At some of the world’s highest observatories, fresh air is not necessarily safe air. The Atacama Large Millimeter/submillimeter Array, better known as ALMA, operates on Chile’s Chajnantor Plateau at approximately 5,000 metres above sea level. At that altitude, air pressure is roughly half what it is at sea level, meaning every breath delivers far less oxygen to the body. Simple tasks become exhausting, concentration can deteriorate and prolonged exposure may lead to serious a