Perhaps the most common misunderstanding about ozone comes from the fact that, in certain places, ozone is essential to life. When ozone is high above the Earth in the stratosphere, it helps protect life on the ground from solar radiation by scattering incoming ultraviolet rays from the sun. The skin cancer epidemic in Australia, for example, is related to a hole in the stratospheric ozone. But when ozone is closer to the ground (the troposphere), it enters our respiratory system and can cause a variety of mild to severe health effects. An easy way to remember this is that ozone is “good up high but bad nearby.”
Our maps show tropospheric ozone because it poses the greatest threat to human health. The following sections will detail the mechanisms through which ozone is formed, how exactly ozone affects our health, and what we can do to stay safe and healthy.