Can someone summarize how CFCs achieve the result of depleting the ozone layer?
When I was a kid someone pointed out that CFCs were quite heavy and it was not possible to make it up to the ozone layer. Also, my kid logic considered the science experiment where the teacher showed us a basketball with a light shining through a peg-board onto. At the polls the circles were elongated, thus demonstrating how less light (therefore less radiation) hits the poles.
The fact that the hole in the ozone layer is only at the poles, and according Wikipedia [0], the ozone layer absorbs "97 to 99 percent of the Sun's medium-frequency ultraviolet light" [0]. And that I have never heard of any prevailing wind patterns [1] that would send _all_ of the CFCs in the world to one or two locations, means I have questions...
Two facts seem to make me think there's a flaw in blaming CFCs for the ozone hole.
1) It may simply be a naturally occurring phenomenon because there simply is less ultra violet radiation there. (ie, ozone may exist in part because of ultraviolet radiation, not in spite of it)
2) If CFCs are causing the hole, then shouldn't there be holes right above the factories that make the stuff? (or some similar localized affect first before a distant one?)
Another science experiment from 7th grade, our teacher sprayed a scented mist in the corner of the room. And described the process that eventually (because of entropy) the mist would disperse evenly throughout the room. Claiming a gas would collect in one spot is to claim that the scented mist would disperse and then regather, which is a similar claim to the CFCs. Sure pollution air can gather, but it's in valleys, not the sky.
Consider all the pollution from really polluted cities and factories all over the world, I've never once heard a distant affect claimed from some of these cesspools, yet, somehow CFCs pollute unlike any other gas/chemical known to man?
I don't believe in magic, so there has to be an experiment done to show how CFCs get to the south pole and fly straight up thousands of feet, and then, and only then, do they react with the ozone... something is amiss.
I want to point out, just for the record, why I think you are being downvoted, so that you aren't discouraged and others learn from it. Not to shame or to point fingers. A well functioning community doesn't point fingers or shout down.
It's also OK to ask questions, in some vein to what you do here, but your comment is accusatory and poorly informed. You are simply assuming everyone is wrong, based merely on superficial, self-described "kid logic". Sometimes people are wrong, so that's OK to question, but in this, you've taken it a bit far. There is a lot of well-established science on the effect of CFCs on the Ozone layer. It's pretty much cut-and-dried--much better established, even, than smoking causes cancer. Other posters have replied with actual facts, but I just wanted to post a note that would maybe contextualize the shock of getting a highly negative rated comment and maybe help make it clear to onlookers why we prefer informed discussion here.
>There is a lot of well-established science on the effect of CFCs on the Ozone layer
Yes, and at one time doctors and scientists _all_ agreed smoking was ok for you. And even doctors recommended it for some conditions.
I don't have a problem with getting negative votes, but I have started off discussions with a simple question "why is this a certain way?" and got down voted anyways, and the discussions dragged out.
This time, I figured I'd put all my logic in one lump, instead of spreading it out in the discussion.
Just been reading about Feynman recently, and how many times he was shouted down, accused, etc, just for asking questions about "well established" science.
The problem is that you are holding in one hand currently accepted mainstream scientific thought, and in the other, your "kid logic," and treating them equally.
If you want to learn more you need to learn more - which is to say that it's fine to question the current scientific literature but you better be reading the current scientific literature and not basing it on a grade school Earth Science experiment you saw when you were 7 years old.
I know very little about this realm of science, but I know enough to trust the accepted mainstream.
Feynman was shouted down at times but he was an Ivy League educated Nobel laureate physicist discussing physics. That's probably not an appropriate comparison for your HN comment.
I made statements that most claim are ignorant, which I will abide by, and mentioned that Feynman said to ask questions.
Maybe you people are the ones Feynman was criticising? He certainly wasn't hard on ignorant people looking for answers, he was hard on smart arrogant people who thought they couldn't be wrong.
