Question

Can humans survive lower temperatures when the pressure is lower

Answer 1

I think one cannot really separate the lack of oxygen from air pressure. Because the inside pressure balance the outside pressure, if the pressure is low outside, one cannot inhale lots of air without lung injury. Similarly, a scuba diver always inhale air at the pressure associated with its depth. (In consequence divers absorb much more oxygen (and consume more air) in deep water than in shallow water). You may eventually separate air pressure from oxygen if you consider someone who put a single arm or leg in a artificially very low pressure environment