Don't think that fireworks are safe just because they're legal in your area. The largest share of fireworks injuries are caused by Class C fireworks, the kind that are legal in many states.
 
Fireworks Defined

Classes of fireworks
The Consumer Products Safety Commission (CPSC) categorizes explosive devices into Class A, B, or C.

• Class C common fireworks, now known as consumer fireworks (see below), include fireworks intended for general public use.
• Class B special fireworks are now classified as 1.3G explosives and are intended for use only as display fireworks.
• Class A consists of solid explosives, such as TNT and dynamite.

Consumer fireworks
Previously known as class C fireworks, these are also referred to as 1.4G fireworks. According to the CPSC, they are "the common fireworks and firecrackers sold for consumer use. Consumer fireworks include shells and mortars, multiple tube devices, fountains, Roman candles, rockets, sparklers, firecrackers with no more than 50 milligrams of powder (which is about the size of half an aspirin tablet), and novelty items."

Novelty items
Novelty devices contain small amounts of explosive material and are designed to produce sounds or visual effects with use. This category of device includes sparklers, snakes, snappers, tanks, and poppers. Although novelty items are categorized as consumer fireworks, technically speaking they are not true fireworks. While not entirely intuitive, the distinction is important: Six states only allow the use of sparklers and other novelty items by the general public, forbidding the use of any true consumer fireworks. To find out what is legal in your state, see the article below on laws regulating the use of fireworks.

Illegal explosives
While the meaning of this general term is self-explanatory, it is important for you to know the names of the specific devices--often inaccurately referred to as "fireworks"--that have been banned by federal law since 1966. Illegal explosives--usually sold unlabeled--have been deemed in all instances to contain dangerously large amounts of explosive material and should never be used.
 
They include:

• Cherry bombs. As the name implies, cherry bombs are red and round and approximately one inch in diameter. As a "Class B" firework, they are banned from public use, but can be used in professional fireworks displays. There are some types that look similar and produce streams of smoke, but they must be labeled as a "Toy Smoke Device" and not be red if they are, in fact, legal to use in your state.

• M-80s and M-100s. Also red in color, M-80s are tube-shaped and approximately 1.5 inches long.

• Silver Salutes. These silver devices are also tube-shaped, up to two inches in length, and have a fuse either in the center or at one end.