Areas at higher elevations have less oxygen due to lower air pressure.

At higher elevations, air pressure decreases, resulting in a lower concentration of oxygen molecules. As altitude increases, the atmosphere becomes thinner, meaning there is less air above exerting pressure, so the air density (including oxygen content) diminishes. Although the percentage of oxygen remains the same (about 21%), the reduced air pressure means fewer oxygen molecules are available per breath, making it harder to obtain the oxygen needed for normal bodily functions. This phenomenon can lead to altitude-related challenges, such as shortness of breath and altitude sickness, especially in high mountain regions.