>Chlorofluorocarbons (CFCs) are heavier than air, so how do scientists suppose that these chemicals reach the altitude of the ozone layer to adversely affect it?
>Although the CFC molecules are indeed several times heavier than air, thousands of measurements have been made from balloons, aircraft and satellites demonstrating that the CFCs are actually present in the stratosphere. The atmosphere is not stagnant. Winds mix the atmosphere to altitudes far above the top of the stratosphere much faster than molecules can settle according to their weight. Gases such as CFCs that are insoluble in water and relatively unreactive in the lower atmosphere (below about 10 kilometers) are quickly mixed and therefore reach the stratosphere regardless of their weight.
That article says this:
"Because CFCs are so long-lived in the lower atmosphere, there is ample time and opportunity for them to become well mixed and eventually to reach the stratosphere."
They all go to one place? Consider the plastic patch in the Pacific, even there, there are currents that move everything there. I've never heard of currents in the air that push everything to the south pole, and then straight up. In fact, I'd tend to believe the air goes up at the equator, and down at the poles (in general).
>chlorine and bromine reactions to produce the ozone hole in Antarctic springtime
Why isn't chlorine and bromine considered just as bad as CFCs, if they are in fact the chemicals causing the problem?
>...most of the emissions occur in the Northern Hemisphere."
>...winds and convection redistribute and
mix air efficiently throughout the troposphere on the timescale of weeks to months*
The paper indicates that there's an equal amount of these gases all over, and that they _aren't_ congregating at the south pole.
Yet, go read the comments on this board, so many people that shout me down don't seem to know this. It's incredible how so many "smart" people are convinced of something, and get raging mad when questioned. Is it because they believe it without actual proof, or haven't researched it thoroughly themselves?
>Stratospheric air motions then transport these gases upward and toward the pole in both hemispheres.
One guy here claimed it was "mountains" that moved the air. Which is silly, because of all kinds of reasons, the least of which is that mountains would only cause a localized updraft, not a planet wide updraft.
I am starting to think HN is fully of "true believers" that will hunt anyone down for questioning anything at all.
There are references in this document to other sources that are not included here. And obviously to question many scientists work these days is tantamount to blasphemy regardless.
>Once formed, PSC particles fall to lower altitudes because of gravity.
Why does gravity affect one type of element but not others?
>The most common source of CFCs are refrigerants, but fire suppression systems for aircraft and aerosols also emit CFCs into the atmosphere.
How much CFCs in the air does it take to create a hole _and_ maintain that hole for decades? This is almost where every discussion from the effects of homelessness, government budgets, wars, etc... all fall apart. No one has any real numbers. It's all "guessing", yet we are "certain" enough say "don't you dare question the orthodoxy".
>"...the highly reactive chlorine gas ClO remains chemically active for a longer period, thereby increasing chemical ozone destruction."
51.4524 g/mol
Chlorine Monoxide, ClO (The CFC gas from the article)
70.9056 g/mol
Cl2 (mustard gas)
44.0095 g/mol
Carbon Dioxide, CO2
14.006747 g/mol
Nitrogen, N
18.01528 g/mol
Water, H2O
Again, I am an ignoramus, but ClO looks to be quite a heavy gas. Cl2 stayed in the trenchs in WWI, carbon dioxide is heavy enough to pour like "water".
Yet the claim is that PSCs (which are made of water) "fall from gravity" yet their molar mass in a fraction of the other gases. Again, I think it's possible to have every gas everywhere. But a single gas 4 times heavier than something that "gravity" pulls from the sky, stays up in air for months wreaking havoc?
I will just point out about the gas diffusion that up to ~100km or so above ground turbulent mixing is the prevalent force. You can look at concentration of argon gas (Ar2 ~80g/mol) which also does not change in that altitude.
About the PSC particles 'falling from gravity' keep in mind these are no longer gases (the operative word is 'particles') so you want to look at their density not molecular weight. (Simplistically, one mol of any gas is 22.4 L while one mol of water/ice is ~0.018 L.)
