By Yishane Lee

Every Fourth of July we join the chorus of folks in the healthcare space reminding us all to be safe when it comes to enjoying fireworks over the holiday. While most of the advice centers around avoiding burns and other injuries, fireworks can also permanently damage hearing.

Fireworks can reach 150 to 175 decibels (dB), a literally deafening level causing instant hearing loss if you are too close. At public displays aim for a distance of 500 feet, and we strongly advise using protective earplugs or earmuffs, especially for children. 

Fireworks are especially jarring and stressful for babies and pets. There’s NO safe exposure for babies, so please leave them at home with the sitter. For pets, veterinary and humane societies have many tips, notably to also leave them at home and to consider creating a safe, quiet environment (such as in their crate). You can drown out noise from fireworks at home by countering it with white noise from fans or air conditioners.

Doing something fun and celebratory and ending up with permanent damage to our hearing would be a real bummer. Let’s use common sense—as our friend Dan Fink, M.D., at Quiet Communities says, “If it sounds too loud, it is too loud.”

Blast Waves and the Brain

Independence Day is a celebration of our country’s birthday, and we’re so grateful for the service of our active members of the military and veterans—who are, as we know, disproportionately affected by hearing loss and tinnitus. But now evidence is emerging of additional, severe brain injuries affecting service members.

We know that we hear not only with our ears, but also with our brain. And we already know that loud blasts can cause hearing loss and tinnitus, an area that 2019 Emerging Research Grants scientist Vijaya Prakash Krishnan Muthaiah, PT, Ph.D., has been investigating.

But while loud sounds are a known risk, less had been known about the effect on the brain of shock (energy) waves from weapons.

Until now. The New York Times recently reported on several U.S. Navy SEALs, among the most elite special forces, dying by suicide. A particular pattern of damage was found in their brains from shock waves emitted by weapons fired during the course of regular training—not from enemy action.

The story says, “Nearly everywhere that tissues of different density or stiffness met, there was a border of scar tissue—a shoreline of damage that seemed to have been caused by the repeated crash of blast waves.”

The symptoms—”insomnia and headaches, memory and coordination problems, depression, confusion, and, sometimes, rage”—were sometimes misdiagnosed as PTSD. (Experts are debating whether brain injury as a result of training weaponry exposure led a U.S. Army reservist to kill 18 people in Maine in 2023.)

And the damage from blast waves is likely cumulative, just as with loud sounds:

“Blast waves may kill brain cells without causing any immediately noticeable symptoms, according to Dr. Daniel Daneshvar, chief of brain injury rehabilitation at Harvard Medical School.

“‘People may be getting injured without even realizing it,’ Dr. Daneshvar said. ‘But over time, it can add up.’”

In the story’s Comments section the writer, military reporter Dave Phillips, says he will cover prevention and treatment efforts in future articles. He also addresses how other parts of the body may be affected. He writes:

“The military has long known that the changes in pressure can injure organs that contain gas (digestive tract, lungs) as well as the ears. It was thought that the level of blast released by firing weapons was low enough to be safe, but it's unclear if that is true with repeated exposure over a career. Many of the troops exposed to repeated blasts have problems with their hearts, digestion, and endocrine system. Is that from physical damage to the organs or damage to the brain that regulates them? That's an open question.”

Phillips and the Times created a video to show how a blast wave travels through liquid and damages areas far from the point of impact. 

(We also can’t help but think of the symptoms described by ”Havana syndrome” that affected U.S. government staff and families around the world. It’s still not understood what caused it.)

Most of us can choose our level of exposure to many loud sounds, such as fireworks, so let’s make sure our hearing stays safe. And in the spirit of collaboration, let’s work—through individual choices and larger policy issues like the exposure faced by service members—to better protect our hearing as well as our brains. Have a safe, happy holiday!

2019 ERG scientist Vijaya Prakash Krishnan Muthaiah, PT, Ph.D., was generously funded by Royal Arch Research Assistance.

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