Intersegmental differences in facial warmth sensitivity during rest, passive heat and exercise

Area of Science:

• Human physiology
• Environmental science
• Thermal comfort research

Background:

• Facial warmth perception can influence overall thermal discomfort.
• Different facial regions exhibit distinct temperature profiles.
• Understanding regional facial warmth sensitivity is crucial for thermal comfort studies.

Purpose of the Study:

• To investigate differences in facial warmth sensitivity across various facial regions.
• To analyze these differences under thermoneutral, warm, and exercise conditions.
• To determine the relationship between facial temperature and perceived thermal comfort.

Main Methods:

• Heat flux measurements were taken on six facial regions of twelve men.
• Participants underwent rest in thermoneutral (25°C) and warm (40°C) conditions.
• Exercise (400 W metabolic heat production) was performed in a 40°C, 30% RH environment.

Main Results:

• Forehead showed the highest temperatures; nose and chin showed the lowest depending on conditions.
• Warmth sensitivity varied significantly across facial regions, with the upper lip being most sensitive.
• Perceived thermal comfort was more strongly correlated with mean facial temperature (Tface) than core temperature (Tco) or overall body thermal sensation.

Conclusions:

• Regional differences in facial warmth sensitivity exist and influence thermal perception.
• Facial temperatures tend towards equilibration during heat-producing activities.
• Facial temperature is a more significant predictor of thermal comfort than core temperature or overall body thermal sensation.