About Heat and Its Impact on Communities

By the mid-21st century, California is projected to experience a significant rise in daily maximum temperatures, with an increase of 4.4ºF – 5.8ºF above the 1950 average. Heat waves, which are already a growing concern, are expected to last up to two weeks longer in regions like the Central Valley and occur 4 to 10 times more frequently in areas such as the Northern Sierra. In urban centers, heat-related deaths are projected to triple, disproportionately affecting vulnerable and marginalized populations.

The health impacts of extreme heat are not felt equally across communities. Social determinants of health—such as income, access to resources, and living conditions—play a critical role in how well individuals can cope with rising temperatures. The impact of extreme heat is further compounded by long-standing systemic inequities, including racial and environmental injustices, that leave certain communities more exposed and less resilient.

Health Impacts and Disproportionate Vulnerabilities

Extreme heat is a public health threat, especially for individuals living in already disadvantaged circumstances. Vulnerable groups—such as children, elderly people, outdoor workers, individuals with chronic health conditions, and communities that have limited access to cooling or shade—are at a greater risk of heat-related illness or death. This disproportionate impact stems from a combination of social, economic, and environmental factors.

Communities of Color and Environmental Injustice

Racial and ethnic minorities, particularly those in low-income neighborhoods, face higher exposure to extreme heat due to a legacy of discriminatory policies, such as redlining, and the ongoing effects of environmental racism. These policies have shaped the built environment, leaving these communities with fewer green spaces, less access to cooling resources, and greater exposure to urban heat islands.

For example, communities historically subjected to redlining are often found in areas with fewer trees, less vegetation, and higher levels of heat, which exacerbate the risks of heat-related health impacts. Structural inequalities in housing and urban planning further decrease the resilience of these communities to climate impacts like heatwaves.

Outdoor Workers

Outdoor workers, particularly those in agriculture, construction, and other manual labor jobs, are also at heightened risk during extreme heat. Prolonged exposure to high temperatures can lead to dehydration, heat stress, and even heat stroke, significantly impacting workers' health and safety. These workers can have limited access to workplace protections, including adequate rest breaks, cooling spaces, or health benefits. Their ability to mitigate heat exposure is constrained by the social determinants of health, including economic hardship and lack of resources.

People Without Access to Air Conditioning or Cooling Spaces

For individuals who lack air conditioning or live in homes with inadequate cooling, heat can be a life-threatening issue. This is especially true for people living in older housing units or for those facing financial constraints that make air conditioning inaccessible. Cooling centers and community-based resources may be out of reach for many low-income individuals, further intensifying their vulnerability.

Disproportionate Health Impacts on Specific Populations

  • Young Children and Older Adults: Both the youngest and eldest age groups are particularly vulnerable to extreme heat. Elderly adults may have underlying chronic health conditions or take medications that affect their ability to regulate body temperature. Children, on the other hand, are less able to recognize early signs of heat stress and rely on caregivers for protection.
  • Pregnant People: Pregnant individuals may experience more difficulty in regulating body temperature, increasing their risk during extreme heat. It is vital to ensure that these individuals have access to cooling resources and clear health guidance during heatwaves.
  • Chronic Illness and Disability: Those with chronic conditions like respiratory or cardiovascular diseases, as well as individuals with disabilities, are at a higher risk of experiencing severe health effects due to extreme heat. Their ability to seek care or access cooling resources is often limited by economic barriers, physical accessibility issues, and a lack of tailored public health information.
  • People Experiencing Homelessness: Homeless individuals are particularly vulnerable during heatwaves due to their lack of access to shelter, cooling systems, and access to hydration. The lack of access to stable housing exacerbates their exposure to extreme heat, and many face compounded health risks due to existing chronic conditions or other vulnerabilities.
  • Linguistically Isolated Households: People who speak little to no English are often excluded from critical health alerts and public safety messages, leaving them ill-prepared to respond to extreme heat events. This language barrier further deepens inequities in heat preparedness and response.
  • Individuals Without Health Insurance: Individuals without health insurance may feel greater health impacts due to a reduced ability to access medical treatment. Extreme heat and other climate disasters leaves those without health insurance particularly vulnerable.
  • Athletes: High-exertion exercising during extreme heat can increase the risk of dehydration, heat-illness, and death.