• Noun: a colorless gas (O3) soluble in alkalis and cold water; a strong oxidizing agent; can be produced by electric discharge in oxygen or by the action of ultraviolet radiation on oxygen in the stratosphere (where it acts as a screen for ultraviolet radiation)
So I'm going to go on and work on preserving the ozone layer, encouraging everyone to recycle.
When I was a kid, we never heard of smog, ozone depletion, acid rain, green house gasses.