HazSubs runs approved handler courses for retailers of fireworks. A spokesman said it was fortunate that the age of modifying fireworks was largely a thing of the past.
"When I show a picture of a sparkler bomb, I look around and see if people are nodding and smiling," HazSubs operations manager Aaron Donald said. "Half of the people don't recognise [sparkler bombs] any more."
Mr Donald said people will always need reminding.
"As part of my presentation I bring to people's attention the facts around sparkler bombs and the danger they pose. Changing the characteristics of a firework in any way is against the Hazardous Substances and New Organism (HSNO) Act. If you're altering a firework in any way, that is an offence. So when you get these kids putting a bunch of sparklers together, turning it into a bomb, while they run the risk of maiming, they're committing an offence."
Mr Donald was hesitant to describe tying sparklers together as a criminal offence. "You might be splitting hairs, but if you're changing the characteristic in any way, if you cut the top off and pour the contents into a Coke bottle ... Clearly sparklers say on the packaging 'light only one sparkler at a time'. So if you strap them together, if that's resulted in damage, they could look at that as breaching the HSNO Act."
An improvised skyrocket put two elderly West Auckland residents in hospital on October 4 after it crashed through a window.
Fireworks are permitted for sale for four days prior to and including Guy Fawkes Day. This is the period beginning November 2 and ending at the close of business on November 5. Restrictions mean no more than 50 sparklers can be purchased mixed in with bulk packs.NZME.