A new study has found higher levels of cardiovascular disease among 9/11 first responders, and higher rates associated with spending more time at Ground Zero. The study, published this month in JAMA (the peer-reviewed Journal of the American Medical Association), examined the health of nearly 9,800 New York City firefighters who first arrived at the World Trade Center site in the two weeks after 9/11. The study looked at their health between Sept. 11, 2001 and Dec. 31, 2017. More.