The lowest natural temperature:
The lowest natural temperature ever directly recorded at ground level on Earth is −89.2 °C (−128.6 °F; 184.0 K), which was at the Soviet Vostok Station in Antarctica, on July 21, 1983.
Lower temperatures have been recording using laboratory equipment. To separate the gases in the air, it is cooled until in a fully liquid state, and then as it warms each gas will evaporate at it's boiling temperature. The method of fractional distillation of air is described here:
Air is filtered to remove dust, and then cooled in stages until it reaches –200°C. At this temperature it is a liquid. We say that the air has been liquefied.
Here's what happens as the air liquefies:
-water vapour condenses, and is removed using absorbent filters
-carbon dioxide freezes at –79ºC, and is removed
-oxygen liquefies at –183ºC
-nitrogen liquefies at –196ºC
-The liquid nitrogen and oxygen are then separated by fractional distillation.
Since air is 78% nitrogen, let's assume that below -196 degrees the air is mostly water and no longer a gas. Now, the effects of a temperature of -196 degrees on a human being's exterior:
Sudden changes of temperature can have health problems even in everyday scenarios:
"It dries off your skin, the mucus membrane and the eyes. We see patients who say they went to the malls or their offices and it was extremely cold. Eye infections, respiratory infections and muscular spasms are caused by this change in temperature,"
Assuming you have unlimited air constantly hitting the skin at -196 degrees (this is not possible with current techology, but maybe within your world it is), it is safe to say that the exterior of the body would cool rapidly. This would cause water in the skin cells to freeze and expand, rupturing the cells. This would kill all cells exposed to the blast. The longer you freeze, the more deeply this will go into the body. There would be no bleeding, since cells would freeze together, however the expanding of the water may be enough to crush parts such as capillaries. If a major vein or artery close to the skin's surface were to block due to freezing, blood flow would be severely restricted, removing most of the oxygen supply to the body; the effects of this are severe. Stopping blood flow will likely result in a heart attack, and if the heart stops altogether, this results in sudden cardiac arrest:
Sudden Cardiac Arrest (SCA): also known as sudden cardiac death, this is when the heart suddenly and unexpectedly stops beating and blood stops flowing to the brain and other vital organs. SCA usually causes death if not treated in minutes.
In short, freezing will leave the victim unable to move or resist, and dying. With most of the external parts destroyed by freezing and a case of sudden cardiac arrest, the victim will die within minutes.