The reason they have the strongest effect there, and not locally where they're produced or globally in the stratosphere, is because the stratosphere is very dry and only in the extreme cold of a polar winter can stratospheric clouds form. The particles in these clouds catalyse the reactions that allow a each free chlorine molecule to destroy many ozone molecules.
That's also why the hole is worse in the Antarctic. It is colder and has more polar stratospheric clouds.
I'm glad RobertRoberts asked those questions here. Some people have answered in useful educational ways and I've learned. Taken to its logical conclusion "just Google it" more or less means comment threads and places like HN may as well not exist.
Also personally I don't see strong evidence that the questions were asked to stir up trouble and not to learn. People have quite a wide range of ways of using language and expressing themselves, and I know myself that when I'm talking to someone who probably knows more about me than a certain subject, and that my assumptions are probably on shaky ground, I'll still voice my arguments against what they're saying because they will be able to quash them. Otherwise those same arguments will probably drift back into my head later on and make me start doubting again. I've tended to find that the minds I enjoy interacting with the most have been ok with this as they want to share and test their knowledge.
That seems like a valid explanation for the "start" of a hole if there was a continuous stream of _only_ CFCs and chlorine.
Doesn't the ozone gas itself get blown around in the wind also? Wouldn't this mean that ozone would eventually fill the hole back up unless there was a steady stream of CFCs/chlorine to that one spot?
CFCs effectively function as a catalyzer and aren't consumed by the process, hence the hole is more of a Ozone sink. Wikipedia explains the effect of large-scale transport in the stratosphere well: https://en.wikipedia.org/wiki/Ozone_layer
During the polar winter, when the necessary polar stratospheric clouds can form for ozone depletion to occur, the polar vortex also strengthens which tends to isolate the polar stratosphere. During the summer, the vortex weakens, mixing occurs and the ozone depletion over the pole is reduced (the "ozone hole" is seasonal). In fact, as this occurs in the southern spring, areas of ozone-depleted stratosphere drift over inhabited lands to the north.
More CFCs also enter the polar stratosphere through this mixing, though, ready to start the cycle again next polar winter.
Remember as you read these arguments that the wide consensus of scientists is that CFCs cause ozone breakdown.
And the only reason there is any disagreement at all is because billionaires and corporations pay for disinformation. They amplify the tiny number of scientists that disagree, and fund conferences and media to push this false story. Why? Because oil and gas companies make money on climate inaction. So they spend marketing money to sow doubt. There’s no significant organic climate doubt- the push comes from oil and gas funding.
Watching “Merchants of Doubt” is a good start because oil and gas company disinformation on climate follows the same playbook as tobacco and asbestos companies used.
First, I've never heard anyone doubt the ozone layer issue, I've never read anything negative or even looked into any skeptics on this. I didn't even know they existed.
So claiming that I am influenced by some mega-corp's propaganda isn't relevant.
I just found that basic science points out flaws in this theory, and came here to bring up the issue.
Arguments are meaningless, on either side. Chemically speaking I don't doubt that CFCs can react with a whole lot of gases. But to claim that fly all over the world to one spot? And congregate there forever?
>"Although the CFC molecules are indeed several times heavier than air, thousands of measurements have been made from balloons, aircraft and satellites demonstrating that the CFCs are actually present in the stratosphere. The atmosphere is not stagnant. Winds mix the atmosphere to altitudes far above the top of the stratosphere much faster than molecules can settle according to their weight"
Still doesn't explain why the hole is one single place, and hasn't moved for decades.
Later it says this:
>"...and some heavier than air (argon, krypton), which show that they also mix upward uniformly through the stratosphere regardless of their weight, just as observed with carbon tetrafluoride."
I will repeat the interesting part: "uniformly through the stratosphere". This fits with the science I learned. Gases disperse, not collect.
