This article was written by UHC Faculty Member Leah Schinasi and Dornsife Graduate Research Assistant Tina Duong Nguyen as a part of the UHC's "Hot Topics in Urban Health Policy" Blog Series. It is based on a new study authored by Tina Duong Nguyen and Co-Authored by Data Analyst at Dornsife Joe Simeone, Leah Schinasi, and UHC Faculty Member and Policy Core Co-Lead Alina Schnake-Mahl.
Philadelphians would agree: it’s been a brutally hot summer. So far in 2026, the city has experienced seven heat waves. The most recent swept the region in late August/early September, resulting in early closures for 52 of the city’s public schools that lack adequate cooling. Although disruptive for families, these actions may protect health. Heat exposure can cause a laundry list of health symptoms—headache, dehydration, nausea, vomiting, muscle tightness, and difficulty breathing. It can also be fatal; Philadelphia’s early July 2026 heat wave caused at least seven deaths. Yet, heat is not always treated as a hazard, and protections are not always granted to those who need them the most.
When temperatures soar, those with access to shade, air conditioning, and protections can retreat from the heat. Others have far fewer options and may be left to literally ‘sweat it out,’ sometimes suffering deadly consequences. Take, for example, people who work outdoors or in hot indoor settings—like those working in agriculture, construction, landscaping, manufacturing, municipal or postal services, or food service industries. For many of these workers, extreme heat does not mean the work stops. Researchers estimate that, in 2023, temperatures higher than 70°F contributed to 27,953 excess injuries among U.S. workers. And, from 1992-2021, an estimated 999 occupational fatalities among workers were associated with heat exposure.
Heat-related occupational injuries and fatalities are preventable.
Measures such as taking breaks, drinking water, and allowing those who are unaccustomed to heat to slowly adjust (acclimatize) can protect health and save lives. In many workplaces, however, these practices are inconsistent with expectations, pay structures, or culture. In some contexts, they are frowned upon or prohibited.
Mandated workplace regulations can help establish a culture of heat safety.
In 2005, California became the first state to require heat illness prevention measures for outdoor workers (CCR Title 8, §3395). This standard requires employers to provide drinking water, shade, cool-down areas, training, acclimatization, emergency response procedures, and written heat illness prevention plans when temperatures reach 80°F. Above 95°F, employers must take additional precautions, including monitoring workers for symptoms and encouraging water and rest breaks. California extended similar protections to indoor workers in 2024 (T8CCR §3396). Since 2005, several other states have adopted heat-safety standards, with varying requirements, temperature thresholds, and worker and industry coverage.
In the U.S., there is no federal heat-illness prevention standard for workplaces.
In 2024, OSHA published a Notice of Proposed Rulemaking for heat injury and illness prevention in outdoor and indoor work settings. As of this writing in 2026, the rule has not been promulgated. While many stakeholders and workers are supportive of the rule, some industry representatives have expressed concern that such a policy will harm economic activity.
Motivated in part by these concerns, in research published in the journal Environmental Research Letters, we evaluated California’s 2005 heat illness prevention standard. We analyzed county- and industry-level payroll data from 2000–2010 in industries covered by the standard—agriculture, mining, construction, and transportation/warehousing—and examined the relationship between annual days above 80°F and 90°F and per capita payroll, a proxy for economic activity.
We asked two questions: Did more hot days reduce economic activity, and did California’s heat-safety standard change that relationship?
Before the standard was adopted, each additional day above 80°F was associated with a modest reduction in per capita payroll. After adoption, this relationship remained similar or became slightly less negative, suggesting that the standard did not adversely affect economic activity during hot weather.
Because other factors could have influenced these trends, we conducted the same analysis in Oregon, which did not have a heat-safety standard during the study period. Trends in Oregon were not markedly different from those in California, meaning we cannot attribute California’s findings solely to the policy.
Our observational study cannot establish causation or determine whether the findings apply elsewhere. Nevertheless, we found no evidence that California’s heat-safety standard harmed business economic activity during hot weather.
Most importantly, in our analysis, we did not quantify the impacts of the heat safety standard on the most precious outcomes of all: human life, well-being, and quality of life. Future work should estimate the total effects of these standards, incorporating health outcomes and the economic value of prevented illness or death in addition to business activity. These heat safety standards have the potential to be a true win-win.