In the age of globalization, disease spreads about as quickly as commerce, news and ideas do. Take, for instance, the 2003 SARS outbreak. It quickly dispersed from Hong Kong to 37 countries (killing nearly 1,000 people), and this happened, in part, because of airplane travel.
We now know that airports are key nodes in the spread of global pandemics, although all airports obviously don’t influence this process in the same way. You might assume that the busiest airport hubs would create the biggest ripple effect in exposing a global population to a local outbreak. But new research published in the journal PLoS ONE suggests the network of how and where people travel through airports (taking contagion with them) is much more complicated.
Researchers at MIT have ranked the 37 largest airports in the U.S. on how likely they are to influence the spread of disease in the first few days of an epidemic. The top two contagious airports aren’t surprising: New York’s JFK and Los Angeles International Airport. But very closely behind them, third in the ranking, is the much smaller destination of Honolulu, which gets only 30 percent of the air traffic that JFK does.
According to the researchers’ model, the Honolulu airport could play a central role in a global epidemic because it has several important characteristics beyond sheer flight volume. Flights in and out of Honolulu are dominated by long-range travel. The airport is well connected to several of the much larger hubs, such as LAX, multiplying its contagious effect as sick passengers deboard their flights and make connections to the rest of the world. Honolulu is also geographically positioned such that traffic in and out of the airport comes equally from Asia and the West.
To illustrate their point, the researchers put together this fascinating (and somewhat terrifying) visualization:
These researchers are borrowing from our understanding of all kinds of other complex networks (how fluid flows through subsurface rock, how information flows through social networks, etc.). And their model acknowledges, particularly in the crucial early days of a potential epidemic, that what really matters is not just the size of an airport, but its role in our international transportation network. Atlanta, the busiest airport in the country, is in fact not the most influential when it comes to spreading disease. Surprisingly, it falls to No. 8.
The ranking of these 37 airports, below, could help inform how we diffuse vaccines and other resources to combat the spread of the next SARS. Or, in a less academic sense, it could also inform the many terrible possibilities you want to worry about the next time you’re flying through JFK.
- John F. Kennedy International Airport (JFK), New York
- Los Angeles International (LAX)
- Honolulu International Airport (HNL)
- San Francisco International Airport (SFO)
- Newark Liberty International Airport (EWR)
- O’Hare International Airport (ORD), Chicago
- Dulles International Airport (IAD), Washington, D.C.
- Hartsfield-Jackson Atlanta International Airport (ATL)
- Miami International Airport (MIA)
- Dallas/Fort Worth International Airport (DFW)
- Detroit Metro Airport (DTW)
- Phoenix Sky Harbor International Airport (PHX)
- George Bush Intercontinental Airport (IAH), Houston
- Seattle-Tacoma International Airport (SEA)
- Logan Airport (BOS), Boston
- Philadelphia International Airport (PHL)
- Minneapolis-St. Paul International Airport (MSP)
- McCarran International Airport (LAS), Las Vegas
- Portland International Airport (PDX)
- Salt Lake City International Airport (SLC)
- Ted Stevens Anchorage International Airport (ANC)
- San Diego International Airport (SAN)
- Baltimore Washington International Airport (BWI)
- Charlotte Douglas International Airport (CLT)
- Pittsburgh International Airport (PIT)
- Cleveland Hopkins International Airport (CLE)
- Sacramento International Airport (SMF)
- Tucson International Airport (TUS)
- Indianapolis International Airport (IND)
- Reagan National Airport (DCA), Washington, D.C.
- Burlington International Airport (BTV)
- Louis Armstrong New Orleans International Airport (MSY)
- Nashville International Airport (BNA)
- Memphis International Airport (MEM)
- Kansas City International Airport (MCI)
- Fairbanks International Airport (FAI)
- Louisville International Airport (SDF)
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