This is absolutely tragic. Retired NYPD Capt. Douglas Greenwood — who was once a 9/11 first responder — took his own life earlier this week after the lung disease he suffered from as a result of serving at Ground Zero in the wake of the horrific terrorist attack became too much to bear. The New York Post reports that he shot himself to death in a park near his home on Long Island. He was 61.

His friend Kevin McCormick told the paper that, sadly, news that Capt. Greenwood took his own life didn’t come as a surprise. “He talked about shooting himself as an inevitable thing. He said, ‘When there’s no more quality of life, I’m going to do it.’ He knew it was coming.”

In the weeks after 9/11, Capt. Greenwood spent 40 consecutive days on “The Pile,” which is what those who worked in the rubble called it. To date, the effects of the “toxic dust” inhaled by the first responders are unknown, though it’s been commonly observed that pulmonary diseases are prevalent among those that worked at Ground Zero. A 2010 study of 5,00 by the chief medical officer for the Office of Medical Affairs at the NYC Fire Department found that all 5,000 workers had impaired lung function, with an average impairment of 10 percent.

The fallen officer’s work in the wake of the attack was significant, friend and retired detective Ralph Friedman revealed. “He was in charge of all the NYPD boots on the ground,” Det. Friedman said. “He’d be commanding the scene, but he also did grunt work — everybody pitched in. Everyone was sifting through he scene for bodies, body parts. He could have stayed in the car. But he was right there. And it cost him his health — as it did for a lot of officers. They did very heroic work — there’s no way around it. And he was right there.”

After retiring from the police force, Capt. Greenwood found a second love — working at NYC’s famed pizzeria Blecker Street Pizza. He didn’t have a wife or any children. His older brother Gregory told the Post, “He was married to the NYPD and pizza.”

If you or someone you know is contemplating suicide, call the National Suicide Prevention Lifeline  at 1-800-273-8255.