How long does it take for frostbite to take full affect?

Answer 1

The occurrence of frostbite is dependent on the environmental temperature, wind-chill, dampness, immersion, and the amount of clothing worn by the individual. Frostbite is caused by blood being shunted away from the affected area secondary to the cold injury. Treatment for frostbite is essentially re-warming the damaged area with a hand, for example.

Answer 2

Depending on conditions, anywhere from a couple of minutes (even down to a few seconds in extreme situations) to a few hours.

Important factors include: Ambient temperature, wet vs dry skin/clothing, and wind speed/wind chill factor, and maintenance of the body's core temperature/blood flow to the extremities.

Ambient temperature is essentially what you read on the thermometer, without regard to wind speed or humidity. Frostbite occurs when exposed tissue freezes to a degree that causes tissue damage. As such, the ambient temperature must typically be at or near freezing for there to be a risk of frostbite. Typically, the lower the ambient temperature, the higher the risk of frostbite.

Wet skin freezes faster than dry. This is because evaporation of moisture cools the underlying surface (an asset in hot conditions when you sweat, but a liability in cold conditions). Also, cold moisture on the skin makes it take more energy per unit of surface area for the body to re-heat cooling tissue.

Wind pulls heat away from the skin quickly by moving away the layer of warmer air next to the skin and replacing it with cooler air (a greater difference in temperature between skin and air leads to faster transfer of heat energy out of the skin). If skin is damp, moving air increases the rate of evaporation, which in turn increases the rate of evaporative cooling. The faster the wind, the higher the rate of cooling.

Wind Chill Factor is a rating given by meteorologists in terms of an equivalent ambient temperature. For example, if the ambient temperature is 35F, but the wind is blowing at 30 mph, the felt temperature or wind chill is about 22F - easily cold enough to freeze exposed skin.

Core temperature's relationship to frostbite is not at first apparent. However, if the core of the body begins to cool, the body's natural reaction is to constrict blood vessels, reducing blood flow (and thus heat distribution) to the extremities, in order to maintain operating temperature around critical organs in the core (heart, lungs, brain) for as long as possible. For this reason, your fingers may go numb due to lack of oxygen before you get actual frostbite.

Inadequately protected core temperature also makes one more vulnerable to frostbite due to reduced blood flow, as does reduced bloodflow due to: constricted clothing (too many layers of socks in tightly-laced boots/skates), inactivity, and certain medical conditions like Diabetes.

In still air, with dry skin, at an ambient temperature of say 35 degrees, a normal healthy individual might have little to no risk of frostbite, even in a t-shirt and shorts.

Add in high winds and wet snow, however, and such a person could experience frostbite in half an hour or less (not to mention hypothermia).

Stepping out the front door into a high wind when ambient temps are hovering around -40F could result in frostbite in a minute or two without protection.

Skin exposed directly to something like liquid nitrogen or dry ice (frozen carbon dioxide) can experience frostbite in mere seconds.

Answer 3

Roughly 9 minutes to exposed skin, assuming there is strong wind.

Answer 4

No one knows for sure.