Over one billion people fly on commercial aeroplanes each year, and taking young children abroad on holiday is an expected part of modern life in the United Kingdom. This article considers the issue of whether it is safe for infants and young children to fly, and reviews the hazards. It principally focuses on issues of hypoxia and respiratory disease but also reviews other areas (box 1). The British Thoracic Society 2004 guidelines1 suggest that “it is prudent to wait for 1 week after birth before allowing infants to fly to ensure they are healthy”, which is similar to the international Aerospace Medical Association, which suggests waiting 1 to 2 weeks after birth.2

HYPOXIA DURING AIR FLIGHT

The greatest concern is the effect of hypobaric hypoxia (hypoxia caused by a lowered oxygen pressure at altitude). Commercial aeroplanes fly at an altitude of 30–40 000 ft (9144–12 192 m), which would result in an equivalent fraction of inspired oxygen (FiO₂) of only 0.04 (as opposed to 0.21 at sea level). To counteract this, aircraft cabins are pressurised so that the passengers are at the equivalent of 5–8000 ft (1525–2438 m); at this level the air has an equivalent FiO₂ of 0.15–0.17. US Federal Aviation Regulations stipulate that cabins must not be pressurised to above 8000 feet (around 560 mm Hg), and if the cabin altitude rises above this, emergency oxygen masks are deployed automatically. It is theoretically possible for aircraft to be maintained at a sea-level pressure (760 mm Hg), but this would be less energy- and no doubt …