An example is the YoYo sparkler brand that was recalled in 2015, on the day before July Fourth. The reason? The sparkler ignited too quickly, causing second-degree burns to at least three consumers.

Products that have no CE mark (or a fake one) also pose an enormous risk. Combustible powders can cause damage and sometimes even death if even the slightest thing goes wrong. A few potential dangers of fireworks are inadequate warning labels, premature explosions, improperly loaded powder, and unpredictable flight paths.

For products that emit special effects, the resulting recoil might be extremely dangerous, for example, when burning down on boats or with defective launchers. It is also crucial to determine the impact energy at head height, i.e., when someone bends over the product.

Pyrotechnic tests are conducted to prevent such incidents. Technical principles determine the legally accepted risks for both life and property.

These principles are also reflected in the legislation to ensure maximum safety and reliability. The law states that each pyrotechnic article must attain the performance characteristics specified by the manufacturer to a body notified to the European Commission.

Each pyrotechnic article must function correctly when used for its intended purpose. In addition, each pyrotechnic article must be designed and manufactured in a way that it can be disposed of safely by a suitable process with minimum effect on the environment.

Source: https://certrust.eu/en/news/dangers-of-faulty-fireworks