Yale Program on Climate Change Communication

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June 2025 was the third-hottest June on record, continuing a trend of rising temperatures worldwide. Extreme heat is the leading cause of weather-related deaths in the U.S.—surpassing hurricanes and floods. Beyond causing direct illness, extreme heat exacerbates existing health conditions and increases the risk of workplace accidents.

Prolonged exposure to high temperatures, humidity, and heatwaves threatens the safety and livelihoods of outdoor workers like farmers, firefighters, and construction workers. An estimated 32 million workers in the United States work outdoors, and these workers are particularly likely to be male, Black, or Hispanic/Latino. From 2011 to 2020, over 33,890 U.S. workers suffered heat-related injuries or illnesses, and nearly 1,000 have died from extreme heat exposure since 1992, though underreporting is common. Extreme heat is also a global threat: Between 2000 and 2019, studies estimate that approximately 489,000 heat-related deaths occurred each year.

Beyond the health risks, extreme heat has enormous economic consequences. Without action, heat-related work disruptions could cost outdoor workers in the United States $55.4 billion annually by midcentury, impacting food production, construction, and supply chains. The crisis also deepens environmental injustices, disproportionately affecting Hispanic, Black, and low-income workers who often live in hotter areas with fewer cooling resources and limited access to healthcare. Farmworkers, many of whom are undocumented immigrants, are particularly vulnerable, often working in extreme heat with little ability to demand protections.

Climate change worsens these risks. Climate change is already causing more frequent and intense heat waves, which are expected to increase as the world warms further. For example, the number of days in the U.S. with heat indices above 105 degrees Fahrenheit are predicted to triple by midcentury compared with 20th Century averages.

Despite their high exposure to extreme heat, it is unclear whether communities with a larger proportion of outdoor workers are more worried about extreme heat. This Climate Note analyzes the relationship between the proportion of outdoor employment and worry about extreme heat across mainland U.S. counties and states using data from the U.S. Census and county-level estimates for heat worry in the 48 contiguous U.S. states and the District of Columbia. “Outdoor workers” are defined as individuals in occupations that regularly involve working outside — such as agriculture, construction, transportation, maintenance, and emergency services — using classifications from the “Too Hot to Work” project by the Union of Concerned Scientists (UCS). Importantly, this geographic-level analysis shows how the level of worry about extreme heat varies among counties with larger and smaller proportions of outdoor workers in the U.S. It does not directly measure whether outdoor workers themselves are more or less worried about extreme heat.

Outdoor Workers and Extreme Heat Worry by County

First, we compared the county-level relationship between the proportion of outdoor workers and the percentage of adults who are “moderately” or “very” worried about extreme heat. Using a population-weighted correlation coefficient, we found a modest positive correlation (r = 0.18), suggesting that counties with a larger proportion of outdoor workers tend to be more worried about extreme heat.

The relationship between the proportion of outdoor workers and worry about extreme heat, however, varies by region. The regions of the U.S. with the largest proportions of outdoor workers – the South and the West – also tend to have the highest levels of worry about extreme heat (r = 0.13 and r = 0.20, respectively). By contrast, in the Midwest and the Northeast, counties with larger proportions of outdoor workers tend to have lower levels of worry about extreme heat (r = -0.24 and r = -0.18, respectively). The Midwest in particular has much lower levels of worry about extreme heat compared with the West and the South, despite having only slightly smaller proportions of outdoor workers.

Outdoor Workers and Extreme Heat Worry by State

Finally, we used aggregated data to examine the correlations between outdoor employment and extreme heat worry at the state level. Overall, states with larger proportions of outdoor workers are more likely to be worried about extreme heat (r = 0.54). We also compared these findings to the list of states that have (or block) heat protections for outdoor workersMinnesota has also passed worker heat protection standards, but those standards only apply to indoor workers. and found that two of the states with the highest levels of worry (California and Nevada) have passed state-level heat protection standards, while other states (Arizona, Oklahoma, and New Mexico) have notThe city of Phoenix has adopted outdoor worker heat protection standards, but the state of Arizona has not.. Meanwhile, two states with large proportions of outdoor workers and high levels of worry about heat (Texas and Florida) have blocked localities from setting outdoor worker protections.

