January 18, 2006 -- James Zadroga spent 16 hours a day toiling in the World Trade Center ruins for a month, breathing in debris-choked air. Timothy Keller said he coughed up bits of gravel from his lungs after the towers fell on Sept. 11, 2001. Felix Hernandez spent days at the site helping to search for victims.

All three men died in the past seven months of what their families and colleagues say were persistent respiratory illnesses directly caused by their work at ground zero.

While thousands of people who either worked at or lived near the site have reported ailments such as "trade center cough" since the terrorist attacks, some say that only now are the consequences of working at the site becoming heartbreakingly clear.

"I'm very fearful," said Donald Faeth, an emergency medical technician and officer in a union with two of the ground zero workers who died last year. "I think that there are several people who died that day and didn't realize that they died that day."

Some officials say it is too early to draw that conclusion. Doctors running different health screening programs say it will take decades to get a clear picture of the long-term health effects of working at ground zero.

The city Department of Health and Mental Hygiene, which is tracking the health of 71,000 people exposed to Sept. 11 dust and debris, said last week that it is too soon to say whether any deaths or illnesses among its enrolled members are linked to trade center exposure.

But Robin Herbert, who directs a medical-monitoring program at Mount Sinai Medical Center for more than 14,000 ground zero workers, said "certainly it is not inconceivable" that a person could die of respiratory disease related to Sept. 11.

Karin DeShore said she does not need scientists to tell her what caused the death of her friend Keller, 41. DeShore was a Fire Department captain who took Keller to the trade center on Sept. 11, and barely escaped the south tower's collapse.

"He came back coughing" two days later, she said. Faeth said that Keller told him that he coughed up debris so violently he could barely breathe on Sept. 11, and later developed emphysema.

Keller went home to Levittown on medical leave in March. He died on June 23 of heart disease complicated by bronchitis and emphysema, the Nassau County medical examiner's office said.

Felix Hernandez, 31, worked on rescue and recovery work at ground zero following the attacks, said his former supervisor, Lt. Regina Pellegrino. In 2002, "it started with a cold he couldn't shake ... and it kept getting worse and worse and worse," she said.

Hernandez was diagnosed with various respiratory diseases and was told by doctors at one point that he may have cystic fibrosis, Pellegrino said. He left the job in 2004 when he became too weak to climb stairs, and died Oct. 23 of respiratory ailments in Florida, said colleagues who spoke with his family.

Both Keller and Hernandez, each with a decade on the job, were nonsmokers and had no previous health problems before Sept. 11, Faeth said.

Zadroga, a 34-year-old New York detective, logged 470 hours at the site in 2001, including Sept. 11, and died Jan. 5. Family members and co-workers said he had contracted black lung disease and had high levels of mercury in his brain. Autopsy results have not been released.

David Worby, an attorney representing more than 5,000 plaintiffs suing those who supervised the cleanup over their illnesses, said 21 of his clients have died of Sept. 11-related diseases since mid-2004. He said he was not authorized to release their names, but represented people who toiled at ground zero, at the Fresh Kills landfill in Staten Island where trade center debris was moved, and at the city morgue.

"This is just the tip of the iceberg," Worby said. "Many, many more people are going to die from the aftermath of the toxicity."

Rep. Jerrold Nadler, whose congressional district includes the trade center site, blames some of the illnesses on the failure to provide some workers with proper masks or respiratory protection. A Centers for Disease Control and Prevention study found in 2004 that one in five workers wore respirators while they worked at the site to block out dust laced with asbestos, glass fibers, pulverized cement and other substances.

"All the people exposed should be monitored for life so that we know what happened," Nadler said.

Sept. 11 Toxic Heart Shock

By Susan Edelman & Heather Gilmore, New York Post - Online Edition

February 19, 2006 -- Doctors tracking 9/11 rescue and recovery workers are studying whether the toxic air at the World Trade Center caused not only lung disease and possibly cancer - but also heart attacks, The Post has learned.

The death toll of the Ground Zero heroes - firefighters, cops, EMTs, construction workers, immigrant laborers and others - is climbing, and a growing number are dying of heart attacks and cardiovascular disease.

Researchers who have studied Ground Zero air samples - initially called "safe" by the EPA - are not surprised at illnesses surfacing in many who worked without respirators or safety suits at the hugely hazardous site.

"These people have been screwed," said Thomas Cahill, a scientist at the University of California-Davis who has studied the finely pulverized airborne poisons that WTC workers "inhaled deep into the lungs" for months.

