Less than a week before the anniversary of the Sept. 11, 2001, terrorist attacks, Mount Sinai Medical Center issued the results of the largest study on related health effects.

It found, among other things, that the ailments tended to be worst among those who arrived first at the site, and that high rates of lung "abnormalities" continued years later.

The study focused mostly on what has been dubbed "World Trade Center cough," which was little understood immediately after the attacks but became a chief concern of health experts and advocates.

Findings highlighted by the study include:

- Almost 70 percent of World Trade Center responders had new or worsened lung symptoms after the attacks.

- Among responders who had no health symptoms before the attacks, 61 percent developed lung symptoms while working on the toxic pile.

- One-third of those tested had abnormal lung function tests.

In lung function tests, responders had abnormalities at a rate double that expected in the general population. Those abnormalities persisted for months and in some cases years after the exposure, the study found.

The findings are based on medical exams conducted between July 2002 and April 2004 on 9,500 ground zero workers, including construction workers, law enforcers, firefighters, transit workers, volunteers and others.

The hospital has been the focal point of New York research on Sept. 11-related illnesses, and thousands have sought treatment there.

The report comes as public concern over the fate of ground zero workers has risen. In a class action lawsuit against the city and its contractors, 8,000 workers and civilians blame Sept. 11 for sinusitis, cancers and other ailments they developed after the attacks.

Dr. John Howard, who was appointed by the Bush administration in February to coordinate the various ground zero health programs, told The New York Times for Tuesday editions that he understands the skepticism of many responders.

"I can understand the frustration and the anger, and most importantly, the concern about their future," said Howard, the head of the National Institute for Occupational Safety and Health. "I can't blame them for thinking, 'Where were you when we needed you?"'

Mayor Michael Bloomberg was expected to announce related program plans on Tuesday.

The programs would "build on our track record of supporting those who supported us in the months after 9/11," he wrote in an op-ed piece in the Daily News. "The city will continue to do everything possible to learn about the problems people face and develop effective strategies to deal with them."

Gov. George Pataki signed legislation last month that expanded benefits for workers who became sick after toiling at ground zero, but Bloomberg objected to the laws, saying they were unfunded and would cost the city hundreds of millions of dollars.

A House committee plans to hold a hearing on Sept. 11 health issues this week.

The city-run World Trade Center Health Registry is tracking the long-term effects on 71,000 people, including those who lived or worked in lower Manhattan at the time of the attacks and the months of cleanup.

Just last week, New York City health officials issued long-awaited guidelines to help doctors detect and treat Sept. 11-related illnesses - medical advice considered crucial for hundreds of ground zero workers now scattered across the United States.