Wikipedia
An airbomb is a type of firework. It is simply a concentration of flashpowder in a paper case, that is ejected into the air with a black-powder lifting charge, ignited by a fuse. The flashpowder explodes in midair with a loud "bang" and a bright white flash. Single tube airbombs were banned in Britain in 2004, because they are classed as a cheap, nuisance firework. Multishot airbombs are still legal in Britain. The airbomb effect, a loud bang and flash, continues to be a part of many larger fireworks. Since 1 April 2008, any firework which contains at least one tube containing over 5% flashpowder will be classed under United Nations regulations as 1.3G, with stricter transportation and storage regulation. This effectively means that any firework containing a flashpowder effect will not be legally available for sale after this date. As such, manufacturers are replacing the "bang" with a crackle effect, or are using black-powder bursts. However these are more expensive and don't have the traditional "flash" effect.