Steve Buscemi is opening up about the post-traumatic stress disorder he experienced from a volunteering stint after the 9/11 terrorist attacks.

Buscemi has been around the New York City block. From standup comedy, independent film, theatre and even firefighting. Now, the “Reservoir Dogs” actor is working to keep attention on the continuing health needs of firefighters as a documentary producer for “Dust: The Lingering Legacy of 9/11”.

The 63-year-old was a firefighter in New York before becoming a world-renowned actor, and was at the aftermath of the devastating 2001 attack helping to search for survivors.

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“I walked around for hours and then found my company, found Engine 55, working there,” Buscemi shared on Mark Maron’s “WTF podcast”, “I asked if I could join them. I could tell they were a little suspicious at first, but I worked with them that day.”

After days of searching through the rubble for bodies, he recalls the moment he realised a friend of his was nowhere to be found.

”I kept calling the firehouse, and of course there was no answer. Because I knew that they would be there [at Ground Zero]. Then I eventually learned that five of [the members of his firehouse] were missing. One of them was a good friend of mine I used to work with.”

Buscemi said he hasn’t “experienced any health issues” as a result, but some Ground Zero first responders have debilitating chronic conditions.

“I was only there for like five days, but when I stopped going and tried to just live my life again, it was really, really hard,” he said. “I was depressed. I was anxious. I couldn’t make a simple decision. All those things.”

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In fact, “It’s still with me,” he said. “There are times when I talk about 9/11 and I’m right back there. I start to get choked up and I realize, ‘Ah, this is still a big part of me.'”

The “Fargo” actor is executive producer of the new documentary “Dust: The Lingering Legacy of 9/11”, which highlights health problems that firefighters who were at Ground Zero have faced. The film aims to help engage Congress to pass legislation to compensate those affected.

“Never forget, because people are still struggling. People are still dying,” he concluded.