Freezing temperature of finger skin

Area of Science:

• Environmental Physiology
• Dermatology
• Biophysics

Background:

• Frostnip and frostbite are risks in cold environments.
• Skin supercooling precedes ice crystallization and tissue damage.
• Understanding freezing points is crucial for cold injury prevention.

Purpose of the Study:

• To determine the apparent freezing point of skin under varying wind conditions.
• To analyze the relationship between supercooled skin temperature and the apparent freezing point.
• To compare the apparent freezing point with the true freezing point of skin.

Main Methods:

• Inducing frostnips in 45 subjects by cooling fingers in -15°C air with controlled wind speeds.
• Measuring skin temperatures during cooling and ice crystallization.
• Calculating apparent freezing points and comparing them using analysis of covariance.

Main Results:

• Mean supercooled skin temperature at frostnip onset was -9.4°C.
• Mean skin temperature rise due to heat of fusion was 5.3°C.
• Apparent freezing point decreased with increasing wind velocity, though not always statistically significant.
• The highest calculated apparent freezing point was significantly lower than the true freezing point determined in brine.

Conclusions:

• Wind significantly affects the apparent freezing point of skin.
• The apparent freezing point is lower than the true freezing point, especially at higher wind speeds.
• These findings highlight the increased risk of cold injury in windy conditions.