Refuting claims that aircrafts provide the perfect environment for spreading disease, new study has revealed that flying may be safer than believed.
The researchers from the University of Massachusetts Amherst measured the concentrations of bacteria in the cabin air of 12 commercial passenger aircraft.
"In general, bacterial concentrations and types found during the study should not pose a risk to travellers," said Christine Rogers, a professor of public health at UMass Amherst.
"While we did find elevated levels of bacteria at several intervals during the flight, they were common residents of human skin and mucus membranes, dust and outdoor air, including Pseudomonas, Bacillus and Staphylococcus," she added.
However it is only passengers infected with diseases such as tuberculosis that are a special case that could pose a risk to fellow travellers.
The study led by Lauralynn Taylor McKernan of the National Institute for Occupational Safety and Health examined the sampled cabin air on 12 randomly selected flights using Boeing 767 aircraft, with flight times lasting from 4.5 to 6.5 hours.
Samples were taken in the front and rear of the coach-class cabin at six times during the flight, including boarding, mid-climb, early cruise, mid-cruise, late cruise and deplaning.
Additional air samples were taken from the outside and inside of airline terminals at the cities of departure and landing. Flights were sampled during the summer to eliminate the effect of seasonality.
The highest concentrations of bacteria were measured during boarding and deplaning.
"Concentrations of bacteria were higher in the front of the plane during boarding, which makes sense since the planes were boarded back to front, with standing lines common at the front of the plane," said Rogers.
"This pattern shifted during the flight, with slightly higher bacterial concentrations in the rear of the plane. This could be the result of passengers shedding bacteria as they moved to the restrooms in the back," she added.
The bacteria levels were then compared a study by the U.S. Environmental Protection Agency documenting bacteria in the air of indoor offices and other non-manufacturing workplaces.
Concentrations of total bacteria were higher in the aircraft during boarding, cruise and deplaning, probably due to the number of occupants in a given space and higher levels of human activity.
"Workers and passengers in commercial airliners are exposed to higher levels of common bacteria than people in office buildings," says Rogers. "This points to the need for additional research to evaluate disease transmission on commercial aircraft," she said.
The study appears in the March 2008 issue of the Annals of Industrial Hygiene.