100-word explainer: When is ozone bad?

In 1987, countries worldwide signed the Montreal Protocol to protect the depleting ozone in the atmosphere. Ozone/trioxygen (O₃) is a gas that absorbs the sun’s ultraviolet – harmful rays linked to skin cancers. Montreal Protocol may have helped recover atmospheric ozone. However, high levels of ozone aren’t always good.

Breathing ozone can damage lungs, causing breathing problems. Thankfully, the atmosphere contains several layers, and only low percentage ozone is present near the earth’s surface or the “troposphere”. The ozone layer – containing 90% atmospheric ozone – is in the “stratosphere” 10-50km above the surface.

Therefore, the question should be: where is ozone bad?

Tags: atmosphere, environment, Montreal Protocol, ozone, stratosphere, troposphere