Quantifying the Global Population Residing at Different Altitudes

Abstract

Human adaptation to low oxygen at high altitudes has been extensively studied, with adaptations categorized as metabolic or respiratory. Altitudes are commonly classified into different ranges (low,18 moderate, high, and very high), yet quantifying the global population exposed to these elevations remains challenging due to population dynamics. This study aimed to quantify the global population living at different altitude ranges and to describe its distribution using geospatial and population databases. We conducted a global ecological analysis using data from the World Cities Database (Pro version, refreshed May 11, 2025), GPS elevation data from the dCode tool, and NASA’s Shuttle Radar Topography Mission (SRTM). Over 1.8 million cities were classified according to two altitude categorizations: the classical classification of low (<2,500 m) and high (≥2,500 m) altitudes, and the International Society for Mountain Medicine (ISMM) classification (low: <1,500 m, moderate: 1,500–2,500 m, high: 2,500–3,500 m, very high: 3,500–5,500 m). The analysis revealed that 99.26% of the global population (~7.95 billion) lives below 2,500 meters, where 98.86% of cities are located. In contrast, only 0.74% of the population (~57.8 million) resides above 2,500 meters, with significant concentrations in the Andes, Himalayas, and Ethiopian Highlands. Population density declines sharply as altitude increases. The vast majority of the global population resides below 2,500 meters. These findings provide a crucial foundation for understanding how altitude influences population distribution and highlight the need for further research into the health impacts of high-altitude living. This study offers insights for public health strategies aimed at mitigating altitude related health risks.