical farming startups to traditional specialty crop growers, are marketing greenhouses as a way to shelter crops from climate extremes. But overlooked are the experiences of workers inside, who may swelter under high heat and humidity.

The number of greenhouse and nursery workers has increased by over 16,000 in recent years, according to the latest U.S. agricultural census, and there are still no federal heat rules to protect them.

The data, along with stories of current and former greenhouse workers, shows a growing population of people increasingly vulnerable to heat-related illnesses, injuries and death as global temperatures rise and greenhouses become more popular.

Here’s what to know from AP’s report.

Many farms, from vertical farming startups to traditional crop growers, are marketing greenhouses as a way to shelter crops from climate extremes. But that promise overlooks the experience of the workers inside, where many experience bad conditions (AP Video: Donavan Brutus)

Heat and humidity, a dangerous combination

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

Eulalia Mendoza said temperatures could spike between 105 and 115 degrees (41 to 46 C) in the summer inside the California greenhouse she worked in. She described being drenched in sweat and suffering from heat illness — headaches, nausea, ceasing to sweat.

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Other workers across the U.S. described losing weight, dizziness and fainting from extreme heat.

In those conditions, workers who don’t get enough breaks 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.

Little research or regulation, more workers

Between 2010 and 2019, nursery and greenhouse operations nearly doubled their hiring of H-2A agricultural visa holders. Without protections, their ability to speak up about working conditions becomes harder.

California recently approved heat rules for indoor workers, joining states like Oregon and Minnesota, but enforcing them can be tricky. For instance, workers are entitled to a 10 to 15-minute break, but that may be too short to shed and don their gear, so they may stay inside to ensure they’re back to work on time.

The Occupational Safety and Health Administration has two complaints about heat stress specifically in greenhouses, in 2005 and 2017. The low number of documented complaints may reflect workers’ concerns about retaliation if they report workplace conditions, said Abigail Kerfoot with Centro de los Derechos del Migrante, a migrants’ rights organization.

Few trainings for the vulnerable

Some current and former greenhouse workers said they didn’t get training to identify symptoms of or protect themselves from heat.

Emily Hernandez, who worked for a summer in a greenhouse in Orange County, said she never received heat safety training despite temperatures that could rise up to the high 80s.

“When I did bring it up, there was a company meeting about not complaining about the heat,” she said.

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.

On 100-degree days, researchers working in older greenhouses are encouraged to work early mornings, stay hydrated and take breaks in cooler areas.

Greenhouses as a climate solution

In what was supposed to be a “climate-resilient food system,” workers say temperatures frequently reached 113 degrees Fahrenheit (45 Celsius) inside facilities at the now-bankrupt AppHarvest, a startup with greenhouses in 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.

Indoor growing companies maintain that with the right management, greenhouse growing is a promising climate solution. To account for excessive heat, some say they adjust workers’ schedules, starting them earlier in the morning or later in the day when temperatures are cooler.

Aaron Fields, vice president of agriculture at greenhouse-based vertical farming company Eden Green, 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.

But Rebecca Young with the nonprofit Farmworker Justice said greenhouses can be healthy places to work, beginning with establishing worker protections. When temperatures are monitored; when workers get adequate breaks, water and training, then growing in greenhouses can be sustainable for humans and agriculture alike.

“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?” she said.

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