EPA helps communities plan for and respond to extreme heat to protect public health. Climate change is expected to increase the frequency, duration, and intensity of heat waves, affecting public health.

Increased daytime temperatures, reduced nighttime cooling, and higher air pollution levels associated with heat events can affect human health by contributing to:

• Respiratory difficulties
• Heat cramps
• Exhaustion
• Non-fatal heat stroke
• Death

Those most vulnerable to extreme heat are the elderly, very young children, infirm, poor, and socially isolated people, and those who are pregnant are at particular risk during heat waves.

People living in cities are already at a higher risk of heat waves because urban areas are warmer than surrounding non-urban areas due to the heat island effect. This may further compromise the health of vulnerable populations.