“In your house you will have a fire detector and a carbon monoxide detector,” he said, “you will find air quality detectors in mines, submarines and spacecraft – in any enclosed space where you can’t simply open the door – but not planes. I personally think it’s because the air industry won’t like what they find.”

New technology promises new air filters

The way in which air is circulated around a plane cabin is beginning to change thanks to new technology, such as that used in Boeing’s recent Dreamliner planes.

When commercial flights began in 1958 passengers breathed in air supplied directly from the atmosphere using compressors.

But this was deemed to be too expensive, so in 1962 a system was installed to draw the air from the heart of the engines — known today as “bleed” air.

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The vast majority of commercial passenger planes being flown today use the “bleed air” system. Air is drawn out of the compression section of the engine and cooled. It then enters the cabin, where it mixes with recirculated air that has passed through filters designed to remove bacteria and viruses. These “recirculated air” filters do not remove any fumes or vapors from the engine. So if engine oil or hydraulic fuel leaks, because of poorly designed or faulty seals, or even overfilled tanks, toxic chemicals can contaminate the air supply.

In contrast, Boeing’s new Dreamliner pumps fresh cabin air from a separate source (away from the engines) for the first time since the Fifties.