Ozone is a formerly hot topic, when they first discovered what was going down with it in the 80's. Today, we know a lot more about it, but fail to communicate this to the general public, as can be seen in the conflicting articles above. There are three aspects of ozone that should be discussed.
- Ground Level Ozone
- Stratospheric Ozone (Ozone Layer)
- Depletion of Stratospheric Ozone (Ozone Hole)
First off, what is ozone in general? Ozone's chemical compound is O3 - it is made up of three oxygen atoms. Oxygen atoms can form up to two bonds with other atoms. Think of it like your typical person with two hands who can hold hands with up to two other people. If you and your sweetheart hold hands just with each other, right to left and left to right, you get the oxygen molecule, O2. When you hear about "breathing oxygen," this is what they mean. If you hold hands with two other people, and they each hold hands with each other, in a triangle shape, that's ozone. It's easier to break you three apart, to tear your hands from each other, as is true with ozone. Theoretically you could have O4 and so on, but these larger molecules get increasingly easy to break apart, increasingly unstable, and are pretty much never found in nature.
The next important aspect to ozone is that of UV light. Ultraviolet light is just the right energy to interact with ozone molecules, either forming or destroying the molecules. High up in the atmosphere, within the stratosphere, the ozone layer absorbs UV light when the UV breaks apart molecules. This protects all life on Earth from UV light, which causes cancer and various mutations. The molecules naturally reform on their own, so (without human interference) the amount of ozone in the ozone layer stays constant. Stratospheric ozone (the ozone layer) is good for humanity.
Low in the atmosphere, in the troposphere near the ground, not much ozone forms naturally. When UV light sneaks through past the upper layers and interacts with pollutants (such as nitrous oxide) it forms ozone. Not enough ozone to block UV light, so it doesn't do much good. But enough ozone to hurt us in other ways -- because it is so unstable, when you breathe ozone in, it interacts with the lining of your lungs and essentially "burns" (oxidizes) your lungs. This is especially bad for people with asthma or lung diseases. Tropospheric ozone (ground-level ozone) is bad for humanity.
To complicate matters more, not only does ground-level pollution help form ozone, other pollutants help destroy stratospheric ozone. Specfically, the chemicals that used to be used in air conditioners, chlorofluorocarbons (CFCs), interact quickly with ozone to break it apart, and then move on to break apart other ozone molecules. This contributed to the current day ozone hole. We have since banned CFCs, which is slowing the destruction of the ozone layer (destroying the ozone layer is the same as creating the ozone hole).
All that's fine and dandy, but it doesn't explain the flip-flopping results that CNN reports. As is often the case, I'm pretty sure it's all a matter of what they measured. The first group (that said the ozone layer is recovering) went to certain specific locations and measured how much ozone was in the ozone layer above those spots on the ground, for the dates 1996 to 2002. They are not up to date, and it's possible things have happened since then. The second group (ozone hole worst ever) measured specifically the size of the ozone hole over Antarctica this year. Perhaps this year was an anamoly?
I think most of the issue is in the locations chosen by both groups. It's possible that most of the ozone layer is getting thicker, but that one section of it over Antarctica is getting worse. What's the overall result if we combine the two groups? I don't know, and I don't think I could without looking at their data in depth and probably doing additional research. Give it a year or so and someone will do that and come up with a whole new set of answers. That's what's great about science -- no one person or group can claim to know what's "right"! :)