Ray Pfeifer, 59, died from World Trade Center related cancer on Sunday, officials said. View Full Caption FDNY

FINANCIAL DISTRICT — An FDNY 9/11 first responder who advocated tirelessly for better health care for those exposed to toxic dust clouds at Ground Zero following the terrorist attacks, even as he battled cancer himself, has died, officials said.

Ray Pfeifer, 59, who was awarded a key to the city in 2016 for years of advocacy in Washington to convince Congress to pass the Zadroga Act, which extended health care coverage to around 72,000 who suffered from health issues including asthma and cancer, lost his eight year battle with cancer, fire officials said.

Pfeifer joined the FDNY in 1987, and as a firefighter on September 11, 2001, he slept on his truck for a week following the attacks picking through rubble to find survivors, according to Mayor Bill de Blasio in 2016 speech.

"For a week after that horrible day, Ray slept on his fire truck. He was on Ground Zero for the next eight months scouring the debris," de Blasio said, in a January 2016 ceremony he handed a key to the city to Pfeifer. "People asked him why he stayed. His answer was painful but simple — to find his friends. And that determination, that single-mindedness, that was inspiring."

After his dedication at Ground Zero to finding survivors, Pfeifer used the same diligence to press Congress to take care of those suffering from health conditions related to the World Trade Center attacks, the mayor said.

"There is a famous saying about Ray, that he walked 140 miles through the halls of Congress — that’s how relentless he was. It didn’t matter if he was in pain, it didn’t matter if it was a difficult task, it was something he felt he had to do for an entire generation of first responders and survivors," de Blasio said.

Elected officials across the city and state took to Twitter to remember Pfeifer's hard work.

"Ray Pfeifer was a true fighter and the entire FDNY family deeply mourns his loss." -Comm Daniel A. Nigro. Read more https://t.co/5A95xTwJ64 pic.twitter.com/S7FMAgypPC — FDNY (@FDNY) May 28, 2017

My heart goes out to the family, friends, and colleagues (at Engine 40) of FDNY's Ray Pfeifer, who lost his battle with 9/11 cancer today. — Gale A. Brewer (@galeabrewer) May 28, 2017

Just learned that Ray Pfeifer has died. You meet very few truly great men in your life. Ray was one of them. — Chuck Schumer (@SenSchumer) May 28, 2017

The East Meadow Fire Department, near where Pfeifer lived and where he was a volunteer firefighter, will hold a wake and memorial service on Thursday from 1 to 9 p.m., workers there confirmed. The station is located at 197 East Meadow Ave.

As of Monday the FDNY hadn't made official arraignments for Pfeifer's memorial.