Overview

• Studies show high humidity impairs sweat evaporation and worsens heat stress beyond temperature alone.
• Penn State experiments set wet-bulb safety limits at around 88°F for younger adults and as low as 82–83°F for older individuals.
• Older women face greater risk than men at similar ages due to declines in sweating efficiency, skin blood flow and cardiovascular strain.
• Electric fans can exacerbate heat risk when indoor temperatures exceed 95°F by blowing hot air over the body.
• Experts recommend seeking air-conditioned or shaded spaces, hydrating with water and water-rich fruits, and gradually acclimatizing to outdoor heat.