by From the other side of the world, the uncomfortable conditions of Shamim Ahamed and Purvi Tiwari doing Ph.D. research inside greenhouses inspired them to study the heat in the inner structures.
Tiwari, a researcher at India’s Indira Gandhi Agricultural University, realized the heat-amplifying effect of greenhouses was a big concern because she herself had experienced the leg cramps, sadness and dizziness her farmers described more recently. Outdoor summer temperatures can reach 120 degrees Fahrenheit (50 degrees Celsius) in parts of India, where greenhouse workers “feel suffocated inside.” She also said that in the last five years, greenhouses have become a trend and the available land is decreasing in the midst of development.
“Workplaces shouldn’t harm people,” she said. “If that work area is harming that person, that means it’s not good to work. That should change.”
In the United States, the latest agricultural census shows that the number of greenhouse and nursery workers in the United States has increased by 16,000 in recent years. But there are no federal heating rules even as greenhouses have become more popular and the number of workers in them has increased. There is also little research into the experiences of workers and their wider working conditions, or how to protect people who work within their often hot and humid environments. But academics from around the world, like Tiwari and Ahamed, are trying to fill the knowledge gaps about the unique conditions greenhouse farm workers are exposed to.
Bharat Jayram Venkat, associate professor and founding director of UCLA’s Heat Lab, said “there’s a lot of research going on in agricultural workers…but not specifically looking at greenhouses.” Most of the literature focuses on maximizing plant growth and production in greenhouses. not on human health.
“In that sense it makes sense — that’s why greenhouses exist. But of course you need human workers in those greenhouses to make them function,” he said, “so you have to think about human health.”
More heat, more greenhouse workers
Last year was the hottest on record and cities across the US experienced triple digit temperatures several times. According to the United States Department of Agriculture, the number of farms and square feet under glass, and the value of greenhouse and nursery sales, have all increased since 2017. In addition, the use of the H-2A agricultural worker program has essentially doubled over the period from 2010-2019, with implications for the ability of workers to complain about extreme heat conditions.
Venkat expects more research to emerge as indoor, climate-controlled growing environments are likely to become more popular as climate conditions become less predictable and more extreme. Laws like California’s recently approved indoor heating rules and the rise in greenhouse workers will also increase interest in studying them, he said.
Jennifer Vanos, associate professor at Arizona State University, has researched the limits of survival and physical work capacity in extreme heat. Using research led by a former fellow at Loughborough University – which assessed how the body functions under different temperatures, wind speeds, humidity and radiation – Vanos and his colleagues studied the productivity of agricultural workers in a warming planet.
Among the findings was that the warmer it gets, the less productive workers may be, which has economic implications. In the context of agriculture, this may mean that fewer crops are harvested and more workers are needed.
Ultimately, their findings found that “in order for people to work safely, they need to lower their heart rate, which means lowering their exercise output to be able to perform the same tasks in an environment warmer,” Vanos said.
Symptoms of heat stress include heavy sweating, cramps and a fast heart rate. Extreme temperatures can increase the risk of injuries due to dizziness, weakness or fainting. And heat stroke, the most serious heat-related illness, can occur when the body stops sweating and its temperature rises.
When the heat combines with humidity, it is harder for the sweat to evaporate to cool the body, creating a potentially more dangerous situation.
“When the air is already really saturated with water vapor… the ability to evaporate sweat is greatly reduced,” Venkat said. “That means your risk of heat-related illness or even death will be much higher.”
Filling research gaps
Researchers Tiwari and Ahamed have now published papers on greenhouse environments. Ahamed, now an assistant professor in the Department of Biological and Agricultural Engineering at UC Davis, studied the risks of heat exposure in high-tech greenhouses, comparing the effects on workers when using tools such as “skins” shaded in greenhouses to keep temperatures cooler. . Tiwari spoke to workers in India who experienced nausea, drowsiness and dehydration, and she and her team found that greenhouse workers working in the middle of the day had an average heart rate 20% higher than those in open fields .
Ahamed said Tiwari’s research is relatively rare. Many of the studies that exist are in countries outside the US And even when studies are based in the US, it can be difficult to get a proper sample of greenhouse workers in particular.
For example, researchers at UC Merced found higher rates of preterm birth, low birth weight and birth defects in pregnant agricultural workers across the board – including field and nursery workers. A study from Iran found similar effects in greenhouse workers there, but the UC Merced team said they didn’t have enough pregnant indoor agricultural workers to look with confidence at that result alone.
Because of the holes in the literature, Ahamed said, there is “a huge gap in how these things could be regulated or standardized.” He thinks building codes need to be based on UV, heat and moisture exposure as well as safety procedures for indoor workers.
But with such a wide range of greenhouse technology in use – from mega-farms on many acres to micro-climates created with “high tunnel” or “hoop house” setups in which plastic is arched over small sections of a field – there is always a variety of possible options. issue towards implementation standards.
However, he thinks it would be possible to have different protocols in place depending on the type of greenhouse at hand.
“For this, they need to investigate, to find some recommendations,” said Ahamed.
___
The Associated Press’ climate and environmental coverage is financially supported by multiple private foundations. AP is responsible for each and every subject. Find AP standards for working with philanthropies, a list of supporters and covered areas of funding at AP.org.
