John Feal was not at the World Trade Centre when the planes struck, but as a demolition supervisor, he was one of an army of construction workers sent to Ground Zero in the aftermath of the September 11, 2001 attacks.
Days after he began working at the site, several tonnes of steel fell on his left foot after part of the structure collapsed. He spent 11 weeks in hospital and half his foot was amputated after he developed gangrene and sepsis.
But he was denied any money from the original compensation fund, which only helped people injured within 96 hours of the attack.
Mr Feal, from Long Island, has since become a prominent voice in the battle to help those who suffered long-term illnesses following the events of 9/11.
More than 2,600 people died at the World Trade Centre on September 11.
First responders rushed to the scene, followed by construction workers including Mr Feal. For days, they sifted carefully through the debris, searching for human remains.
The structure was unstable, as Mr Feal discovered to his cost. Fires burned on the site for months and people working at Ground Zero picked their way through the wreckage, fearful of sustaining injuries from the jagged steel and iron strewn across the area.
Some first responders even wrote their names and phone numbers on their arms in case they were crushed or fell into a crevice.
In the aftermath of the attack, massive dust clouds rose from the site, enveloping the area in a dark gloom.
The wind carried a lethal cocktail of carcinogens including benzene, dioxins and asbestos that hung over Lower Manhattan for months.
Some 400,000 people were exposed to toxic dust from the collapsed twin towers, sustained physical injuries at the site or suffered emotional damage, official estimates show.
Only last year, a study by the Icahn School of Medicine at Mount Sinai in New York City found that first responders were twice as likely to have contracted thyroid cancer than the general population.
Their risk of leukaemia was 41 per cent higher and the rate of prostate cancer was 25 per cent above average.
There were also long-term victims at the Pentagon and in Shanksville, Pennsylvania, where a United Airlines flight crashed after it was hijacked.
Even today, the toll is rising.
At the last count, 255 New York police officers and 253 members of the city’s fire department had died from World Trade Centre-related illnesses.
Many victims were first responders but the toxic fallout from 9/11 also affected people living and working across Lower Manhattan - and Mr Feal took up the cudgels on their behalf.
“I started fighting for myself and then began helping others,” he told The National.
“When I was going to therapy and survivor groups, I saw everybody was going through the same thing that I was.”
Many were suffering from cancer, respiratory sicknesses and chronic obstructive pulmonary disease.
“The treatment was not good. It took us years to get bills passed to make sure they got free health care and compensation. We had to fight every step of the way.”
Mr Feal joined forces with Carolyn Maloney, a New York congresswoman, and her chief of staff, Ben Chavet, in trying to bring justice to thousands of people who, having contracted serious illnesses, were being left to fend for themselves.
Support was at best patchy after the closure of the original Victim Compensation Fund in 2004.
What aid there was — such as the Medical Monitoring and Treatment Programme — was not especially well funded, receiving only $475 million between 2002 and 2011, a fraction of the $7.4 billion allotted to the original Victim Compensation Fund.
In some cases, survivors had to turn to philanthropic organisations for financial support.
Others were dependent on health insurance.
As early as 2005, Ms Maloney introduced the Remember 9/11 Act to provide health care for those who had contracted diseases such as cancer following the attacks.
The bill went nowhere.
Mr Feal threw his weight behind the campaign. Having finally won a settlement on his own behalf, he spent thousands of dollars bringing other ailing survivors to Washington to lobby for legislation.
He threatened to run primary candidates against any New York congressional Democrats if they failed to vote for a bill providing compensation.
Ms Maloney tried again, introducing the James Zadroga 9/11 Health and Compensation Act, named after a police officer and non-smoker who died of respiratory disease.
He was the first New York police officer whose death was attributed to toxins at the World Trade Centre site.
The measure eventually passed in January 2011, albeit with the funding slashed from $7.4bn to $4.6bn, and the 10-year time limit slashed to five because of Republican opposition.
It established the Word Trade Centre Health programme, which covered at least 68 cancers linked to toxins at Ground Zero.
The act, which re-established the Victim Compensation Fund, was supported by Jon Stewart, an American comedian best known as the host of The Daily Show.
He did the same in 2015, when the fund was renewed.
But within three years the Victim Compensation Fund was running out of cash and with the clock running down, pressure mounted for a lasting solution.
A fresh measure, called the Never Forget the Heroes Act, was introduced. Its key provision was to extend the Victim Compensation Act until 2090, again with the support of Mr Stewart.
Appearing before a subcommittee of the House Judiciary Committee in June 2019, he laid into Congress with astonishing ferocity.
“Behind me, a filled room of 9/11 first responders, and in front of me, a nearly empty Congress,” he said.
The bill passed, albeit with two Republican senators — Mike Lee and former presidential candidate Rand Paul — objecting on grounds of cost.
Care is now in place which should at least provide some financial security for those who have paid dearly over the past two decades.
“These responders and survivors should not have had to drag themselves through the halls of Congress to get action but that is what they had to do,” Mr Chevat said.
“After struggling for so many years, those affected by the toxins are now getting the care they deserve and need, and compensation for their injuries.”
Now 54, Mr Feal regards his suffering as minute compared to other victims of the attack. “My story pales into comparison to those who have died.”
But he takes pride in the success of his campaign. “It is the reason why more than 100,000 people got free health care.
“I don’t want to downplay the significance of others. But if we hadn’t done what we did, there would not have been legislation today.”