Gases don't go to one place; they go everywhere including that place. Attention to the ozone problem is what leads the discussion in a direction of asking or explaining "how CFCs got to the poles." Nobody asks how CFCs get to, I dunno, 15 miles above Scranton. But the lack of asking does not at all imply that there are no CFCs above Scranton. There is extra attention paid to the poles because an ozone hole appears there.
In your spray-can story, the scent doesn't just go from the corner to your nose and concentrate there, it diffuses throughout the room. But its effect is noticed at the location of your nose and talked about because there's a human paying attention to smells at that spot. If you asked "How did the smell get to my nose?" you would get the answer, "It traveled there from the corner of the room." Which is correct, but not the whole picture. The question itself is biased to focus on your nose and exclude the rest of the room.
That was the lesson I was taught yes. But consider how much scent would have to be released to smell that same smell for 70 years, across the whole planet.
I've read some articles on this linked here, and I see that there are many claims about what is happening, but in one PDF linked above this statement was made.
>The role of PSC particles in converting reactive chlorine gases to ClO was not understood until after the discovery of the Antarctic ozone hole in 1985. Our understanding of the chemical role of PSC particles developed from laboratory studies of their surface reactivity, computer modeling studies of polar stratospheric chemistry, and measurements that directly sampled particles and reactive chlorine gases, such as ClO, in the polar stratosphere"
I get that science has to extrapolate effects, because they simply can't sit in the sky and test the air all day long, it's not possible. But go look through history, how many times have scientists thought they understood something until later they changed their minds when more data was available.
Note the source and timing of the ozone hole discovery:
>* Joe Farman of the British Antarctic Survey discovered the Ozone Hole in 1984"
We have a record of only 27 years of likely minimal data (from what I have read, no one was looking for a hole) where a difference was only discovered at the end of this data set, to which all the conclusions we have now are based. And everyone replying to me is saying this is absolutely settled science? No room for questioning this at all?
Sure, question away, but if people are supposed to agree with you, you kind of need to supply some data or evidence. Skepticism is more than just saying "nothing is really known for sure" or "people have been wrong before." That argument won't overturn the prosecution's case in a court of law for example. What they test for in court, and in science, is reasonable doubt. Give them a reason to doubt, and absolutely they should doubt. People should reconsider their opinions when presented with contrary data. The problem is that you're not presenting any data. The people you're arguing against, have presented data.
At their peak in 1989 before the Montreal Protocol went into effect (and a strangely coincidental multi-year observed trend began of rising ozone concentrations over Antarctica), CFCs were at a concentration of about 2 parts per billion. 70 years of humans releasing them worldwide could absolutely produce that, especially when you consider the long lifespan of those molecules. And they're a catalyst for the ozone breakdown reaction, not one of the reagents; so like most catalysts, they don't get used up, and like most catalysts, there is very little required in the first place.
The classroom experiment might be leading you to overestimate how much CFC output would be required. Probably because the threshold concentration required for half of people to detect a smell -- let's say of ammonia, like after cleaning something with it, or in your cat's litter box, or near a place where people have been pissing -- has to be about 5 parts per million or 2,500 times as much as the peak CFC concentration in 1989. For ethyl alcohol, that cops seem able to smell like bloodhounds when they pull you over, the odor detection threshold is about twice that, or 5,000 times the peak CFC concentration. On the other hand you can smell hydrogen sulfide at only about 20% of the CFC amount, so hey. Maybe it's not a relevant experiment? Except to illustrate the concept of diffusion, which I already addressed satisfactorily, but now your concerns have shifted like a moving target to something else.
