According to the man's family, he was exposed to an unknown amount of methane gas.
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The Seymour Johnson Air Force Base confirmed James Grotjan died on Thursday at a hospital in Germany.
Army officials said he died from a non-combat related incident.
Grotjan's family wrote on a Facebook donation page that he was exposed to a methane gas leak July 8 while working underground in a manhole.
As he was trying to climb out of the manhole, he went unconscious and fell back down, according to the family.
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Grotjan was deployed supporting Operation Inherent Resolve, whose mission is to defeat ISIS in designated areas of Iraq and Syria.
"This was a tragic event and our thoughts are with the family, friends and teammates of James," said Col. Donn Yates, 4th Fighter Wing commander. "He was an integral part of our team and our hearts are heavy with his loss."
Nearly $25,000 has been raised for the family on the Facebook donation page.