Many of us spend our summer days in air-conditioned offices or homes, where heat and wildfire smoke are nuisances but rarely life-threatening.

For outdoor workers, however, heat and smoke have become inescapable parts of summer shifts. When temperatures climb and air quality drops, roofs are still shingled, concrete is poured, garbage is collected, trees are trimmed, houses are painted, and fruits and vegetables are harvested by hand.

Combining physical exertion, time-sensitive work, and heat can have deadly results⁠—and agricultural workers are at particular risk. Heat-related illnesses and deaths are more prevalent among farmworkers than any other US occupation, including construction.

“Farmwork involves direct sun exposure and high workloads,” says Mayra Reiter, project director for occupational safety and health at Farmworker Justice, a Washington, DC–based nonprofit. “Many workers get paid on a piece-rate basis, which creates incentives to work harder, work faster, and work longer before taking breaks, and some employers discourage breaks.”

Across the West, climate change has made working outdoors riskier. In 2021, two Northwest agricultural workers died after working in triple-digit heat⁠—one at an Oregon blueberry farm and another in a hops field in Yakima County. By mid-century, the average number of days US agricultural workers spend laboring in unsafe heat conditions is projected to double.

That’s a challenging reality for Washington’s multibillion-dollar agricultural industry. And it’s an area where Washington State University researchers are working to provide information to industry leaders and policymakers, with a focus on practical solutions for protecting employees.

Mobile text alerts in English and Spanish will be available this summer, warning supervisors and outdoor workers when heat poses “moderate, high, or severe” risks. People can sign up for the free alerts through WSU’s AgWeatherNet service, which provides localized weather data and forecasts through a network of 368 WSU-operated and private stations across the state.

AgWeatherNet launched a Worker Heat Awareness portal and is working on the alerts with the Pacific Northwest Agricultural Safety and Health Center, which is run by the University of Washington, says Lav Khot, AgWeatherNet director and an associate professor of biological systems engineering.

Man stands in front of WSU weather monitoring tower
Lav Khot by weather monitoring equipment for WSU AgWeatherNet (Courtesy WSU College of Agricultural, Human, and Natural Resource Sciences)

Besides the warnings, the mobile alerts provide information about safety-related precautions to take on hot days.

“We’re getting the word out that this exists and it’s free to use,” Khot says. “The alerts will also be helpful for people in construction and other outdoor jobs.”

Other WSU health-related work focuses on understanding the combined threat that heat and smoke pose for the heart and lungs, and how socioeconomic factors heighten health risks for farmworkers.

“In the Northwest, we have the most farmworkers out in the fields during periods when they’re exposed to both heat and wildfire smoke,” says Julie Postma, associate dean for research at WSU College of Nursing. “After work, they’re not necessarily going to a place where they can recover. If you’re living in a trailer or low-income housing, you probably don’t have air-conditioning and air filters.”

Postma is part of the National Institute of Health’s 2024 Climate and Health Scholars cohort, which aims to increase climate change resiliency among individuals and communities.

Profile shot of Julie Postma
Julie Postma (Courtesy WSU College of Nursing)

About 160,000 people work in the agricultural and food industry in Washington, where industry officials have been active in discussions about worker health. Growers are used to contending with heat, says Jon DeVaney, president of the Washington State Tree Fruit Association.

“Heat has always been a consideration for growers⁠—for the safety of their workforce and for the quality of the fruit,” he says. “What is changing is that weather patterns have been less predictable. We’ve had some of these high heat days in June or early July when they aren’t as expected.”

Most of the state’s tree fruit crop is grown in semi-arid central Washington. Cherries are picked at the height of summer. Apple harvest starts in early August with Galas and Honeycrisps and extends through fall with later varieties.

Fruit harvest typically starts at daybreak to take advantage of the cooler parts of the day, but some growers have switched to nighttime harvest under artificial lights, DeVaney says. Scheduling night shifts helps reduce heat exposure for workers and damage to fruit, but many growers make night shifts optional, he says.

“Some workers really like it, but others find it too disruptive for their families,” DeVaney says. “Think about how hard it is to get childcare. It’s harder at night.”

Washington is among a handful of states that mandate temperature-related breaks, access to shade and cool drinking water, and heat awareness training for workers. The state’s smoke rule requires distribution of respirators when air quality crosses certain thresholds.

Washington rules also require close observation of employees during heat waves and when they aren’t used to physical activity at high temperatures.

Even healthy workers are at risk for heat-related illness or death, according to health officials. Heat generated by exertion⁠—combined with hot air temperatures⁠—can overwhelm the body’s ability to maintain a normal core temperature.

“Dehydration really matters in terms of tipping someone over the edge to heat stress or heat exhaustion,” Postma says. Being on medication can have the same effect.

Physical activity on hot days can damage the heart, lungs, and kidneys. And a rare but serious condition called rhabdomyolysis develops when damaged muscle tissue releases proteins and electrolytes into the bloodstream.

When workers acclimatize to heat by gradually ramping up their activity levels, they sweat more efficiently and more blood flows to the skin, enhancing cooling through evaporation. They also work at lower heart rates and with lower core body temperatures.

But acclimatization can take up to two weeks to develop, and it’s short-lived. Employees lose their acclimatization after a week away from working in a hot environment, Postma says.

Climate change will continue to increase the hazards of outdoor work. It’s a public health issue for agricultural communities, particularly where crops require high inputs of human labor, she says.

“I come at this as an advocate for workers’ health, but I feel for our growers,” Postma says. “They’re trying to abide by state regulations, keep their workforce healthy, and get their crops to market.”


Longer wildfire seasons…

…have also increased health risks for outdoor workers. The combination of extreme heat and air pollution is an emerging public health concern, with evidence of compounding impacts to heart and lungs and increased mortality rates.

For Julie Postma, the 2015 wildfire season was an eye-opener. More than a million acres burned across Washington that year, blanketing the skies with smoke from late June to September.

“The smoke was so pervasive; there was no getting away from it,” Postma says. “Heat and wildfire smoke were happening at the same time in a population with very little control over their workplace and few resources to deal with things.”

In 2021, Postma and WSU doctoral student Molly Parker interviewed a dozen agricultural employees in central Washington about their working conditions. Many reported staying on the job through heavy smoke that made them cough and their eyes burn. Some talked about long lines for drinking water and little access to shade. They worried that reporting unsafe conditions to supervisors would jeopardize their employment.

AgWeatherNet is working to get more localized air-quality information out to the public. A state grant helped pay for 21 sensors that track air pollution, including fine particulates from smoke and ozone levels. People can access that information through a free registration with AgWeatherNet.

In addition, a “Be Smoke Ready” campaign helps people protect their health on smoky days. AgWeatherNet developed and distributed the outreach materials in cooperation with the Pacific Northwest Agricultural Safety and Health Center and the Washington State Tree Fruit Association.