Such veterans can deal with staged shows, like those in city parks and stadiums. But the booms and bangs and flashing light on neighborhood streets, parking lots and fields are another matter, he said.
Those "bring a survival method people use to stay alive," he said. "They're alert to fear or potential threats. They're mobilizing their bodies, getting their adrenalin ready."
Many of those with PTSD try to get out of town to get away from the noise, Allen said.
"One vet went camping in remote areas, then had to find 'remoter' areas because people were finding him," he added.
Paul Hunter, a Vietnam veteran, knows the feeling. A former Marine, he served in 1965 and 1966.
"You get into the combat zone, and you're put on edge every time you hear an explosion of every kind," he said. "It's a sign that something is screwed up. They're attacking you, and you jump … and think, 'Ah, I have to get my rifle.' "
Although Hunter says his symptoms have faded, and that recent veterans are much more susceptible to fireworks, he still gets "a little bit paranoid" about neighborhood celebrations, momentarily believing revelers are messing with him.
Then, he said, he sits down and thinks, "No, they're not. They're just having fun with their kids."
Overall, 2.5 million Americans have served in the two war zones in Iraq and Afghanistan, but the Utah Department of Veterans and Military Affairs has no estimate of how many Utahns are among them.
Allen said roughly 12 percent to 15 percent of all service members have PTSD, although actual percentages are difficult to confirm.
As for late-night fireworks enthusiasts, he said, "Part of it is being thoughtless [and] unaware of the implications, especially for veterans. We say we support veterans. We should say we don't support[neighborhood] fireworks.''