As July 4th approaches, Americans look to the skies. Throughout thecountry, fireworks will be launched in celebration of the nation'sindependence. But what goes up must come down. Reporter Eric Libbylooks at the environmental issues surrounding fireworks, and efforts todevelop "greener" pyrotechnics.

July 4rth fireworks over Washington DC

Take a group of reactivechemicals, shoot them high into the air, and watch them explode in avery loud, very smoky, and very hot spectacle. This sounds like theexact opposite of an environmentally friendly, or green, activity. Soresearchers are actively assessing the impact of fireworks and workingto make them safer for the environment.
   
Among the chemicalsused in fireworks, perchlorates have drawn attention. These compoundsprovide the oxygen that fuels the explosion. Hydrogeologist DavidJewett of the Environmental Protection Agency points to an EPA studymeasuring perchlorates in an Oklahoma lake after fireworks displaysfrom 2004 to 2006. "They saw a peak in perchlorate concentrationswithin 12 or 14 hours after the fireworks display," says Jewett. "Butthen those concentrations decreased back to background levels over atime period of 20 to 80 days."

Studies have linked perchloratesto impaired thyroid function. While Julie Heckman, executive directorof the American Pyrotechnics Association, acknowledges the potentialhealth risks of perchlorates, she says their use in fireworks does notpose a danger to the public. "The position of the fireworks industry,"Heckman explains, "is [that] the amount of pyrotechnic compositioncontaining perchlorate is pretty nominal in terms of what otherindustries use or discharge. Look at the military, [which is the]biggest contributor," she adds.

Julie Heckman notes that U.S.government regulations prohibit fireworks from containing evenmore-toxic substances such as lead and arsenic. Another concern is theuse of so-called heavy metals to give fireworks their colors. Inparticular, barium - which is responsible for the color green - isextremely poisonous in some forms. Mike Hiskey describes how hispyrotechnics company, DMD Systems, is addressing these concerns. "Webase all our mixes on nitrocellulose, which burns very cleanly, withbasically no smoke, (in)to carbon dioxide, water, and nitrogen. We canreduce the amount of heavy metals in there by quite a bit, like almostan order of magnitude," Hiskey adds. "In addition to that, all of ouroutdoor pyro contains no perchlorate."

Hiskey says there isgrowing interest in green fireworks, especially from indoor concertpromoters and the Disney Company, one of the world's largest users offireworks. Scientists at Germany's Ludwig Maximilian University ofMunich are searching for ways to completely replace barium infireworks. Graduate student Karina Tarantik says it's difficult toproduce the color green with safer ingredients like copper compounds.

"Ifchlorine combines with copper you get blue color and no green. Or ifthe temperature is too high of the combustion you get more red oryellow flame color. So, [it is] quite difficult," she cautions.

Tarantiksays the hardest color to make "green" is, in fact, green. Thankfully,the most important colors on the 4th of July are red, white, and blue.