Key Takeaways

Using data from the U.S. Census and the Yale Climate Opinion Maps, we find that counties with larger proportions of outdoor workers tend to be slightly more worried about extreme heat, although worry about heat varies by region. Counties with larger proportions of outdoor workers—often rural and low-population—tend to report more worry about extreme heat, particularly in the South and West, where heat exposure is more frequent and industries like agriculture and construction dominate.

Notably, many places with larger proportions of outdoor workers have lower levels of worry about extreme heat, particularly in Western mountain states (such as Wyoming) and Midwestern states (such as North Dakota and Wisconsin). These regional differences may reflect historical differences in experiences with extreme heat, since the Midwest is usually cooler than the South. However, climate change is causing more extreme heat in places that have historically rarely experienced it, meaning that communication around extreme heat risks may be even more urgent in these areas.

These findings highlight the importance of tailored and multifaceted responses to extreme heat. While some regions face higher exposure, they may also be better equipped—through infrastructure, access to air conditioning, or formal protections—to mitigate risk. Our analysis shows that some states that have adopted heat safety standards also tend to have larger proportions of outdoor workers and levels of worry about extreme heat.

However, other states with similar proportions of outdoor workers and worry about heat have not adopted such standards, including high-risk states like Texas and Florida, which have actively blocked local worker protections like water breaks and rest periods.

Evidence from California shows that its 2005 heat standard, which mandates shade, water, and rest breaks on days over 95°F, is associated with a 30% drop in heat-related injuries. A nationwide heat standard proposed by Occupational Safety and Health Administration (OSHA) in 2024 could fill this gap, although it faces political and funding challenges. Expanding proven protections federally, along with robust enforcement, could protect millions of vulnerable workers.

Public health and occupational safety approaches adopted in other countries offer additional policy options for consideration. China mandates rest breaks, cooling measures, and High-Temperature Subsidies (HTSs) when temperatures exceed 35°C/95°F, while Costa Rica supplements standard protections with kidney health monitoring. Germany enforces indoor heat limits and ventilation requirements, and Qatar bans outdoor work when the wet bulb temperature exceeds 32.1°C/89.8°F. In South Africa, employers must provide medical monitoring and acclimatization plans when heat stress exceeds safe thresholds. Emerging technologies like wearable heat sensors and real-time environmental monitoring tools can further enhance workplace safety by enabling faster, targeted responses to dangerous conditions.

Improved education is also essential. Public health initiatives and workplace training can help workers identify signs of heat stress, engage in protective behaviors, and understand its connection to broader climate trends. Messaging that links personal experience with systemic drivers like climate change and emphasizes benefits of clean energy investment may be especially effective in politically resistant regions.

Methods

Scatterplots show the relationship between the proportion of outdoor workers and heat worry at the county level, and correlation coefficients are weighted based on total county population.

The population estimates of heat worry by county are drawn from the preprint, “Misalignment between assessed and perceived risks exacerbate vulnerability to extreme heat.” Detailed information about the mapping and estimation methods are provided here, and the original mapping estimation methods are provided here.

The population estimates of the share of outdoor workers by county and state are drawn from data from the U.S. Census Bureau’s American Community Survey (ACS) 5-Year Estimates and the Bureau of Labor Statistics (BLS) Occupational Requirements Survey (ORS) at the county and state level for 2023. The methodology follows the approach used in the Union of Concerned Scientists (UCS) 2021 paper, which examined outdoor employment and climate-related financial losses. The UCS study classified an occupation as “outdoor” if more than 65% of its workers were exposed to outdoors in any capacity in BLS ORS 2018. We applied this same standard to 2023 census data. These outdoor occupations include: protective service occupations; building and grounds cleaning and maintenance occupations; farming, fishing, and forestry occupations; construction and extraction occupations; installation, maintenance, and repair occupations; and transportation and material moving occupations.

Note: The share of workers in outdoor conditions has fluctuated over time, likely due to industry shifts and the impact of the COVID-19 pandemic on job settings. Notably, the classification of “transportation and material moving occupations” dropped from 70.6% outdoor in 2018 to 57.6% in 2023. However, we continued to classify this classification as an outdoor occupation in this analysis, both for consistency with UCS methods and because this classification involves substantial manual labor.