More than 400,000 people were in lower Manhattan the morning of 9/11, including thousands of office workers, small business owners, city employees, visitors and others. They fled at different times after the attacks. Some found their offices and stores buried under dust and debris when they returned. Others worked for months where the dust was less visible. Because of different exposures, it has been more difficult to determine how this group’s health was affected by 9/11.

The World Trade Center (WTC) Health Registry, a database of more than 71,000 people directly exposed to the September 11 attacks offers researchers a resource to track the physical and mental health effects of 9/11. More than 50% of enrollees said they were in a building (including more than 3,700 who worked in the World Trade Center), on the street or on the subway south of Chambers Street on 9/11. Findings based on Registry data collected in late 2003-2004 and 2006-2007 provide more information about the health of enrollees. The Registry is also studying the impact of 9/11 on respiratory health.

In addition, millions of New Yorkers, other Americans and people worldwide who watched constant media coverage of 9/11 were indirectly exposed to the terrorist attacks on the United States.