How quickly an answer was found in 1985 has nothing to do with that answer's veracity. If a mosquito bites me in the ass, I figure it out right away; that doesn't mean there's no mosquito on my ass. How long an answer remains the accepted answer has nothing to do with its veracity either, which I think is what you're pointing out, but that also cuts both ways; its longevity doesn't falsify it, for example. If I'm right-handed for 40 years do I start to doubt my "handedness" because it didn't change often enough over the years? Because it's suspiciously consistent?? If anything the opposite happens, and it's the same in the science world: There are many professional, honest and earnest people out there making measurements and reporting the results. And if someone made a discovery that could overturn the prevailing ozone depletion theory, there is every incentive both professional and otherwise, to do so. That person only has to publish their data.
Yes, that was about how disinformation gets into public debate and into the media.
Carry on. Seems like the physics discussion above is addressing the science questions you had.
Edit to add: because of the alliance in the US between billionaires and Christians, in my experience a lot of christians hear these kind of science denial ideas as they are growing up. (Not saying this is you, just providing context for international HN readers)
It was teachers in Oregon, decades ago when this came up there was lots of talk, but very little "discussion". (late 80s early 90s)
This was back in the day when they were calling the internet the "information super highway" and we had been sharing the anarchists cookbook on BBS for years already. The ozone hole was brand new and came and went quickly. Haven't heard anything really about it until now.
It's odd how so many assumptions about people's experience and beliefs cause such harsh reactions.
Maybe review the wacky correlation between CFC use and disuse and the ozone holes?
Anyway, note that the atmosphere isn't perfectly partitioned by mass (or do you run on Nitrogen?) and that the poles naturally tend to have less ozone for other reasons.
It's bizarre that you give more credence to your reasoning from limited facts than to the conclusions published by people trying to do real science. Here's an "earth scientist" answering your question:
Then why are people mad at me for asking about it? Plenty of other commenters claim I am stirring the pot, how is this possible if there is no controversy?
You say you are "asking about it" but really you demanded that people reconcile your ill-informed reasoning with the pretty well established science. That's not a controversy, it's trolling. Maybe you did it by accident, but it's trolling.
As I mentioned before, I've haven't read any of their stuff. All of my questions are 30 years old, and only thought to ask this here because I didn't even know there was any controversy on this subject.
But I guess asking logical questions is frowned upon if someone else disagrees with the establishment and if you even ask the same questions is automatically guilt by association.
> But I guess asking logical questions is frowned upon if someone else disagrees with the establishment
Yes. Challenging accepted knowledge on HN is a quick way of getting downvoted to oblivion and, in some cases, shadowbanned. (I've seen a couple of examples of the latter.)
No, nothing is amiss. There are literally decades of scientific research around this topic, and far more thought went into its conclusions than a 7th grade science experiment.
>"...far more thought went into its conclusions..."
Well I did some research, I don't really agree. The "ozone hole" was discovered in 1984 by Joe Farman, and the cause was concluded by 1985. Not of lot of time there. And how many people have the resources to independently verify this?
I am sure there's likely a computer model that could be used right? That is how it was done in 1985.
To address just the light-through-the-pegboard objection, recall that the earth's axis is tilted with respect to the ecliptic. This results in the polar regions receiving long days of sunlight during the summer: at the pole itself the sun doesn't set for six months. It's possible that even less-direct sunlight would have a more pronounced effect over such a long duration.
You are addressing a theory I have though, not established science. Even if the sun get's 24 hours of sun, you can see from many photos of this event the sun is extremely low in the sky. Just from having kids at the pool I can tell you the difference in UV amounts between even noon and 3pm is _dramatic_.
I'm just pointing out that the physical intuition you have from looking at a pegboard is incomplete. That's not the only way, either. The ozone layer is above all terrain and 99% of the atmosphere, so it receives direct unfiltered sunlight. Neither time of day nor latitude is relevant at this altitude. The only thing that blocks the sun is the rotation of the earth, which as we've observed has different effects in polar regions than in e.g. the equatorial region.
Gosh physical intuition can be misleading! It's almost as if it would be better to take actual measurements of sunlight, like many scientists have done.
