Study Finds Extreme Heat Could Threaten $55.4 Billion Annually in Outdoor Worker Earnings by Midcentury

Between now and 2065, climate change is projected to quadruple U.S. outdoor workers’ exposure to hazardous heat conditions, jeopardizing their health and placing up to $55.4 billion of their earnings at risk annually if no action is taken to reduce global warming emissions, according to a new report released today by the Union of Concerned Scientists (UCS). This research is currently being reviewed for journal publication and is available on a preprint server.

“Outdoor workers—including those in agriculture, construction, delivery services and emergency response—are essential to keeping the fabric of our society intact,” said Dr. Rachel Licker, report author and a senior climate scientist at UCS. “The last seven years have been the hottest on record. Without additional protections, the risks to workers will only grow in the decades ahead as climate change worsens, leaving the roughly 32 million outdoor workers in our country to face a brutal choice: their health or their jobs.”

The “Too Hot to Work” analysis found that nationally by midcentury, assuming no reduction in global warming emissions:

• For approximately 18.4 million outdoor workers in the United States, extreme heat would put an average of seven or more workdays at risk annually; roughly 3 million workers have experienced this level of risk historically.
• Total outdoor worker earnings at risk due to extreme heat are projected to reach about $55.4 billion annually.  
• Outdoor workers in construction and extraction occupations are projected to face the highest total earnings at risk due to extreme heat at about $14.4 billion annually, followed by those in installation, maintenance and repair occupations at about $10.8 billion annually.
• The average outdoor worker risks losing more than $1,700 in annual earnings due to extreme heat, though workers in the 10 hardest-hit counties risk losing nearly $7,000 per year on average.
• The average outdoor worker in installation, maintenance, repair and protective service occupations stands to lose the most annual income at approximately $2,200 due to extreme heat.

The “Too Hot to Work” report combines county-level projections of dangerously hot days in the contiguous United States from the 2019 peer-reviewed UCS analysis “Killer Heat in the United States” with U.S. Census data on workers in the seven occupational categories with the highest proportion of outdoor jobs and U.S. Centers for Disease Control and Prevention (CDC) recommendations for keeping outdoor workers safe during extreme heat conditions. The number of workdays at risk is calculated by adding the partial days lost when the combined heat and humidity reach between 100 and 108 degrees Fahrenheit—a range in which the CDC recommends employers reduce work schedules—and entire days lost when such conditions exceed 108 degrees Fahrenheit, the threshold at which the CDC recommends employers stop work. The report does not project future changes in the number or distribution of outdoor workers. Midcentury results are determined by averaging the findings for the period between 2036 and 2065.

People of color have been and will continue to be hit especially hard by extreme heat for a number of reasons, including that they are disproportionately represented in many outdoor occupations. More than 40 percent of U.S. outdoor workers identify as African American, Black, Hispanic or Latino, despite these groups comprising about 32 percent of the general population. Outdoor workers who identify as African American, Black, Hispanic or Latino risk losing an estimated $23.5 billion in annual earnings by midcentury if no action is taken to reduce global heat-trapping emissions.

“When combined with existing inequities resulting from centuries of systemic racism—such as increased exposure to air pollution, lack of access to quality health care and adequate cooling, and underfunded social services—extreme heat will exacerbate the risks outdoor workers of color already face,” said Dr. Kristina Dahl, report author and a senior climate scientist at UCS. “Migrant and undocumented workers may be further constrained in their ability to seek safety protections from dangerous heat due to the threat of employer retaliation, which could even result in deportation.”

For farmworkers, who die of heat-related causes at roughly 20 times the rate of workers in all other civilian occupations according to CDC data, the danger of extreme heat is compounded by routine pesticide exposure.

“It’s a deadly cycle. Heat stress makes farmworkers more susceptible to injury from toxic pesticides, while the heavy protective clothing they must wear increases the risk of heat-related illness,” said Dr. Marcia DeLonge, a research director and senior climate scientist in the Food and Environment Program at UCS and an author of the 2018 “Farmworkers at Risk” report. “Moreover, climate change is amplifying the risks by causing an increase in insect pest populations and making weeds more abundant, which will likely drive more pesticide use, further endangering the people who put food on our tables.”

