The novel swine flu is showing the world just how interconnected we are and how commercial aircraft can serve as vehicles of rapid disease spread.

I am frequently asked: What is the risk of catching an illness while flying?

In a nutshell, the risk of getting an infection while you're in an enclosed space such as an airplane depends upon three factors: The infectiousness of the contagious person spreading the illness; the degree of your exposure (how close you are to the contagious person and for how long); and the ventilation of the space or passenger cabin.

We really have no control over the infectiousness of our fellow passengers, and usually, you really don't have much of a choice about your seating partners. So the exposure is pure chance.
 

Read the full commentary from Dr. Gendreau at CNN.com where the piece first appeared.

Mark Gendreau, MD, FACEP, is senior staff physician and vice chairman of emergency medicine at Lahey Clinic, Burlington, Massachusetts, and assistant professor of emergency medicine at Tufts University School of Medicine in Boston. His interests include health issues associated with commercial air travel, including transmission of infectious diseases.