I would think it is beneficial to be more informed before asking questions and subsequently disputing all of the replies you get with more questions. The problem is that if you don't know enough, you often can't really ask the right questions, so by asking uninformed questions (and giving the logic behind those questions far more credit than it deserves), it's an exercise in frustration for anyone else. Comparing one's lack of understanding to Feynman's informed questioning doesn't really help either.
You seem extremely interested in questioning or learning further about this issue (great!) but I'm surprised that curiosity hasn't led you to read any of the science for yourself?
Trying to dispute established scientific conclusions without knowing or learning at least a baseline of the science involved in reaching those conclusions seems quite futile, IMHO
I also don't understand where you get the idea that there's an existing controversy (maybe I misunderstand, if so, sorry)? The very few that dispute the fact that CFCs deplete ozone are typically very conspiracy-theorist-based and unscientific- the fact that these few disagree with established science does not in any sense create a "controversy"- are you imagining one?
I didn't think there was a controversy until people started telling me there was one today.
I get it, I simply don't understand the topic well enough to discuss it. My original post was in retrospect a mistake. I don't agree with conspiracy nuts, I just thought something was odd and decided to question it.
I have read a few articles on this today, and it just raised more questions, and after learning some things, I see that some other comments are actually wrong, yet still happy to vilify me.
I understand there is a social dynamic on HN at play here, just need to learn the rules better.
Don't be discouraged! The quickest way to learn is how you've done it here. Post something egregiously wrong, and wait for us HN know-it-alls to pounce. Don't worry about the internet points; they're cheap compared to new knowledge. Of course, HN would be tedious if it were full of this sort of thread, so the downvotes are certainly appropriate. I would have cast some myself had others not already done so.
Thanks, for the first time I figured it's ok to get downvoted into oblivion and just follow through with some of the reading without concern for voicing things the way required to get upvotes.
I did learn quite a bit, but also I found that some comments were wrong on the facts they were throwing in my face. I value learning more than social points, but I do appreciate the nod.
As I read the comments here, I was idly pondering why there is no vocal ozone-depletion denial community that is actively trying to repair the unfairly tarnished reputation of CFCs - as we have with climate change. /s
Until I read the parent comment, my working theory was that CFC production was never backed by politically powerful aged billionaires and despotic states in the way that carbon production currently is. But it strikes me that the real reason is probably that the problem was identified and addressed back in the 1980s, before the internet gave a platform to everyone who wrongly believed them self to be an expert. Its useful to be reminded that things were once (for good or bad) different.
The internet is hear now, I don't even want to search out this as a conspiracy theory, I don't have the energy or the time to care.
I am fascinated by changes in science. Like how no one knew how fermentation existed, and that the word yeast, fermentation and leaven all have the same root meanings. Louis Pasteur came along and went to France to study the grapes and vines to find how yeast was produced.
And how his discoveries helped lead us out of dark age of zymotic disease theory. And how doctors at one time didn't wash their hands, yet deny today that their practice was once monstrous and bestial, yet chiropractors are the new "evil".
The thread of logic and evidence is incredibly fascinating. And so I had similar questions arise with the ozone layer. Some things didn't seem to add up, so I asked about them here.
The links you post and their sources carry plenty of evidence to support CFCs being transported to the poles, and as you mention simply because less ozone is create at the poles, the effect is observable at that point.
How do you propose to reproduce the earth's atmosphere at scale outside of a simulation?
Am I wrong in suspecting that you have an ulterior motive for trying to sow suspicion regarding ozone depletion even though the answers to all your questions are one search engine query away? Wikipedia's article on ozone depletion explains why the hole is where it is and provides hundreds of citations for your consideration.
No, I get it, there's something I am simply missing. I am learning that this simply is not the right forum for certain questions. I really should have googled this topic and read some articles.
Or at the very least made my original post just the first sentence and left it at that.
Thanks, those were quite informative. But statements like this on basic chemical reactions doesn't help much:
>The catalytic stratospheric ozone destruction by CFC's and other compounds is almost certainly too complex to fully replicate in a laboratory with current technology.
