1400 years ago, it was not known that altitude affects breathing, but this fact was described in the Quran.

As altitude increases, atmospheric pressure decreases, which means there is less oxygen available to breathe. Above a certain height, the oxygen levels are too low to sustain human life. This is known as the "death zone" in mountaineering, which starts around 8,000 meters (26,000 feet). At this altitude, climbers need supplemental oxygen to survive.

The higher you go, the harder it becomes to breathe because of the drop in atmospheric pressure and oxygen concentration. This is why mountaineers need oxygen tanks in the death zone.

The Quran mentions this difficulty in breathing due to altitude, describing how those who reject faith feel as if their chests are constricted, "as if they are ascending to the sky":

The description of chest tightness and difficulty in breathing, likened to ascending into the sky, aligns perfectly with the challenges of breathing at high altitudes. This was only understood in modern times, but it was accurately described in the Quran over 1400 years ago.

The Quran’s description of how a person's chest feels tight as they "ascend to the sky" matches the scientific understanding of how altitude affects breathing. This demonstrates the remarkable insight in the Quran, long before it was discovered by modern science.