Alternating measurement of ambient and cabin ozone concentrations in commercial jet aircraft.

Ambient and cabin-air ozone concentrations were determined with an adapted commercial ozone analyzer installed in a KLM DC-10 from Amsterdam to Toronto and back. Cabin levels were detected directly and almost continuously; ambient levels were measured using a sampling system in which the ambient samples were converted to the cabin pressure at intervals of 13 min. A correlation is demonstrated between the ambient level, the cabin level, and the tropopause height. It was found that 70% of the ambient ozone concentration enters the cabin through the ventilation system, and about 50% of this concentration was measured 1.20 m above the cabin floor. For about 50% of the total flying time, the ozone level exceeded 200 parts per billion, by volume (ppb) in the cabin, with peak concentrations of about 600 ppb (TLV levels of 80--100 ppb apply in most IATA countries). Finally, medical and technical recommendations are made for future measurements.