PUBLISHED : Tuesday, 01 April, 2003, 12:00am
UPDATED : Tuesday, 01 April, 2003, 12:00am

In light of the increase in atypical pneumonia infections, I would like to ask the major airline companies what measures they are taking to reduce chances of cross-infection within the aircraft cabin, beyond barring visibly ill passengers from boarding.

I have heard that most aircraft do not operate the ventilation systems to allow outside air to enter the cabin at its maximum capacity - due to the cost of pressurising it and to reduce ozone levels.

This means that passengers and cabin crew breathe largely recycled air. Studies have shown that at cruising altitude, recycled air, even if filtered before reintroduction into the cabin, inevitably contains a higher count of particulates and potentially infectious agents than outside air.

I am aware that researchers have not proven a definite link between the incidence of infection being greater due to the recycling of air.

As it has not been conclusively disproved, however, I would be reassured to hear that the airlines are willing to vent their planes to a greater extent with fresh air, and that all recycled air is passed through standard airline filters which are serviced regularly.