The &quot;cold and lack of oxygen&quot;? How about just altitude sickness?<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Altitude_sickness" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Altitude_sickness</a>