The report offers state- and county-level data too. By midcentury, assuming no reductions in global heat-trapping emissions: 

• The states with the highest total outdoor worker earnings at risk annually due to extreme heat are Texas ($12.2 billion), Florida ($8.4 billion), California ($3.3 billion), Arizona ($2.6 billion) and Louisiana ($2.3 billion).
• The states where the risk of lost annual income due to extreme heat is greatest for the average outdoor worker are Louisiana ($4,700), Florida ($3,700), Oklahoma and Texas ($3,500), and Mississippi ($3,400).
• The states where outdoor workers would have the highest number of workdays at risk on average annually due to extreme heat are Louisiana (34 days), Florida (33 days), Mississippi (28 days), Arkansas and Oklahoma (27 days).
• There are nearly 2,000 counties nationwide where outdoor workers comprise 25 percent or more of the workforce. Roughly 1,200 of those counties would experience 30 or more days per year when the heat index exceeds 100 degrees Fahrenheit, up from about 130 counties historically.

About 20 percent of the U.S. labor force works outdoors, with significant numbers of outdoor workers located in urban areas and outdoor workers comprising a larger share of the local economy in rural communities. These workers are largely unprotected as federal guidelines are only recommendations. In addition to the CDC guidelines, the U.S. Occupational Safety and Health Administration (OSHA) merely suggests that employers implement safety precautions when the heat index, or “feels like” temperature, exceeds 90 degrees Fahrenheit.

“While there are suggested guidelines, the United States doesn’t have enforceable national heat-safety standards to protect outdoor workers during extreme heat,” said Dr. Dahl. “Furthermore, only two states—California and Washington—have any such permanent standards. The lack of safeguards during extremely hot days has historically left workers exceedingly vulnerable to heat-related illnesses and even death.”

UCS experts found that workers could stay safe and continue to work most days if their schedules were adjusted to coincide with cooler hours and their workloads were reduced to light levels. Coupling these strategies would ensure most workers would lose fewer than seven days of work per year on average by midcentury. Report authors caution, though, that there are practical limits to how much workloads and schedules can be adapted, so reducing global warming emissions remains essential for limiting the number of extreme heat days workers will experience.  

“To limit future extreme heat, the United States must urgently contribute to global efforts to effectively constrain heat-trapping emissions by investing in just and equitable solutions that get us to net-zero emissions no later than 2050,” said Dr. Licker. “Our analysis also recommends that all levels of government take action now to better protect our nation’s essential outdoor workers. We know this risk is worsening and has significant implications for workers, employers and the broader economy, so we need to be prepared.”

The report urges Congress to adopt the “Asunción Valdivia Heat Illness and Fatality Prevention Act of 2021,” legislation named in remembrance of a California farmworker who died from preventable heat stroke after picking grapes for 10 hours straight in triple-digit temperatures. The bill would direct OSHA to set protective standards—such as mandating that employers provide adequate hydration, shade and rest breaks—for outdoor workers regularly exposed to heat.

Other worker safety recommendations include requiring employers to create science-informed heat safety plans that would be enforced by OSHA; implementing heat safety monitoring and reporting requirements; providing multilingual training to supervisors and workers so they can better recognize and respond to the dangers of extreme heat; and ensuring workers have access to fair wages, affordable health care, cool housing, and legal protections.

To view the report PDF, click here.

Spreadsheets with data are available by state and by county. National data results can be found here.

To use the interactive mapping tool, click here. The map, which becomes more detailed when you zoom in, allows you to learn more about outdoor workers’ exposure to extreme heat and the corresponding economic implications by county.

For all other materials, including state-specific press releases, corresponding blogs, a related “Got Science” podcast episode, and Spanish-language materials, click here.