What Are in Fireworks? A Look Inside the July Fourth Pyrotechnics as New Jersey Celebrates New Law

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People watch as fireworks explode in the sky as part of celebrations for Victory Day in Moscow, Russia, on May 9. Maxim Shemetov/Reuters

The Fourth of July is peak summer for many Americans, complete with an activity-packed day away from work, barbecue in the sunshine (hopefully), a beautiful display of fireworks against the night sky and perhaps some hand-held sparklers and noise makers. As of Wednesday, people in New Jersey can now take part in all of the festivities.

Governor Chris Christie, who is extremely unpopular among state residents, signed a bill this week enabling "non-explosive, non-aerial" fireworks to be sold in the state, NJ.com reported. Though bottle rockets and the like are still forbidden, Independence Day revelers will now be allowed to play with items like sparklers and party poppers without fear of fines.

Related: What fireworks to avoid and how to stay safe on Fourth of July

If you're in the Garden State, you can join Americans in enjoying the more than 285 million pounds of fireworks that will be used this year. But before you run out and stock up on pyrotechnics, you may want to learn more about what's inside them.

Fireworks contain any number of ingredients that light up the night. Most have what are called aerial shells inside with gunpowder and stars that are made of explosives and usually formed in small spheres or cubes, according to the American Chemical Society's 2010 report in its Chem Matters magazine. There's also a bursting charge in the middle of the shell that's connected to the firework's fuse.

Once the fuse is lit and the gunpowder reacts, the firework shoots into the air.

"After a few seconds, when the aerial shell is high above the ground, another fuse inside the aerial shell, called a time-delay fuse, ignites, causing the bursting charge to explode," according to Chem Matters. "This, in turn, ignites the black powder and the stars, which rapidly produce lots of gas and heat, causing the shell to burst open, propelling the stars in every direction."

The colors you see come from what are called metal salts. Red fireworks, for example, contain strontium carbonate, while yellow ones include sodium nitrate, according to EarthSky. Sometimes, as Wired noted, antimony trisulfide is added to give fireworks a glittery appearance.

Sound easy to make? Well, don't. As gorgeous as fireworks are—and as much as you may feel like Walter White creating them—pyrotechnics are dangerous. You should just sit back and enjoy the shows put on by professionals.

"Remember these are explosives and that if used incorrectly, can cause irreparable injury and harm," State Fire Marshal Kevin Sehlmeyer told the Battle Creek Enquirerearlier this month. "Certified fireworks retailers aim to make safety their top priority."