High concentration oxygen therapy has long been a mainstay of prehospital treatment. Guidelines for its administration have for many years also cautioned its use with patients with chronic obstructive pulmonary disease (COPD). Successive guidelines and prehospital textbooks have advocated the use of 28% oxygen masks and re-emphasised the importance of the dangers of hyperoxia, often drawing upon the classic theory of hypoxic drive. Despite this, the reality remains that ambulance crews have tended to overoxygenate such patients. One study demonstrated that 80% of patients sampled with acute exacerbation of their COPD received oxygen in excess of 28% from the ambulance crew. Is this a worrying development or a reassuring sign that prehospital providers are rightly more concerned about the dangers of hypoxia than hyperoxia? And if the guidelines are right, then how are the hearts and minds of ambulance paramedics and technicians won?