There are two general classifications of fireworks designed produce effects: 1.3g explosives are commonly called “display” fireworks and 1.4g explosives are “consumer” fireworks. ( http://en.wikipedia.org/wiki/Fir…)
What’s you’re asking is generally impossible without talking about each type of firework. However, the general hierarchy of danger goes like this (most dangerous to least):
1) Display or 1.3g fireworks: These require a license and are regulated by the ATF. Consumers should not play with these. Those episodes in the news where a trailer blows up and people die is this stuff.
2) Illegal / bootleg fireworks: Those brought in from Mexico or constructed by hand at home. We in the fireworks business call these “bombs” as they present that much danger to consumers. If classified, these would be considered 1.3g fireworks or more.
3) Illegal or overloaded product labeled as 1.4g: Some importers bring these in. You’ll easily tell this product because it just seems too good to be true. An easy trick importers use is placing flash powder in the shells, which has the effect of a bigger, faster burst but is also just illegal in certain quantities in 1.4g consumer fireworks. ( http://en.wikipedia.org/wiki/Fla…)
4) Legal 1.4g product: This includes the full line of products legal in the USA. (see above wiki link for information on what’s legal and not.)
In this category, different items are more or less dangerous. This is my experience with them.
a) Stick rockets and missiles with fins: These items, illegal in many states, propel themselves into the air. They are projectiles and have a habit of going in unforeseen directions easily.
b) Wire sparklers: Sparklers are commonly misused as people give them to kids and don’t supervise the kids. That’s not a problem with wire sparklers, but the parents who are just bad parents. However, wire sparklers cause many burns each year that could easily be avoided with supervision.
c) Aerial shells / reloadables / firecrackers / ground novelties: You basically have to work really hard to hurt yourself with these items. Do something stupid like don’t follow the directions, hold them in your hand, explode in your mouth or this type of crap:
However, the M-80’s and Cherry Bombs of the 1950s are long gone. We, to some extent, sell the illusion of danger in the consumer retail fireworks business these days. That’s fine with me and I sleep well at night.
5) Legal 1.4g novelties: These are boring. They’re snappers, poppers, etc and the stuff commonly sold in the party aisle at your local discount store.
Ultimately, fireworks can always be safe if you buy 1.4g stuff from a trustworthy vendor and avoid being an idiot.