I've read enough today to know that the stratospheric clouds, temperature, lack of light during the winter and spring months in Antarctica, etc... are all part of the formula for chlorine gases and bromine to cause the depletion of ozone. How is this so complicated it can't be replicated? This smells.
My high school chemistry class had us doing endless formulas on paper showing interactions between chemicals. They were all known and predictable.
But that's fine, I am learning to accept that I just don't understand enough chemistry or science to question these kinds of things. But I appreciate the links, though the PDF disagrees with the Stackexchange posting.
Thunder storms very quickly lift particles sometimes as high as 60,000ft, and there's other phenomena such as mountain lee waves that are mixing air in excess of 120,000ft, well into the Ozone layer.
Do thunder storms do that consistently year after year to the same location with only one type of pollutant? Cause I've never heard of any other kind of pollution pooling at the poles, why only CFCs?
Also, if mountains do it, then why aren't there ozone holes above mountains?
are you a scientist, or just a layperson using intuition to guess at why CFCs wouldn't actually damage the ozone layer?
The reason I ask, is because the way you are asking questions makes you look like a layperson using intuition to guess something that scientists already understand fairly well.
Yep, a layperson. And I got a shitstorm of comments on here because I didn't think to google anything first, and I had no idea there was any controversy on this subject at all.
Yeah, it was obvious. Your line of questioning looks a lot like random conspiracy theorists: full of basic lack of scientific rigor. Beyond just Googling facts, making intelligent conversation around complex scientific issues is hard if you don't have a foundation in scientific thinking.
as an example, you posited that CFCs are dense, and thus why would they interact with the ozone layer? That is simple intuitionist thinking - but it ignores a ton of knowledge about how particles mix and disperse in the real world.
As others have said earlier in the thread – CFC's doesn't pool at the poles. The processes that creates ozone holes require certain conditions (extreme cold and darkness) that only occur by the poles. (https://en.wikipedia.org/wiki/Ozone_depletion)
When I was a kid someone pointed out that CFCs were quite heavy and it was not possible to make it up to the ozone layer. Also, my kid logic considered the science experiment where the teacher showed us a basketball with a light shining through a peg-board onto. At the polls the circles were elongated, thus demonstrating how less light (therefore less radiation) hits the poles.
The fact that the hole in the ozone layer is only at the poles, and according Wikipedia [0], the ozone layer absorbs "97 to 99 percent of the Sun's medium-frequency ultraviolet light" [0]. And that I have never heard of any prevailing wind patterns [1] that would send _all_ of the CFCs in the world to one or two locations, means I have questions...
Two facts seem to make me think there's a flaw in blaming CFCs for the ozone hole.
1) It may simply be a naturally occurring phenomenon because there simply is less ultra violet radiation there. (ie, ozone may exist in part because of ultraviolet radiation, not in spite of it)
2) If CFCs are causing the hole, then shouldn't there be holes right above the factories that make the stuff? (or some similar localized affect first before a distant one?)
Another science experiment from 7th grade, our teacher sprayed a scented mist in the corner of the room. And described the process that eventually (because of entropy) the mist would disperse evenly throughout the room. Claiming a gas would collect in one spot is to claim that the scented mist would disperse and then regather, which is a similar claim to the CFCs. Sure pollution air can gather, but it's in valleys, not the sky.
Consider all the pollution from really polluted cities and factories all over the world, I've never once heard a distant affect claimed from some of these cesspools, yet, somehow CFCs pollute unlike any other gas/chemical known to man?
I don't believe in magic, so there has to be an experiment done to show how CFCs get to the south pole and fly straight up thousands of feet, and then, and only then, do they react with the ozone... something is amiss.
[0] https://en.wikipedia.org/wiki/Ozone_layer
[1] https://en.wikipedia.org/wiki/Prevailing_winds