TB link to air on planes

THE US government is investigating claims that tuberculosis can be transmitted through the cabin air of passenger planes.

An inquiry ordered by transportation secretary Federico Pena is studying four cases of TB, three involving passengers on international flights and the other a flight attendant with active TB who apparently gave it to other crew members. Passengers on the flights are being traced.

The Centres for Disease Control will try to assess whether the aircraft's air circulation systems were to blame, as well as examining the dangers from other airborne viruses, bacteria and toxins. TB kills more than three million people each year.

Airlines have reduced the amount of fresh air circulating in the cabin to cut fuel costs. On aircraft built since the 1980s, air is circulated only about every seven minutes compared with every three on older aircraft. The ratio of fresh air to recycled air has been reduced to about 50/50.

The air in cabins either comes directly from outside, through ducts on the side of the plane, or is sucked in through the engines and cooled down.

Edward Kennedy is trying to pass a bill aimed at tightening up standards for the quality of air on planes. But Dr Andrew Horne, a medical officer with the Federal Aviation Administration, says the air quality on planes is 'better, or as good as indoor air quality anywhere else we have studied'.