The air differs as you move greater and higher in to the atmosphere. The air receives "thinner" as elevation climbs for the reason that there are actually fewer air molecules up there. Mountain climbers typically have to use canisters of oxygen since they climb earlier mentioned 3,800 meters (12,500 toes) https://www.dailypioneer.com/2025/page1/smoke-smell--unruly-passenger-affects-ai-flight-service.html