World Trade Center Health Program
On September 11, 2001, 19 terrorists associated with the Islamist militant group al-Qaeda hijacked four passenger jets in a series of suicide attacks on the United States, killing 2,996 people and injuring more than 6,000 others. Hijackers flew planes into two main towers of the World Trade Center, resulting in the collapse of three buildings of the World Trade Center complex, and the Pentagon, resulting in the partial destruction of the western side in the building. The resulting dust cloud due to the collapse of the World Trade Center covered Manhattan for days and contained thousands of tons of toxic debris, including asbestos and other known carcinogens. Another hijacked plane crashed into a field in Shanksville, Pennsylvania following an attempt by the passengers to retake control of the plane. No one in the airliners survived.
As of 2011, approximately 18,000 people have received medical treatment for illnesses related to toxic dust from the World Trade Center site. A study of rescue workers released in April 2010 found that all those studied had impaired lung functions, and that 30–40% were reporting little or no improvement in persistent symptoms that started within the first year of the attack. In 2011 a major research study showed significant long term medical and psychological effects among first responders to the World Trade Center site. These effects include elevated levels of asthma, sinusitis, Gastroesophageal reflux disease and posttraumatic stress disorder.
American Airlines Flight 11
The 9/11 Commission estimated that the hijacking began at 08:14, when the pilots stopped responding to requests from the Boston Air Route Traffic Control Center (Boston ARTCC). It is believed that Waleed al-Shehri made the first move. At 08:13:29, as the aircraft was passing over central Massachusetts at , the pilots responded to a request from Boston ARTCC to make a 20-degree turn to the right. At 08:13:47, Boston ARTCC told the pilots to ascend to a cruising altitude of but received no response. It is believed that Captain Ogonowski was stabbed to death in order for the hijacker pilot Mohamed Atta to take control of the plane and crash it into the North Tower of the World Trade Center. Before dying, Ogonowski keyed the cockpit microphone; "pushing its button intermittently to signal that something was wrong and at one point allowing them to hear the voice of the hijacker." At 08:16, the aircraft leveled off at and shortly thereafter deviated from its scheduled path. Boston ARTCC made multiple attempts to talk to Flight 11 without reply, and at 08:21, the flight stopped transmitting its Mode-C transponder signal.