John F. Kennedy airport is No. 1 — but not in a good way. A new study by Massachusetts Institute of Technology lists JFK as the most likely airport in the nation when it comes to spreading extremely contagious diseases like SARS or the H1N1 flu virus.

The study, released today by MIT’s Civil and Environmental Engineering Department, looked at how likely the 40 largest U.S. airports are to spread a contagious disease. Surprisingly, airports that handled the most daily flights did not fall highest on the list.

While Hartsfield-Jackson International Airport in Atlanta has the highest frequency of flights, JFK still tops the list in terms of risky disease-spreading factors. JFK is a high risk due to its connectivity to other airports worldwide, and its location in a large metropolitan area, the report found.

Honolulu International Airport in Hawaii is comparatively tiny, handling about a third as much traffic as JFK, but the airport still ranked third on MIT’s list for disease-spreading capabilities. That’s because of its connections to other large, well-connected cities, according to the report.

In addition to air and people traffic that flow through flying hubs each day, researchers also looked at geographical location and connectivity to determine how fast a disease originating in each airport’s home city would spread over a period of 15 days.

MIT energy studies professor Ruben Juanes said the results could have implications for combating public health crises such as the 2009 H1N1 flu pandemic and the 2003 SARS outbreak.