When evaluating the children, Kavanaugh and Ruee Huang, the pediatrician, ask about the impact of 9/11 on the entire family. The child may have been far from Downtown on 9/11, but if a parent suffered serious physical or mental effects, that can affect the child, Kavanaugh said.

Dr. Huang said she has even seen physical effects of 9/11 on children who were nowhere near the dust cloud. If one of their parents was working Downtown on 9/11 or worked in the cleanup and recovery effort, the dust could have traveled back to the child's apartment on the parent's clothes.

At the heart of Kavanaugh and Huang's task is to decide whether a child's illness is connected to 9/11.

"It's really difficult," Huang said during a recent interview at the center. "We don't know for certain what is World Trade Center-related."

Illnesses like asthma can take years to show up, and it can be tricky to pinpoint the origin of anxiety or mood disorders.

Kavanaugh takes a meticulous clinical history of the children, trying to document how they functioned before and after 9/11.

"Often there is a great deal of agreement between the family and us," Kavanaugh said. That's the advantage of doing a comprehensive assessment, she added: "An answer emerges that makes sense to everyone who knows the child."

When Kavanaugh and Huang uncover symptoms that they believe are not related to 9/11, they refer the family to another doctor or program within Bellevue. Since Bellevue is a public hospital, everyone receives treatment regardless of ability to pay.

The pediatric program opened at the end of last year, but few children have enrolled so far. The good news is that appointments are available almost immediately. The bad news is that the doctors need to see patients so they can learn more about the illnesses affecting children and how to combat them.

Miles is spreading word of the program through community groups, but one obstacle he hits is Bellevue's history as a public hospital.

"There are misconceptions about a public hospital," Miles said. "But we have the most highly trained clinical staff anywhere."

Kimberly Flynn, who sits on the Environmental Health Center's community advisory group, encourages parents to bring their children to the pediatric program even if the children are already getting good care elsewhere.

"If any new problem emerges among children exposed to 9/11 dust and smoke, Bellevue doctors will be the first to know and the first to figure out how to treat it," Flynn said. "They know more and will continue to learn more about W.T.C. illness in children than any other practitioners."

The Bellevue program is not designed to replace children's regular pediatricians, but rather to add 9/11-related expertise to the care children are already receiving, she said. The doctors at Bellevue work with children's pediatricians to coordinate treatment.

The pediatric program is based on the W.T.C. Environmental Health Center's adult program, which has enrolled 2,700 patients at its three locations: Bellevue, Gouverneur Healthcare Services and Elmhurst Hospital in Queens. The pediatric program is just at Bellevue.

At Bellevue, the Environmental Health Center sits in a sweeping addition, which wraps around the hospital's original façade. The new wing, separated from the rest of the hospital by a sunlit indoor courtyard, houses ambulatory and outpatient care. The pediatric clinic is in the process of moving into the Environmental Health Center's part of the new wing.

The city gave the Environmental Health Center $16 million in 2006. Private philanthropic organizations, including the Red Cross and the 9/11 fund, provided the seed money for the center, but the city first stepped in two years ago with a solid commitment.

Miles appreciates Mayor Michael Bloomberg's support all the more, because the federal government has avoided paying for health treatment for residents, students and office workers ever since 9/11. The U.S. Dept. of Health and Human Services has so far refused to fund the program even though President Bush signed the budget into law authorizing treatment funding for non-responders.

"That our program isn't funded by the federal government is stunning," Miles said. "The city and the mayor stepped up when the federal government did not."