Survivors of the terrorist attacks on New York's World Trade Center, especially the ones who were exposed to dust from the towers' collapse, are suffering worsening respiratory and psychological symptoms. The U.S. Centers for Disease Control and Prevention said in a study that will be monitored for years.

As the buildings fell, about 62 percent of the survivors were enveloped in dust, smoke and debris spewed into the air, and tracking their health could lead to building designs that minimize injury risks, the CDC said.
About 57 percent of the survivors reported new or worsening respiratory problems after the attacks, and 21 percent have had severe headaches, CDC said, citing interviews with 8,418 adults who were in or around the site.

The particles of concrete, glass, plastic and paper were released into the air and fires at the 16-acre pile of rubble burned for about 3 months, and many people inhaled the fumes when they returned to work in lower Manhattan.

The CDC said it will periodically monitor the physical and mental health of 71,437 people affected by the attacks for 20 years as part of its World Trade Center Health Registry program. About 64 percent of the survivors experienced three or more psychologically traumatizing events.