NEW YORK (AP) — For James Zadroga, dying was as simple as breathing.The highly decorated New York police detective was heading home from work on September 11, 2001, when the mind-numbing news came across his car radio: A plane had flown into the World Trade Center. He rushed back to lower Manhattan, where the twin 110-story towers had collapsed into a toxic pile of burning rubble.

Zadroga spent 470 hours sifting through the smouldering ruins.

Inhale, exhale.

Twelve-hour shifts, nearly 40 of them.

Inhale, exhale.

More than 28,000 minutes, his only protection a thin paper face mask.

Zadroga barely avoided death when 7 World Trade Center tumbled down around him hours after the planes hit. The escape was temporary: By the time he was finished at ground zero, Zadroga was as much a September 11 victim as anyone lost in the tower stairwells — although his suffering was time-released.

His breathing became laboured within weeks, his health deteriorated over months, he was on disability in just over three years. On January 5, 2006, the 34-year-old Zadroga finally succumbed, betrayed by his failing body; the World Trade Center had claimed its latest fatality.

Exhale, one last time.

Two years earlier, his wife died of a heart ailment that family members blame on stress created by Zadroga's fatal illness and his battle with New York City bureaucrats over its cause. Their 4-year-old daughter, born shortly after her father finished work at ground zero, is the newest trade center orphan.

In the days before Zadroga's final breath, his little girl came out of her father's bedroom and spoke to her grandfather.

"I knew my daddy was really sick," Tylerann Zadroga told him. "But I didn't think he'd die this fast."Zadroga grew up in North Arlington, New Jersey, where his dad was chief of police in a blue-collar suburb of 15,000 residents. The youngest of two sons, he was a nonsmoker and a bodybuilder with a rock-solid physique."I used to punch him in the arm, just playing around," recalled his father, Joseph. "By the time he was 16, it started to hurt my hand."

Zadroga graduated from high school, went to a local community college, and then surprised his father by entering law enforcement. The son swapped his small town for the big city: He joined the New York police in 1991, and was soon working the streets of Greenwich Village.

"The apple didn't fall far from the tree," said Monsignor William Fadrowski, a family friend for nearly two decades. "Just like his father, he was a real genuine guy ... just a fine man."

A 1994 New York Times article detailed his work busting beer-drinking teens as part of the city's "quality of life" crackdown, but Zadroga was destined for bigger things.

The hardworking cop became a detective, earning 31 medals for excellence and seven others for meritorious duty during a decade on the job. He married wife Ronda in 2000, and they moved into their own suburban home two hours north of the city.

On the morning of September 11, Zadroga was working in the elite Manhattan South homicide unit — "a pretty prestigious post," said Michael Palladino, head of the Detectives Endowment Association. "To be in that unit after 10 years, that's a testament to his work ethic."

Zadroga was driving home after finishing an overnight tour when he heard about the airplane striking the trade centre's north tower. He reversed course, heading toward the billowing smoke that marked the worst terrorist attack ever on US soil.

Zadroga was soon running for his life when 7 World Trade Center collapsed as he worked nearby. He spent the next month digging through the pile of concrete and chemicals and human remains — even as his pregnant wife stayed alone at home carrying their first child.

"The first weeks were the worst," said Rev. Brian Jordan, a Franciscan priest who met Zadroga at ground zero in the days after 9/11. "We're weren't sure what was going on. The fires were still burning."

The priest remembered Zadroga as conscientious, hardworking and determined to rescue his missing brothers. Day after day, often with just two hours of fitful sleep, Zadroga worked as all hope disappeared and the staggering death toll climbed: 23 fellow NYPD members, 37 Port Authority police, 343 New York firefighters, 2,749 people in all.

"Reality set in," said Jordan. "We were not going to find anybody alive."

When Zadroga returned to his detective squad in October, his breathing was already impaired. When daughter Tylerann was born weeks later, his condition was worsening. By year's end, he was visiting medical specialists to find out what was wrong while constantly missing work, his father said.

There were few answers. And Zadroga's failing health was creating more questions: What exactly was wrong? Was there a cure? What would his family do for money now that his overtime was gone?

With September 11, 2002, approaching, Zadroga was plagued by a constant cough, a sore throat and an ongoing fight with the NYPD over the cause of his sickness. His father-in-law, a Florida clergyman, asked Zadroga to write down his feelings about the past year, hoping to share them with the local congregation.

"They remember the dead," Zadroga wrote of the NYPD, "but don't want to acknowledge the sick who are living. ... I can't pay my bills and work doesn't want to acknowledge that I'm sick, depressed and disgusted."

Zadroga's eyesight began failing, perhaps from trade center materials embedded in his eyes, his father said. By the second anniversary, the trade center rattle in his lungs had Zadroga attached to an oxygen tank.

His wife, dealing with a new baby and a chronically sick husband, fell ill with what family members insist was a stress-related heart problem. The Zadrogas moved to Florida, where they found good weather but no good news: Ronda, just 29, died there two years ago.

Zadroga came back north with his daughter, moved back in with his parents. The NYPD, more than three years after 9/11, finally agreed that he was suffering from pulmonary disease related to his rescue efforts. Union head Palladino said the detective had fiberglass in his lungs, and traces of mercury on his brain.

At age 33, the once-proud detective was receiving a disability pension.

In the Jersey shore home where Zadroga now lived with his parents, two things were happening: Tylerann helped tend to her dying father. And her dying father helped prepare Tylerann for the inevitable.

"It was hard," said Joseph Zadroga. "But she knew. She knew.

James Zadroga died at his parents' home on January 5. Although autopsy results were pending on the exact cause, union officials said he was the first city police officer whose death was linked to working at ground zero. The NYPD confirmed he was the only officer to die after reporting 9/11-related health problems.His father was approached repeatedly at the wake by co-workers and friends from the NYPD. The ex-police chief heard story after story, most of them new to his ears, about his son's exploits in the city.

"He wasn't the type to brag," the father said of the son. There were tears of sadness, and hugs of appreciation.

On the day of Zadroga's funeral, Tylerann sat on her grandfather's lap inside Queen of Peace Church in North Arlington. Nearly 500 people had filled the church to bid farewell to James Zadroga in his old hometown.

The grandparents had told the girl that her father had died a hero — and he was reunited with her mother, Ronda. Tylerann, who now lives with her grandparents, seemed to understand more than most.

"She thinks her dad and mom are stars in heaven," said her grandfather, Joseph, on the day of the funeral. "And she gets mad when there are no stars out."