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The Boston Globe

Metro

Evan Horowitz

How many fireworks do we use on Fourth of July?

Fireworks over the Charles River.

Globe File/1997

Fireworks over the Charles River.

The Fourth of July commemorates independence, liberty, and opportunity. But it’s also about fireworks. Lots of fireworks.

The sparkler you purchase in town may not seem that powerful, but if you gathered all the fireworks Americans will set off this week they’d weigh more than the Statue of Liberty, cost more than a Powerball jackpot, and release more energy than 100,000 bolts of lightning.

How many fireworks are we talking about?

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During last year’s Fourth of July celebrations, Americans lit about 175 million pounds worth of fireworks, according to the American Pyrotechnic Association. How much is 175 million pounds? A stack of pennies weighing 175 million pounds would snake out of the earth’s atmosphere, stretch far past the international space station, and extend over 10 percent of the distance to the moon.

Have we always set off so many fireworks?

Before 2003, consumers used many fewer fireworks. But when states started loosening the regulations that limited firework purchases, those numbers shot up, before moderating again in recent years. Over that same time period, demand for commercial fireworks has gone down.

How much money do we spend on these things?

Consumers alone spent about $662 million on fireworks in 2013. That’s more than the state of Massachusetts devotes to early education, and more than that space-snaking stack of pennies (which is worth about $315 million). It is, however, far less than the cost of a modern aircraft carrier.

How much firepower do all these fireworks have?

Fireworks are filled with an explosive material called “black powder,” or what used to be called gunpowder. They need black powder to get off the ground and more black powder to make them burst. About 50 percent of an average consumer firework consists of black powder and other, similar explosives, according to Mike Hiskey, a Ph.D. in explosive chemistry whose company, DMD systems, made fireworks for the Sochi Olympics. With professional devices, it’s more like 90 percent.

Putting those numbers together, we can calculate that inside the 175 million pounds of fireworks there is about 94 million pounds of black powder. And 94 million pounds of black powder contains about 125 terajoules of energy, according to Hiskey. (A joule is a basic unit of energy, just like a meter is a basic unit of length. A terajoule is a trillion joules.) That is more energy than 100,000 lightning bolts.

Does this mean fireworks are extremely dangerous?

Fireworks can be quite dangerous. In 2013, eight people died as a result of firework injuries and 11,400 were injured. That’s an increase over 2012, though the long-term trend has been pretty stable. The risks are particularly acute for young children, because even small fireworks can be more powerful than they appear. The seemingly benign sparklers, for instance, can burn as hot as 2,000 degrees.

What else should I be watching for?

Boston’s big fireworks show will include about 5,000 pounds of explosive material, which roughly translates to the same amount of energy your heart will expend during your entire lifetime. But it’s not the energy that captivates. It’s the bursting beauty of the sky, with its rich colors, stunning sounds, and evanescent shapes. High-quality fireworks rely on a blend of art and science, and the recipes behind them are often closely guarded secrets, handed down from master to apprentice over years and generations.

Still, as you peer up at the blazing sky this Fourth of July, it’s worth keeping in mind the magnitude of American’s passion for fireworks. To celebrate independence day, we set off a massive nationwide explosion that turns 175 million pounds of raw material into a rich display of light, sound, and power.

Evan Horowitz digs through data to find information that illuminates the policy issues facing Massachusetts and the U.S. He can be reached at evan.horowitz@globe.com. Follow him on Twitter @GlobeHorowitz
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