We know you were wondering what happened to all those black balls in all the kids’ playgrounds around the country, and we tracked down the answer – they were all stolen by the Department of Water Protection in Los Angeles. Yup, all 400,000 of them!
Turns out that when chlorine and bromide are exposed to sunlight they react to make a deviously friendly sounding carcinogen called bromate. Chlorine is used to disinfect public water and bromide is naturally found in ground water, so Los Angeles’s Ivanhoe Reservoir had to find a way to shield the water from sunlight and prevent this chemical reaction from happening. And what they came up was something that looks really cool.