Quote:
Australian 10,000m runner Ron Clarke had to be revived through the use of an oxygen mask after collapsing from altitude sickness in Mexico City at the 1968 Olympics
Oh come on, you don't get altitude sickness at 2000m, it's not that high. Plane cabins are pressurised to emulate an altitude of more or less that. My wife is from nearby Toluca, which is 2700m above sea level, and there you do feel it a bit going up flights of stairs sometimes, but it's not really the High Andes or Himalayas.
The smog in Mexico City may be more of a factor than the altitude.