Speaking after a London conference on the subject, Professor Martin Hocking said modern aircraft did not pump enough clean air into passenger cabins.

``The filters that are used are very efficient, but there are still risks of the smaller particles, such as viruses, coming through,'' Hocking, of the University of Victoria in Canada, told Reuters.

``And the filter does nothing to increase the oxygen levels, or decrease the carbon dioxide levels in the recycled air,'' he said, adding this could increase the risk of disease transmission.

Tuberculosis was among the diseases passengers could contract, though Hocking said the risk was slight. ``It is not so readily transmissible as some other illnesses such as flus and colds,'' he said.

Tuberculosis, which is endemic in some parts of the world, spreads through airborne bacteria, and can be caught by breathing air affected by an infected person's coughing or sneezing.

But people grouped in a confined space always face a certain amount of risk, Hocking said. ``I don't think anything (the airlines) could do would completely avoid it, because any place where people are gathered in close proximity will be at risk,'' he said.

``But if they could increase the outside airflow, if they could decrease the filter change interval, it should improve the (situation).''

Tim Goodyear, of the International Air Transport Association, rejected suggestions that airlines were saving money at passengers' expense.

He told BBC radio that cabins received a steady influx of fresh air amounting to 10-15 full exchanges of air every hour.

``The new-generation Boeing and Airbus aircraft are equipped with highly efficient particulate air filters similar to those used in hospitals and high-tech manufacturing, and that prevents the transfer of infectious organisms,'' Goodyear said.

Reference Source 89

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