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Pollution increases heat-related farmworker danger

farmworkers heat

Official statistics greatly underreport heat-related deaths among farmworkers in California’s San Joaquin Valley, according to a study by Inside Climate News.

Statistics from California’s Division of Occupational Safety and Health (Cal/OSHA) show that only one farmworker in the state died from heat-related causes in 2022: “To date for CY 2022, Cal/OSHA is aware of one medically confirmed fatality case related to outdoor heat exposure, but as of this writing, other suspect heat-related fatalities are pending medical evaluation.”

Headshot of Richard Smoley

The same report indicated one heat-related death in 2021.

But a review of federal farmworker death records, “along with temperature and air pollution data, suggests the numbers may be much higher,” says Inside Climate News. “Scores of farmworkers died in California between 2018 and 2022 when temperatures exceeded the threshold that triggers California’s heat safety requirements. All of these deaths occurred in counties with chronically unsafe air.”

Heat combined with heavy air pollution contributes to farmworker deaths, even though the cause of death may be listed as heart attack, stroke, dehydration, or even accidents with machinery, of which there is a higher risk in hot conditions.

“If a worker hadn’t been working in the heat,” says Daniel Smith, an assistant professor at Villanova University’s College of Nursing, “they likely would have never died from the myocardial infarction, the renal failure, the dehydration, the heat stroke.”

The San Joaquin Valley has been called the world’s most productive agricultural region. But it has also had the nation’s highest rates of PM2.5 particle pollution. (PM2.5 particles are those too small to be detected by an ordinary microscope.)

“Despite the progress made to improve the Valley’s air quality through implementation of multiple attainment plans adopted by the District and clean air investments by Valley businesses and residents, substantial additional emissions reductions are needed,” says a report from the San Joaquin Valley Air Pollution District.

“California was the first of the five states that have passed a heat exposure standard, and its requirements are considered among the toughest,” says Inside Climate News. “Yet the standard doesn’t recognize an increasingly dangerous threat for agricultural laborers in a warming world: working in hot, polluted air.”


Richard Smoley, contributing editor for Blue Book Services, Inc., has more than 40 years of experience in magazine writing and editing, and is the former managing editor of California Farmer magazine. A graduate of Harvard and Oxford universities, he has published 12 books.