John Marshall is a combat veteran of the first Gulf War, well known in the area as captain of the Duluth Honor Guard, which serves at military funerals.

His patriotism is beyond question, but one aspect of Independence Day is difficult for Marshall.

"The Fourth of July, when you've got the bangs and the smell of gunpowder, it drives me nuts," Marshall said recently. "I don't go watch fireworks just because it causes me that much discomfort."

He's not alone. The National Center for PTSD at the U.S. Department of Veterans Affairs estimates that about 3 out of every 10 Vietnam veterans have suffered from post traumatic stress disorder in their lifetimes. The percentage is smaller, but still significant, for veterans of more recent conflicts in Iraq and Afghanistan.

And if they have PTSD, they probably struggle with regards to fireworks.

"Even back in 2000 when I was working with Vietnam vets, it was one of the questions we used to ask as a way of detecting if someone might have PTSD," said Christopher Erbes, a psychologist with the Minneapolis VA Health Care System. "We'd ask them, 'What do you do on the Fourth of July?' And if people would say, 'Oh I go to the fireworks show.' We're like, 'Huh, this person may not have post traumatic stress.'"

But for those who do have it, the season of bangs and booms and bright flashes can be intensely difficult.

"Some veterans, they'll just kind of hole up in a basement somewhere until all the real intense stuff gets finished," said Chris Roemhildt, veterans outreach specialist for the Duluth Vet Center at 4402 Haines Road. "You feel kind of isolated, especially if the rest of your family is going down to the big show at Bayfront."

Roemhildt had his own struggles with fireworks after serving with the First Armored Division in Iraq in 2003-4 and 2005-6.

"I had a lot of problems with it when I was first adjusting back to civilian life," he said. "The really large, professional fireworks, you can kind of feel the concussion in your chest. So that causes quite the physical and mental reaction. ...

"The ones that were in my neighborhood, the ones that I wasn't expecting, those ones would often catch me off guard, and that's what would create that response."

Concern from veterans with PTSD and their supporters has led to a backlash of sorts, particularly with regards to the neighborhood version of fireworks.

Around this time of year, red, white and blue-themed signs appear at this time of the year with the words "Military veteran lives here; please be courteous with fireworks."

The signs are sponsored by an organization called Military With PTSD with the purpose of bringing awareness of the concern, said Shawn Gourley, its executive director.

"We never wanted to stop fireworks," said Gourley, who lives in Evansville, Ind.

Roemhildt said he has mixed feelings about those signs.

"It depends on the spirit with which we're putting that sign out," he said. "If it's just simply to educate people and let them know, 'Hey, this is something I struggle with,' that's fine. But if you're putting it out there and expecting your neighbors to not enjoy the Fourth of July the way that we have for hundreds of years, I'm not sure if I agree with that."

Erbes agreed that the signs can have value if seen as a conversation-starter.

"I wouldn't necessarily say, 'Well, that means fireworks are forbidden in the neighborhood'," he said. "But it really would be a great opportunity to talk to the veteran and say, 'OK, that's really good to know. We're only going to do fireworks from 7 to 9, and then we're going to completely stop. Is that going to be OK?' If you can just give people that information, I think that helps them."

For veterans with PTSD, avoiding fireworks displays isn't a good long-term strategy, Erbes said. Studies, he said, support "exposure therapy," meaning taking in safe experiences that the brain might initially interpret as dangerous.

"The way that you treat PTSD, in treatment or just kind of in life sometimes, is you get around those things that used to remind you so much of the event," Erbes said. "And the more you get around it, and the more nothing bad happens when you're around those reminders, the better you are able to realize: Wait. This is safe. This isn't like being back in combat."

Of course, you already know it's safe on one level, he added. But down deep, it can take time for your traumatized brain to figure out what's safe and what isn't.

The strategy shouldn't be taken to an extreme, Erbes said. He wouldn't send a combat veteran suffering with PTSD to a military base. Depending on a client's progress, he might advise him or her to go to the fireworks show - but not this year.

"You want to work your way up to these things," he said.

Both Marshall and Roemhildt said their symptoms lessened over time, although even now, Marshall said, he's always in the "fight, flight or freeze mode."

Neighborhood fireworks used to push him into a panic attack or a flashback, Roemhildt said. If he's startled, the blast of fireworks still can cause him to flinch.

"But I do want to stress ... never once through all of these kind of trials and tribulations that I was going through when I got back, never once did I expect or want my neighborhood or my neighbors to not celebrate Fourth of July like they always have.

"I always knew that this is what we do in America, is we light off fireworks."