The long read (Revolution in the air: how laughing gas changed the world, 4 July) provides an insightful journey that nitrous oxide has taken: “Since its discovery in the 18th century, nitrous oxide has gone from vaudeville gimmick to pioneering anaesthetic to modern party drug.” However, the article does not inform us about its harmful effects on the environment. Nitrous oxide is now an environmental villain. It contributes significantly to climate change and is now the most important cause of damage to the ozone layer. It has 300 times the global warming potential of carbon dioxide and is only broken down slowly, remaining in our atmosphere for over 100 years. Remarkably, Entonox (a mixture of nitrous oxide and oxygen) used for childbirth is still present when that child reaches 100 years of age. Nitrous oxide, once a fundamental ingredient in anaesthesia, is no longer required in anaesthesia except in maternity anaesthesia, and so many hospitals are now decommissioning their nitrous oxide manifolds where possible. Prof Pete Ford Consultant anaesthetist Dr Hemal Bosamia Anaesthetic trainee Royal Devon and Exeter hospital