Sparklers and backyard fireworks expose users to breathing heavy pollutants, and parents should consider the health implications for children, a study has found.
A study by researchers from the University of Auckland has found playing with a sparkler for eight minutes is the equivalent of breathing a day's air pollution.
It also found backyard fireworks can emit harmful metals like arsenic, lead and chlorine.
Most previous studies into how much pollution is created by fireworks have focused on big professional events, but backyard fireworks are still common in New Zealand.
The study's lead, Dr Joel Rindelaub, from the University's School of Chemical Sciences, says children are particularly vulnerable to particulates in the air as they breathe a higher air volume proportional to their size.
And small fireworks are often marketed as being 'safe' for children and pets.
Instead, they've been found to breach safe air quality guidelines.
"We looked at sparklers specifically because they're often marketed for use around children, because they might be a 'safer alternative', when in fact as far as air pollution goes it might not be the case because of the extremely high levels of smoke particles that are generated from these."
They found 'personal fireworks', such as sparklers, smoke bombs and ground spinners all produced "extremely high" levels of particulates.
Air samples were also taken in Henderson, and showed particulate matter in the air rose more than 75 percent over the 12 hours of Guy Fawkes night.
"This study shows that pollution from fireworks over the Guy Fawkes celebrations is higher than we expected, and that it can have a short but significant effect on people breathing in the fumes," Dr Rindelaub said.
"It is definitely something that we should research more, and there should be a level of awareness for parents, about exposing their children to these types of smoke events."