Salty Skin Boosts Cooling Efficiency, ASU Research Finds

Human survival in extreme heat depends on the body's ability to shed warmth, a process that relies heavily on the physics of sweat. New research from Arizona State University suggests that the presence of salt on the skin is a primary driver in making this cooling process more efficient.

Konrad Rykaczewski, an associate professor at ASU, led a team that utilized a first-of-its-kind outdoor thermal manikin named ANDI to analyze how the body cools under intense thermal stress. The study found that salty skin significantly enhances cooling efficiency. According to Rykaczewski, "We found that the biggest factor that helps the body cool faster is salty skin."

The team discovered that salt crystals act as a catalyst for wicking. Rather than allowing sweat to gather in small, inefficient puddles, the salt allows new sweat to spread immediately into a thin film across the skin's surface. This expansion increases the total surface area available for evaporation, which is the critical mechanism by which the body releases heat into the environment.

The Mechanics of Evaporation

While the biological process of generating sweat is well-documented, the actual physics of how that sweat evaporates from the skin has remained largely unexplored until now. To bridge this gap, Rykaczewski's team employed a suite of advanced imaging and diagnostic tools. They used mid-wave infrared cameras and optical coherence tomography microscopes to observe sweat as it emerged from pores and interacted with the skin's surface, while miniaturized wind tunnels simulated various environmental conditions.

Implications for Heat Safety

These findings arrive as heat-related mortality becomes a pressing public health crisis. The urgency is underscored by data from Maricopa County, which recorded 608 heat-related deaths in 2024. Understanding the precise mechanics of evaporative cooling is essential for developing better survival strategies and protective equipment for those exposed to extreme temperatures.

Rethinking Athletic Gear

The research also challenges prevailing trends in the apparel industry. Many modern athletic clothing lines are designed to pull sweat away from the skin to keep the wearer dry and comfortable. However, the ASU study suggests that this priority on comfort may come at the expense of maximum cooling efficiency. By removing the moisture from the skin's surface, such fabrics may interfere with the thin-film evaporation process that salt crystals help facilitate.

Future Applications

Moving forward, this research could pave the way for a new generation of clothing and tools specifically engineered to optimize the skin's cooling capacity. By mimicking the wicking properties of salty skin, developers may be able to create materials that maximize surface area for evaporation, providing a critical advantage for athletes, outdoor workers, and emergency responders operating in lethal heat.