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SYDNEY: The widely-held belief that passengers crowded aboard
airliners are exposed to a high risk of catching infectious diseases
is exaggerated, an Australian government study has found.
The belief that the air in planes is full of
contaminants is based on the perception that it is continually
recycled with limited input from outside, the Australian Transport
Safety Bureau said in a report released Tuesday.
But if recirculation and filtration systems are
working properly, the risk from flying, as far as bugs are concerned
at least, should be no worse than traveling by bus or eating in a
restaurant, the study suggests.
“The risk of transmission of infection on
board an aircraft is probably no greater than, and perhaps less
than, other environments where large numbers of people are gathered
together,” it says.
The bureau noted that the emergence of severe
acute respiratory syndrome (SARS) in 2002 and recent outbreaks of
bird flu in Asia had increased concerns about the risks of air
travel.
Infectious diseases reported to have been
transmitted on board an aircraft include influenza, tuberculosis and
SARS, it said.
But considering the number of flights each day,
such cases occurred relatively infrequently.
There was also evidence that most of the victims
had been infected by such diseases due to sitting close to a sick
passenger and being exposed to droplets from sneezing or coughing
rather than from contaminated recirculated air, the study found.
Outside air entering an aircraft cabin at
altitude is essentially sterile and the airflow pattern and frequent
air exchanges minimize the spread of infections, the report said.
In modern aircraft, the airflow is from the top
of the cabin down to the floor, where it is vented and either
exhausted or recirculated.
“The ventilation system is usually designed so
that air entering the cabin at a given seat row is exhausted at the
same seat row. This limits the amount of air flowing towards the
front and back of the aircraft,” the bureau said.
-- AFP
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