“Times Investigation Exposes Artillery Blast Effects: 5 Key Findings”

When American military planners launched a ground offensive against the Islamic State in Iraq and Syria in 2016, they knew that the American public was weary of long wars in the Middle East, and that the operation would have to make do with very few Americans troops on the ground. So they relied on a strategy that had not been used much in decades: intensive bombardment by heavy artillery.

Military guidelines said that firing all those high-powered artillery rounds was safe for the gun crews. But an investigation by The New York Times, including interviews with more than 40 gun-crew veterans and their families, found that the troops came home plagued by insomnia, confusion, memory loss, panic attacks, depression and, in some cases, hallucinations, among other symptoms. And because the military thought the blast waves were safe, it repeatedly failed to recognize what was happening to the troops.

Here are five takeaways from the Times investigation.

To defeat ISIS, the United States relied on artillery crews firing more intensively than any had in generations.

The big howitzers used in the height of the offensive against the Islamic State in Syria and Iraq, from 2016 to 2017, could hurl a 100-pound round 15 miles, and gun crews fired them almost nonstop, day and night for weeks on end.

The strategy worked as intended, and the Islamic State was soon smashed to near oblivion. But keeping the number of U.S. troops involved to a minimum meant that each gun crew had to fire thousands of high-explosive shells — far more rounds than any American gun crew had fired at least since the Vietnam War. Some troops fired more than 10,000 rounds in just a few months.

Many members of the gun crews developed devastating and puzzling symptoms.

Each howitzer blast unleashed a shock wave that shot through the bodies of the troops standing near the gun, vibrating bones, punching lungs and hearts, and whipping at cruise-missile speeds through the most delicate organ of all, the brain.

Members of the gun crews started to have memory and balance problems, nausea, irritability and crushing fatigue. Those symptoms were signs of concussion, but also what anyone might feel after working 20-hour days in the desert and sleeping in foxholes. Crews trained to endure didn’t complain.

The crews were screened for signs of brain injuries after deployment, but those screenings were designed to spot the effects of much larger explosions from enemy attacks — not repeated exposure to blast waves from routine firing of weapons. Few of the troops screened positive.

Crew members who were told they were healthy struggled to understand why they were stalked by panic and sleeplessness. Some thought they were going insane.

When the troops started to act strangely, they were often treated ineffectively or punished.

Nothing in the gun crew members’ records suggested they had ever been exposed to damaging blasts in combat, so when some sought medical help from the military, doctors repeatedly failed to consider the possibility of a brain injury.

Instead, the troops were often told they had attention deficit disorder, depression or post-traumatic stress disorder. Many were given potent psychotropic drugs that made it hard to function and failed to provide much relief.

When job performance deteriorated or behavior turned erratic, many crew members were seen not as wounded, but as problems. They were passed over for promotion or punished for misconduct. Some were forced out of the service with punitive discharges and cut off from veterans’ health care.

Their problems have spilled over into civilian life, wrecking marriages and making it hard to hold down jobs. Some are now homeless. A striking number have died by suicide. Many still have no idea that their problems may stem from blast exposure.

Studies are starting to reveal the risk posed by blast exposure, but progress is slow.

Research suggests that repeated exposure to the blast waves generated by firing heavy weapons like cannons, mortars, shoulder-fired rockets and even large-caliber machine guns may cause irreparable microscopic damage to the brain. Vast numbers of military veterans may have been affected.

But the damage is nearly impossible to document, because no brain scan or blood test now in use can detect those minute injuries in a living brain. Making diagnosis more complicated, many of the symptoms can be identical to those of P.T.S.D.

As things now stand, the microscopic damage from blast exposure can only be definitively documented by examining thin slices of brain tissue under a microscope once someone has died. Tissue samples taken from hundreds of deceased veterans who were exposed to blasts during their military careers show a unique and consistent pattern of microscopic scarring.

The military says it now has safeguards to protect from blasts, but it is not clear that much has changed.

Congress, at the behest of veterans’ groups, recently ordered the Pentagon to start assessing the blast threat posed by firing weapons and to develop protocols to protect troops. But the work is still in progress. Fundamental questions about what level of blast can cause injury and how repeated exposure may amplify the risk still have no answers.

The Army and the Marine Corps both say that they now have programs to track and limit daily exposure for troops. But Marines in the field say they have not seen the new safety programs, and troops throughout the military are still training with weapons that the Defense Department is concerned may pose a risk.