NEW YORK -- The death of a 34-year-old police detective who developed respiratory disease after working at ground zero is "directly related" to Sept. 11, 2001, a New Jersey coroner said in the first known ruling positively linking a death to cleanup work at the World Trade Center site.

James Zadroga's family and union released his autopsy results Tuesday, saying they were proof of the first death of a city police officer related to recovery work after the terrorist attacks.

"It is felt with a reasonable degree of medical certainty that the cause of death in this case was directly related to the 9/11 incident," wrote Gerard Breton, a pathologist at the Ocean County (N.J.) medical examiner's office in the Feb. 28 autopsy.

Zadroga, of Little Egg Harbor, N.J., died in January of respiratory failure and had inflammation in his lung tissue due to "a history of exposure to toxic fumes and dust," Breton wrote.

The detective spent 470 hours after the attacks sifting through the twin towers' smoldering ruins, wearing a paper mask for protection. His breathing became labored within weeks, he developed a cough and he had to use an oxygen tank to breathe. He retired on disability in November 2004.

The coroner found material "consistent with dust" in Zadroga's lungs and damage to his liver and said his heart and spleen were enlarged.

Zadroga's parents and 4-year-old daughter appeared at a news conference with half a dozen other detectives who said they have suffered from cancer, strokes, lung disease and other ailments because of post-Sept. 11 work at the trade center site.

A class action lawsuit and families of ground zero workers have alleged more than two dozen deaths are related to exposure to trade center dust, which doctors believe contained a number of toxic chemicals including asbestos and more than 1 million tons of tower debris.

"They all knew it was detrimental to their health," said Joseph Zadroga, James Zadroga's father. "They all knew that, yet they stayed there."

Doctors running health screening programs, including a city registry following tens of thousands of people, say it will take decades to truly assess the health effects of working at the trade center site.

"The World Trade Center Health Registry will help us draw meaningful conclusions about the long-term health effects of the WTC disaster," the city Department of Health and Mental Hygiene said in an e-mailed statement. "While the registry is not designed to track individual diagnoses, staff continue to evaluate the health of the nearly 71,000 residents, children, rescue and recovery workers and volunteers enrolled."