Fireworks consist of shells packed with marble-sized pellets that contain different compounds—substances made up of at least two different elements. When heated, these compounds burn with different colored flames.
“In a burning firework, strontium [Sr] and chlorine [Cl] atoms combine and yield an intense red light,” says Jesse J. Sabatini, a chemist at the U.S. Army Research Laboratory in Maryland. But red fireworks can also produce small amounts of cancer-causing chemicals that contain chlorine.
Sabatini is developing chlorine-free signal flares for the Army. He and his colleagues have found a way to replace chlorine compounds in the red flares with safer substances while still keeping the flash’s brilliant red hue. The same idea could be applied to red fireworks.