Extreme heat from climate change puts 32 million U.S. workers at risk of lost wages and illness

Outdoor laborers could lose $55.4 billion annually

A construction worker in Los Angeles.

Agence France-Presse/Getty Images

A new report suggests that rising temperatures and the greater likelihood of extreme heat caused by climate change will put the 20% of the U.S. labor force that works outside at risk for occupational illnesses and billions in lost wages annually if no action is taken to reduce global-warming emissions.

In a study released Tuesday, the Union of Concerned Scientists say 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.

That’s 32 million people who work outdoors in industries as diverse as agriculture, construction, delivery services and emergency-response jobs.

Exposure to extreme heat may result in a range of occupational illness and injuries, including some that are fatal, says Dr. Kristina Dahl, who co-authored the report, “Too Hot to Work,” with Dr. Rachel Licker, both senior climate scientists at the Union of Concerned Scientists.

Minor illnesses include headaches, fatigue, confusion and dizziness, while more serious illness are heat exhaustion and heat stroke; the later can be fatal, she says. “Extreme heat can also exacerbate existing underlying conditions like cardiovascular disease and diabetes,” she says.

Workers in the 10 hardest-hit counties risk losing nearly $7,000 per year on average.

Last week the Intergovernmental Panel on Climate Change issued its sixth assessment report on climate change, saying that global warming is happening faster than expected, and for 1.5°C of global warming, there will be increasing heat waves, longer warm seasons and shorter cold seasons.

The report combines county-level projections of dangerously hot days in the contiguous U.S. It builds on a 2019 peer-reviewed UCS analysis “Killer Heat in the United States.” The new report is currently being reviewed for journal publication.

Assuming no reduction in global warming emissions the report “Too Hot to Work” analysis found:

  • For approximately 18.4 million outdoor U.S. workers, extreme heat would put an average of seven or more workdays at risk annually. Historically, roughly 3 million workers experienced this level of risk.
  • Earnings by outdoor workers in construction and extraction occupations are at the highest total 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.
Most at risk
Counties in the contiguous U.S.; estimates assume a normal schedule and moderate workload, no action of climate risk 
County State Total earnings at risk at midcentury, in millions*
Harris County Texas $2,456.93
Maricopa County Arizona $1,958.85
Miami-Dade County Florida $1,432.25
Dallas County Texas $1,127.38
Broward County Florida $997.58
Tarrant County Texas $904.78
Riverside County California $919.64
Bexar County Texas $685.47
Palm Beach County Florida $613.94
Hillsborough County Florida $594.62
*Midcentury is defined as 2036-2065

Licker and Dahl calculated the number of work days at risk by adding the partial days lost when the combined heat and humidity reach between 100 and 108 degrees Fahrenheit, a temperature range the CDC recommends employers reduce work schedules. When temperatures exceed 108F, the CDC recommends all outdoor work stops.

U.S. Occupational Safety and Health Administration suggests employers use safety precautions when the heat index, or “feels like” temperature, exceeds 90 degrees.

Workers whose earnings and health are most at risk annually from extreme heat reside Texas, Florida, California, Arizona and Louisiana, although workers in states as far north as southern Iowa and central Illinois are also on the list. The report has an interactive mapping tool with a breakdown state-and-county-level data.

Health effects and monetary losses caused by extreme heat will hit people of color especially hard for many reasons, Dahl says. They are disproportionally represented in many outdoor jobs. The study shows more than 40% of U.S. outdoor workers identify as Black or Latino, despite being 32% of the general population. Additionally, she says, existing inequities have led these populations to have poorer health, such as higher incidences of underlying disease and less access to quality healthcare.

Farmworkers are particularly at risk as the danger of extreme heat is compounded by routine pesticide exposure, and farmworkers are 20 times more likely to die of heat-related causes than workers in all other civilian occupations, the CDC says.

Guidelines from the CDC and OSHA are only guidelines. Dahl says the U.S. has no enforceable national heat-safety standards to safeguard outdoor workers when temperatures turn extreme. Only California and Washington state have heat-safety standards.

To make working conditions safe, Dahl and Licker suggest employers try to reduce workloads and adjust schedules so work occurs during cooler times of the day. Their analysis showed by making that shift, it largely eliminated workers’ exposure to extreme heat and limited the potential financial repercussions of lost wages.

The authors admit there are practical limits to those adjustments, since emergencies can happen at any time and some construction work needs to be during the day. Still, she says, adjusting work schedules when possible was surprisingly effective.

However, that’s not the answer to the larger problem of climate change. Reducing global warming emissions is essential to limit the number of extreme heat days.

“If we fail to reduce our heat trapping emissions, millions of outdoor workers are going to increasingly be exposed to dangerous levels of heat. And in addition to the potential health impacts of that heat exposure, if workers aren’t paid for getting rest time on the job because it’s so hot, there’s $55 billion per year in outdoor workers earnings that’s at risk nationwide,” she says.

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