Historical and Current Trends in Atmospheric Oxygen Content

Oxygen is vital for humans and animals. Nevertheless, until recently, undeservedly inadequate attention has been paid to trends and the variability of its content in surface air. This is due to the fact that the percentage of oxygen in the Earth’s atmosphere varies slightly, and measuring these small changes is rather difficult. However, even small changes in the oxygen content in inhaled air turn out to be quite significant for people, especially during heat waves, which are becoming more frequent and intensified in conditions of rapid climate change. This review is devoted to the history of knowledge about changes in oxygen content in the atmosphere and a review of research in recent decades, when the results of measurements of oxygen content in background and urban conditions became available.