When it comes to fireworks, we tend to think about safety in terms of fingers or eyes. A more neglected concern with fireworks is the impact on our health and the environment. Yet, after exploding, the chlorine-based compounds that make for the nice red color in the explosions can transform into cancer-causing chemicals that fall to the Earth. Now, scientists have found a chlorine-free alternative. It could pave the way for a generation of red flares and fireworks that are better for the environment and for people’s health.