I think you badly misread your source. 8.5 _minutes_ survival time does not even pass the smell test. At -20C in room-temperature clothing and without complicating factors (e.g. wind chill or rain), survival time is going to be on the order of 12 hours.
However, if you combine -20C temperature with hypoxia, things are going to turn badly much faster.
Yes, misread M for H in the abstract. The NIH number is 8.6 hours at -20C with two layers of loose clothing. Recovery time after several hours of -20C is fairly lengthly.