Long-term effects for those who responded to Ground Zero

As the nation mourns the thousands of lives lost in the Sept. 11 attacks, Channel 9 is learning more about the long-term effects on those who responded to Ground Zero.

[RELATED: 9 Investigates: 17 years later, first responders remain impacted by effects of 9/11]

Local Federal Bureau Investigation agents who investigated the attacks told Channel 9's Brittney Johnson that they are worried their work at Ground Zero could still kill them.

Twenty-four hours after Agent John D. Wydra watched planes crash into the World Trade Center and Pentagon, he was on the way to Washington DC to lead a team of FBI agents from Charlotte to collect evidence.

“In our minds the country was at war, we were trying to figure out who did this,” said Wydra.

Wydra and his team spent weeks on their hands and knees sorting through the wreckage.

Photos still hang on his wall showing the massive mounds of toxic debris.

“Every day you were covered in dust,” said the agent. “Every day you would cough up black chunks of dust.”

[RELATED: Cornelius firefighters remember victims, friends killed in 9/11 terror attacks]

Consumed by the real-time race to protect the country, the agents didn't consider that they weren't protecting themselves.

Wydra told Channel 9, “Nobody thought they were going to get sick, not then or later.”

It wasn't until 2008, when Wydra was diagnosed with cancer that they realized just how exposed they were while investigating the attacks.

Out of the 16 men on Wydra’s team, three of them have been diagnosed with cancer.

One member of the team, Agent Jerry Senatore died in 2011 and his photo is displayed on the Wall of Honor at the Charlotte Headquarters.

“I look at it and I can't believe it. We came in the bureau at the same time together,” said Wydra.

Last week, FBI Director Christopher Wray held a press conference shining a light on the ongoing sacrifice of federal agents.

According to the FBI, 31 agents have been diagnosed with cancer related to 9/11 and 15 have died.

Wilmington agent Stanley Meador was diagnosed with colon cancer in 2013.

He survived 24 rounds of chemo and this year on September 11 marks two years without a reoccurrence.

[RELATED: US marks 9/11 with somber tributes, new monument to victims]

“I will tell you the FBI mission is to protect American people and on that day, no different. That's what we do,” said Meador.

Both agents told Johnson that their battle is far from over.

“Every doctor’s appointment I go to, I’m wondering if this is it. If it’s going to come back,” said Wydra.

Despite the agent’s ongoing fear that his cancer will return, when Johnson asked him if he would volunteer all over again, he said “yes, I would do it today.”

The World Trade Center Health Program currently helps agents with healthcare costs.

The FBI Agents Association is fighting to get the Department of Labor to recognize agents' cancer deaths and illnesses as work-related, which would give victims and their families access to full federal benefits.

Read more top trending stories on wsoctv.com: