Ozone: Good up high, but bad nearby
Great question (and timely, too!). Yes, the EPA recently proposed to tighten their ground level ozone standard, from 75 ppb (parts per billion) to between 65 and 70 ppb.
But what is ozone anyway? It’s a colorless, odorless gas that can be harmful to human health and plant life. Or, put another way, it’s smog.
But here’s where your question gets tricky. You probably remember not long ago that the ozone layer was shrinking. Yes, that protective layer high in the sky was developing quite a large hole. And you probably remember hearing how that was a bad thing, right?
Now your head is spinning. If ozone is smog (bad), and the ozone layer (good) is shrinking (bad again), what gives?
Don’t worry. You’re not the only one confused.