Last Fourth of July, 9-year-old Grant Pinkstaff was enjoying the annual fireworks display in Tulsa, Oklahoma, with his family when something struck him from above. The boy’s head began bleeding profusely. First responders initially believed the injury was the result of a severe burn, perhaps from a falling firework. But a scan at the hospital revealed that he had been hit by a bullet. Police said the projectile was fired into the air by a nearby reveler.

“It’s amazing that he’s alive,” Annette Pinkstaff, the boy’s mother, said after the shooting. The bullet remains lodged in Grant’s head. His vision was damaged, and he suffers from severe headaches.

Over the holiday weekend, Americans will celebrate their country’s independence with barbecues, parades, and baseball games. And some people will fire their guns into the air. If you are someone who might be tempted to do this, please first consider this bit of elementary school-level science: The Earth is surrounded by a gravitational field. Objects launched into the air without enough velocity to escape that field — objects like bullets — always come down. And no one wants to be struck by a falling piece of metal.

Bullets that fall from the sky maim and kill. In 2012, researchers from the University of California, Davis, studied the the phenomenon of stray-bullet shootings. They analyzed 284 incidents, in which 317 people were killed or injured. Nearly five percent of incidents were the result of celebratory gunfire.

And watching a fireworks display seems to compel some people to take aim at the sky.

Information provided by the private-sector gunshot location service ShotSpotter, which uses audio-visual sensors and other techniques to locate and record gunfire in dozens of cities, recorded a five-fold increase in gunfire from July 3rd to July 5th of 2015.

Here’s what else we found out when we examined this very, very unwise practice.

When do celebratory gunfire incidents most often occur?

According to ShotSpotter, the July 4th weekend is the busiest time for celebratory gunfire in the United States, and is responsible for roughly two-thirds of all incidents.

New Year’s Eve ranks second. On December 31 of last year, Texas State Representative Armando Martinez was ringing in 2017 with his family when the crack of gunfire prompted them to retreat to a garage. Martinez returned outside when the shooting ceased. That’s when he felt a blow to the back of his head, as if he’d been hit with sledgehammer. In fact, he’d been struck by a falling bullet.

Martinez was lucky. He did not suffer serious injury.

He told The Trace that this July 4th, he’ll be extra wary of lead falling from the sky.

“My family and I are taking a lot of precautions,” he said. “I’m going to celebrate inside the home.”

Where do people face the highest risk of suffering an injury from a celebratory gun shot?

The majority of celebratory rounds land without harm. But in areas with high population density, some bullets hit humans.

Each year before the holiday season, police, city officials, and activists from Virginia to Ohio to Florida call on their communities to refrain from spraying bullets skyward. Here’s one public service announcement produced by the police department in St. Petersburg, Florida:

How do bullets shot into the air keep their lethal force?

It’s very difficult to fire a bullet perfectly straight into the air. The physics governing ballistic trajectories mean that rounds fired at angles of 20 to 45 percent in particular can retain lethal force at considerable distance. This is borne out by hospital admissions data from studies in Los Angeles, San Juan, and Pakistan, all of which indicate that falling bullets, when they do connect with bodies, are most likely to hit heads, shoulders, and feet, and can easily do extensive damage.

Data also suggest that falling bullets are several times more likely to be fatal than other gunshot wounds, and that women and children specifically are much more likely to be injured by celebratory gunfire than by other kinds.

If a bullet from a celebratory shot injures or kills someone, how often is the shooter identified?

Not very often. Cases where authorities can precisely pinpoint the location of the gun — let alone identify the shooter — are incredibly rare. reports that in 2013 the city of Birmingham, Alabama, received around 2,500 reports of celebratory gunfire. Only nine arrests were made.

The legal consequences for those who do get caught are also mixed. Charges range from misdemeanor to felony.

After Martinez, the Texas state representative, was hit by a falling bullet, he introduced a bill that would make firing without aim a misdemeanor, and injuring or killing someone as the result of such an incident a felony. It failed in May, but he said he plans to reintroduce the measure as soon as the legislature reconvenes in 2019.

Why do people shoot celebratory gunfire in the first place?

On one level, the answer is the obvious one: It’s recklessness, frequently abetted by drunkenness. People may actually not realize that the bullets they launch into the air will inevitably land somewhere, with potentially disastrous results.

But on another level, there are basic economics at work. Many municipalities ban outright the sale of another Fourth of July and New Year’s staple: fireworks. That means residents have to be able to afford to travel outside city limits or even cross state lines in order to buy them. Meanwhile, ammunition can be plentiful, already at hand, and, in many cases, simply cheaper.

This post is adapted from an earlier article by Patrick Blanchfield.