Saturday, July 3, 1999 Published at 10:19 GMT 11:19 UK
Fireworks shower toxic chemicals
Salt Lake city celebrations: A shower of dioxins?
By Corinne Podger of BBC Science
Americans and Canadians could finish their Fourth of July and Canada Day festivities in a fog of toxic chemicals after their traditional fireworks displays.
Significant levels of dioxins, which are known to cause cancer, are given off by blue fireworks, according to chemical researchers in Germany.
According to Dr Robertus Vichmann, of Braunschweig Technical University, the patriotic displays of fireworks will shower watching crowds with a cloud of chemicals that are known to cause cancer.
In a paper in the journal Chemosphere, Dr Vichmann said today's crackers, rockets and fountains contain a wide range of chemical additives, including chlorine-based substances.
Copper salts are often added as well, to make fireworks give off blue light. But when these blue fireworks are ignited, he says, they give off a chemical cocktail that contains dioxins.
"We selected some pyrotechnic products and like firecrackers, jumping jacks and so on, which are normally used by the people," Dr Vichmann said.
"We found that fireworks containing copper salts gave off some amounts of dioxins because these copper salts can act as catalysts for the production of dioxins."
Scientists say other fireworks which emit red, green or white light give off less dioxins. But even blue varieties produce only minutely higher amounts of these chemicals.
Instead, Dr Vichmann says his research will help firework manufacturers to maintain quality control limits and that onlookers at displays this weekend can relax and enjoy the show.
"They didn't give off very much dioxins, so it's not dangerous to man and also not dangerous to environment, to the nature, to use these fireworks. So you can have your fun with it."