The risk of tuberculosis infection on a commercial aircraft.

The cabin of a commercial aircraft is a high density environment in which occupants are potentially at risk of airborne transmission of Mycobacterium tuberculosis. Trans-continental and trans-oceanic flights are routinely undertaken with hundreds of passengers. During these long flights there is an increased duration of potential exposure to airborne contaminants and bioeffluents. This paper determines a "worst case" risk of tuberculosis infection for the passengers and flight attendants based upon typical design and ventilation parameters of a commercial aircraft. The model demonstrates that the "worst case" risk for a general passenger is is 71.8/100000 for a ten hour flight. The risk for flight attendants over a year of occupational exposure is orders of magnitude .greater. The concentration of micro droplet nuclei can be minimized by increasing the ventilation rates. The use of HEPA filtration by the aircraft manufactures reduces the risk by a factor of 2. Increasing the fraction of outdoor air above the present design level of 50% would not result in significant additional risk reduction