Breathing at Everest's Summit vs. the Sahara Desert

Breathing is far more difficult at the summit of Mount Everest than in the Sahara Desert. The reasons:

• Air pressure: At sea level, pressure is ~14.7 psi. At Everest's summit (29,032 ft), it's only ~0.33 psi. The Sahara, at low elevation, has near-sea-level pressure.
• Oxygen availability: While oxygen remains ~21% of the air, the low pressure at altitude means far fewer oxygen molecules per breath, leading to hypoxia and altitude sickness.
• Cold temperatures: Everest's summit can reach -60°F; cold air is denser, requiring more effort to inhale.
• Low humidity: Extremely dry air irritates airways.

In contrast, the Sahara's low elevation, higher pressure, warmer temperatures, and moderate humidity make breathing comparatively easy.