Ozone: now a global warming culprit, too

And another problem, in addition to the post immediately below, fueling Arctic warming:

NASA says ozone is contributing to Arctic warming.

Globally, ozone accounts for perhaps one-seventh of the global warming and climate change that carbon dioxide does, Shindell said. However, a new study of climate change over the past 100 years indicates that ozone may be responsible for as much as 50 percent of the warming in the Arctic zone.

Question: While CFCs continue to be phased out, how much ground-level ozone from things such as automobile exhaust survives to be a factor in this cycle?