"They're as much victims of 9/11 as those killed in the buildings."

Doctors monitoring 13,000 WTC workers are investigating a possible link between the heart problems and the respiratory ailments so common among the tens of thousands of Ground Zero workers and nearby residents.

"There is an increased risk of heart problems from lung disease," said Dr. Stephen Levin, of the WTC medical monitoring program at Mount Sinai School of Medicine in Manhattan.

"There is also evidence that people exposed to micro-fine particles -which was certainly the case at the World Trade Center - are at increased risk for heart disease."

Researchers will soon consult top cardiologists on possible blood tests to detect the hidden danger, Levin told The Post.

The new focus comes two weeks after James Doyle, 54, a retired transit worker from Staten Island, died of a heart attack.

Active and athletic before 9/11, Doyle developed lung disease after weeks of digging at Ground Zero and had to use an oxygen pump.

Last month, Kevin Lee, 31, a seemingly healthy NYPD cop, collapsed and died while chasing a suspect, raising questions about the effects of his many hours at Ground Zero.

And last June, Tim Keller, 41, an FDNY emergency medical technician and father of four, died of a heart attack after going on disability for post-9/11 asthma, bronchitis and pulmonary emphysema.

"By the end, he couldn't walk two steps without taking a breath," said his son David, 19.

"One day, he just went - his lungs stopped pumping enough blood into his heart."

Doctors told the family Keller's death was "directly related to his days of search and rescue down at Ground Zero," the son said.

David Worby, a lawyer representing 6,000 WTC workers in a class-action lawsuit, said about six men in their 30s or 40s with no family history of coronary disease have died of heart attacks so far.

"Hundreds more will die prematurely," he predicted. "This is scratching the surface of all the diseases linked to these toxic exposures that people must be tested for and treated."

So far, at least 24 of the 6,000 workers have died from inhaling, ingesting or absorbing WTC dust and fumes - rife with thousands of pounds of pulverized mercury, lead, asbestos, dioxin, benzene, cadmium and PCBs, the suit argues.

The dead include men in their 30s, 40s and 50s from cancers of the esophagus, throat, pancreas, and kidney, Worby said.

Such cancers normally take years longer to develop, but Worby contends they struck sooner because of a "synergistic effect" of the deadly toxins - a theory Levin said is under study.

Others have died or suffer from lymphoma and leukemia - blood cancers that can develop several years after exposure to toxins.

After working 12-hour days for three months, digging for body parts and doing security at Ground Zero, NYPD detective Ernie Vallebuona, 40, is fighting lymphoma.

Since a recurrence, he has undergone a second round of chemotherapy and blood stem-cell transplants - and will learn this week whether it worked.

Weakness and fatigue after 9/11 - "I couldn't pull my kids in a wagon to the beach" - led doctors to discover a large mass in his abdomen.

The disabled vice cop, bald from the treatment and on many medications, is so vulnerable to deadly infection he can't eat out or play with his two sons.

He couldn't root for them at the recent Boy Scout Pinewood Derby because of the crowd.

"It breaks my heart," Vallebuona said. "I'm just holed up in the house. I feel like such a lump."

Fellow detective Rich Volpe, 38, "spit up blood and black stuff from my lungs for months" during 12-hour shifts at Ground Zero and the Fresh Kills landfill.

Volpe was diagnosed with kidney disease in 2002, and has lost 50 percent of function in both kidneys.

He will eventually need a transplant to survive. Doctors have told the bachelor he may never have kids.

Speaking between loud gasps and coughs, ironworker John Sferazo, 50, recalled inhaling "green gases" bubbling up from Ground Zero for 30 days after the terror attacks.

"There were times I couldn't wear any type of respiratory protection because the air was so bad you had to inhale whatever you could to try and pull some oxygen out of it," he said

Sferazo, a father of three, has lost a third of his lung capacity. Last week he attended the funeral of a fellow Local 361 worker and Ground Zero partner, Michael Kendrick, who died of lung cancer.

"I saw his daughter kiss his corpse goodbye. It was tragic," he said.

While "cancer is a continuing concern," among firefighters, cancer and heart attacks have not risen above normal since the terror attacks, said Dr. Kerry Kelly, the FDNY's chief medical officer. She did not give numbers.

But more than 2,000 Bravest have suffered pulmonary problems, including 500 forced to retire on disability, she said.