News

Does the air quality on passenger planes bring you down? A new study suggests that the oils on your skin, hair and clothing may be partly to blame.

A team of U.S. and Danish researchers discovered that elevated ozone levels typically found on some planes can react with natural oils to produce chemical byproducts that can worsen the nasal irritation, headaches and dry eyes associated with air travel.

For the study, the researchers got a group of volunteers to sit in a mockup of an airline cabin and then exposed them to air flow and ozone levels experienced on real flights. About half the irritating chemical byproducts, such as aldehydes, were the direct result of ozone reacting with skin, hair and clothing, according to the findings published in the journal Environmental Sciences & Technology.

Ozone levels can be high inside a plane when the aircraft flies through a part of the upper atmosphere where this highly reactive oxygen molecule accumulates. (The ozone layer plays a very useful role, shielding the Earth from harmful solar rays.)

"Even when a plane recycles air, it still has to bring in air from outside," explained the study's lead researcher, Charles Weschler at the University of Medicine and Dentistry of New Jersey.

"On today's planes, about 50 per cent of the air supplied to passengers has been recirculated and about 50 per cent is fresh air. It is this 'fresh air' that contains ozone from outside the aircraft."

Most wide-bodied planes are equipped with ozone-destroying catalysts in their ventilation systems. But this protective equipment is far less common on narrow-bodied (single-aisle) aircraft, Dr. Weschler said.

So is there anything passengers can do to protect themselves?

"Our skin oils are important for our skin. It would not be a good idea to try to reduce our skin oils before flying," he said in an e-mail interview. "It might help a little bit to wear less perfume or aftershave when flying on a plane with ozone. Some of the scents used in such products react with ozone."

PET KILLER

House pets can suffer from second-hand smoke, too. In recent years, many studies have focused on the dangers of second-hand tobacco smoke to people. But a separate body of research shows that these noxious fumes also pose particular health risks to cats and dogs.

For instance, a study conducted at the Tufts University school of veterinary medicine found a strong link between second-hand smoke and oral cancer in cats.

"One reason cats are so susceptible to second-hand smoke is because of their grooming habits," said Carolynn MacAllister, a veterinarian at Oklahoma State University.

"Cats constantly lick themselves while grooming; therefore they lick up the cancer-causing carcinogens that accumulate on their fur. This grooming behaviour exposes the mucous membrane of their mouth to the cancer-causing carcinogens."

Another study carried out at Colorado State University found an elevated risk of nasal cancer in some breeds of dogs living in homes with smokers.

"The increased incidence was specifically found among the long-nosed breed of dogs," said Dr. MacAllister, who has been reviewing the research. She added that carcinogens tend to build up in the mucous membranes of long-nosed dogs, so not as much reaches the lungs.

That appears to put these dogs at a higher risk of developing nasal cancer. Short- or medium-nosed dogs showed higher risks of lung cancer.

The research, she says, clearly demonstrates that pet owners shouldn't be smoking around Fido or Fluffy. Better still, they should "stop smoking altogether."

ANTIBIOTIC WARNING

An antibiotic sold under the brand name of Ketek should no longer be used to treat bronchitis, sinus infections, tonsillitis or sore throats, according to a statement released by the drug's manufacturer, Sanofi-Aventis.

The controversial drug has been linked to liver damage, fainting spells and impaired vision. Since it was first stocked on Canadian pharmacy shelves in 2003, Health Canada has received more than 100 reports of suspected adverse reactions.

Health Canada decided to restrict use of the drug after reviewing the safety data. But Ketek can still be prescribed to treat a "community-acquired pneumonia," medically known as CAP.

Alastair Sinclair, a Health Canada spokesperson, noted that Ketek is effective against some strains of pneumonia that are resistant to other antibiotics. So, from a risk-benefit assessment, "Ketek continues to be acceptable for the treatment of patients with the more serious condition of community-acquired pneumonia of mild to moderate severity" he said in an e-mail.

Even so, the advisory also warned the antibiotic should not be used by those who have previously suffered from myasthenia gravis (a muscle disorder caused by a nerve defect) or liver-related illnesses such as jaundice and hepatitis.

Ketek has also been under investigation in the United States.

ptaylor@globeandmail.com