Oxygen: Health Effects and Regulatory Limits Part I: Physiological and Toxicological Effects of Oxygen Deficiency and Enrichment

Introduction Probably the biggest source of confusion and controversy involving confined spaces is the acceptable limit for atmospheres deficient or enriched in oxygen. This confusion and controversy has arisen, in part, because oxygen is essential for life, and because people can adapt in both the short-term and the longterm to oxygen levels both greater than and less than they are at sea level. Sea level, of course, is merely a convenient altitude of reference. There is no particular significance to this altitude, as people live and work quite comfortably at attitudes far below and far above this height.