You wouldn’t notice it at first. But every second, the air around you is thinning, just a little. Within 30 seconds, you’d be gasping. Engines would fail, hospitals would go dark, and planes could crash. Oceans would suffocate, and the sky would turn deadly. If Earth started losing just 1 percent of its oxygen every second, this is how fast the world could end.But how long would it take to completely run out? Could anything survive in a zero oxygen world? And could humans ever hope to repopulate the planet?The First 10 SecondsAt first, the change is barely noticeable. With 90 percent of oxygen remaining, the air might feel slightly thinner, similar to the sensation of hiking at high altitude. For elite athletes or anyone sensitive to oxygen levels, even this small drop could make the body feel exhausted from simple exertion.Meteorologists and scientists monitoring the atmosphere would be the first to notice the strange readings. In the time it takes to report an emergency, another 20 seconds would have passed, and oxygen levels would continue their rapid decline.30 Seconds In: A Dangerous DropBy half a minute, 26 percent of the world’s oxygen would be gone. That 21 percent of oxygen we take for granted would now be just 16 percent. At sea level, people would start gasping for air, hyperventilating to get enough oxygen. Those living at high altitudes, such as Aspen, Colorado, would have an easier time they’re already acclimated to thinner air.Hard labor would become unbearable. Construction workers would sweat and struggle to coordinate, factory operators might make dangerous mistakes, and hospitals could descend into chaos. Patients with heart or lung conditions could die as oxygen levels in the air and in their bodies plummet.Animals would suffer too. Birds, which rely on high oxygen to sustain flight, would start falling from the sky. Plants, which also need oxygen to burn energy, would be forced into alternative, less efficient metabolic pathways. Fires would sputter or die out entirely, power grids would falter, and combustion engines from cars to airplanes would fail. Planes would fall from the sky, and cars would stall in the streets.One Minute: Half of Our Oxygen GoneA minute in, and 50 percent of the oxygen has vanished. Humans would struggle to breathe, with short, shallow breaths. Blue lips and confusion would be common as oxygen starvation affects the brain. The chaos on the streets would be unimaginable emergency sirens blaring, vehicles stranded, and people collapsing.The oceans would begin releasing dissolved oxygen, suffocating marine life. Fish and other sea creatures would die rapidly as oxygen levels drop below what they need to survive. The ozone layer would start to degrade, exposing the planet to harmful UV radiation, though few would survive long enough to feel its effects.Two Minutes: Life CollapsesAt two minutes, 70 percent of oxygen is gone. Humans, animals, and plants would begin to fall unconscious, faces ashen. This level of oxygen depletion would trigger a mass extinction event comparable to the one 550 million years ago that wiped out 80 percent of life. Plankton, which produce much of the planet’s oxygen, would die, accelerating the crisis.Infrastructure reliant on combustion engines or oxygen dependent processes would crumble. Fossil fuel energy would fail, leaving only solar and hydroelectric power functional. But with humanity gone, even this energy would go unused.8 Minutes: A Planet Without OxygenEight minutes after the start, 99 percent of oxygen would be gone. Humans and animals would not just be dead they would disintegrate as oxygen in their bodies vanished. The Earth itself would be unrecognizable: oceans reduced to hydrogen rich water, buildings crumbling as oxygen disappeared from concrete, and life entirely extinguished.Could Earth Recover?If oxygen were removed from every compound on Earth, recovery would be impossible for billions of years. But if only atmospheric oxygen disappeared, some life could survive. Anaerobic bacteria, which thrive without oxygen, would flourish, echoing the earliest stages of life on our planet.Even if oxygen somehow returned to the atmosphere, the majority of life would remain extinct. The human population, wildlife, and plant life would be wiped out, leaving behind a silent, empty planet.