Nearly 1,700 children developed respiratory symptoms after being exposed to toxic dust following the collapse of the World Trade Center, new data shows.

In a survey of 3,100 children enrolled in the World Trade Center Health Registry, 53% reported symptoms such as coughing, wheezing, or shortness of breath in the days and weeks after the attacks of September 11, 2001, the city’s health department reported yesterday.

Children exposed to toxic dust also developed asthma twice as often as the general population, the survey found. In 2003, 21% of children exposed to the dust cloud had asthma, compared with 7% of children with asthma in the Northeast region of the United States.

Among children in Lower Manhattan who were not exposed to the dust cloud, 12% had asthma. In an analysis of the children’s mental health, the data indicates that 3% — or 77 children — showed symptoms that suggested posttraumatic stress.

Health officials said the findings concerning the children’s respiratory symptoms are consistent with data among adults exposed to toxic dust from the World Trade Center.

“Being caught in the dust cloud did seem to elevate the risk,” a deputy health commissioner at the city’s Department of Health and Mental Hygeine, Lorna Thorpe, said. “So it’s not totally surprising, but it is concerning,” she said.

Yesterday, Ms. Thorpe said it was unclear how many children might be affected who did not enroll in the registry.

The department is currently conducting a follow-up survey in order to determine the long-term health impacts of the World Trade Center collapse.