A bit of background. The layer of ozone (O3) is approximately 15 - 40km above the surface and shields the earth from much of the harmful ultaviolet radiation that bathes the planet every day, specifically UV-B. Quite literally, life could not exist without this gaseous layer.
In 1985, it was discovered that there was a hole in the ozone layer over Antarctica. "Hole" is a bit of a misnomer. It was more like a giant thin spot. Regardless, it was quite shocking to the scientific community and even to the general public. Only 2 years later, an international agreement was established called the Montreal Protocol, calling for the reduction and complete elimination of chlorofluorocarbons (CFCs) which were the main culprit in the ozone depletion. CFCs were used in all sorts of aerosol products, refrigeration and air conditioning systems and other industrial uses. They are very stable at ground level, but no one realized how reactive they were when they floated upwards to the upper atmosphere. The chemistry is a little complicated, with the end result being the destruction of ozone.
So how's the ozone doing today?
Though it no longer seems to make the news anymore, that ozone layer hole is still there and still an environmental threat. Even with the successful world-wide reduction of CFCs, the hole remains and in fact is getting larger. In 2000, the hole was 28.4 million square miles in size and formed much earlier in the season than usual (according to the British Antarctic Survey). The problem is that CFCs take many years to reach the ozone layer and then remain there for up to 100 years. It will take some time before the elimination of new CFCs actually has any effect on our atmosphere.
It does make me wonder why this is no longer even mentioned in the news, when it was the biggest thing going back in the 80s. It took only 2 years to get international cooperation to fight this threat, which is unheard of when it comes to environmental concerns. Why is that? My own opinion is that this hole was measureable and easily understood by the public. It was definable and specific. That scares people, and now that we have done what we can, it's just not talked about any longer. On the other hand, global warming is vague and not easily understood or documented. It can be covered ad nauseum without causing too much of a public scare. That's just my own theory.
My moral: just because you don't hear about environmental problems, doesn't mean they've gone away.