Iodine in desert dust destroys ozone

New CU Boulder study shows iodine from desert dust can decrease ozone air pollution but could prolong greenhouse gas lifetimes

Peer-Reviewed Publication


Atacama desert photographed from the airplane.

When winds loft fine desert dust high into the atmosphere, iodine in that dust can trigger chemical reactions that destroy some air pollution, but also let greenhouse gases stick around longer. The finding, published today in the journal Science Advances, may force researchers to re-evaluate how particles from land can impact the chemistry of the atmosphere. 

“Iodine, the same chemical added as a nutrient to table salt, is eating up ozone in dusty air high in the atmosphere,” said Rainer Volkamer, a CIRES Fellow and professor of chemistry at CU Boulder. Volkamer led the team that made precision atmospheric measurements by aircraft over the eastern Pacific Ocean several years ago. The new finding, he said, has implications for not only air quality, but climate, too—iodine chemistry can make greenhouse gases stick around longer and should give us pause to re-think geoengineering schemes involving dust. 

Our understanding of the iodine cycle is incomplete,” Volkamer said. “There are land-based sources and chemistry we didn’t know about, which we must now consider.” 

Atmospheric researchers have long been interested in the observation that dusty layers of air are often very low in the air pollutant ozone, which, when concentrated, can damage people’s lungs and even crops. It seemed that some kind of dust-surface chemistry was eating up ozone, but no one had been able to show that happening in laboratory experiments. Others have speculated about this, but there’s been a lot of doubt, said Volkamer. By contrast, lab experiments have long shown that a gaseous form of iodine can gobble up ozone—but there were only hints of a connection between dust and iodine. 

There were other tantalizing hints about the process in a dataset from 2012, from a series of aircraft flights offshore Chile and Costa Rica. Dust seen blowing offshore from South America had striking levels of gaseous iodine. Volkamer handed the data to then-CU Boulder graduate student Theodore Koenig, lead author on this study. Koenig describes those data as one in a set of blurry photographs shared by atmospheric chemists around the world. In one image, for example, “iodine seemed to correlate with dust … but not absolutely clearly,” he said. Everywhere, dust seemed to destroy ozone, but why? “Iodine and ozone clearly connect, but there weren’t any ‘photos’ of both with dust,” said Koenig, who is now an air pollution researcher at Peking University in China. 

The data from TORERO (the “Tropical Ocean Troposphere Exchange of Reactive Halogens and Oxygenated Hydrocarbons,” a field campaign funded by the National Science Foundation) captured those three characters together, finally, in one image he said, and it was clear that where desert dust contained significant levels of iodine—like dust from the Atacama and Sechura deserts in Chile and Peru—the iodine was quickly transformed into a gaseous form and ozone dropped to very low levels. But how did that dust-based iodine transform?  “The mechanism still remains elusive,” Volkamer said. “That’s future work.”

So the picture is another blurry one, Koenig said, but still, the science is sharper than it was. “I have more questions at the end of the project than at the start,” he said. “But they’re better, more specific questions.”

They’re also very important, for anyone interested in the future of the atmosphere, Volkamer said. Iodine’s reactions in the atmosphere are known to play a role in reducing levels of OH, for example, which can increase the lifetime of methane and other greenhouse gases. Perhaps more importantly, various geoengineering ideas involve injecting dust particles high into Earth’s atmosphere, to reflect incoming solar radiation. There, in the stratosphere, ozone is not a pollutant; rather, it forms a critical “ozone layer” that helps shield the planet from incoming radiation. 

If iodine from dust was chemically transformed into an ozone-depleting form in the stratosphere, Volkamer said, “well, that’d not be good, as it could delay the recovery of the ozone layer.  Let’s avoid adding anthropogenic iodine into the stratosphere!”


Science Advances




Data/statistical analysis


Not applicable


Ozone Depletion Due to Dust Release of Iodine in the Free Troposphere




The authors declare that they have no competing interests

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December 26, 2021 6:04 pm

It would be way more beneficial if these jokers would just snuff themselves and everybody is a winner !

Mike McMillan
Reply to  Streetcred
December 27, 2021 3:04 pm

You misspelled “sniff.”

bill Johnston
December 26, 2021 6:23 pm

“Let’s avoid adding anthropogenic iodine into the stratosphere”. I failed to read anywhere here that mankind is doing the adding.

Zig Zag Wanderer
Reply to  bill Johnston
December 26, 2021 6:35 pm

failed to read anywhere here that mankind is doing the adding.

I think the author may be referring to various schemes proposed by adherents to the CAGW doomsday death cult:

Perhaps more importantly, various geoengineering ideas involve injecting dust particles high into Earth’s atmosphere, to reflect incoming solar radiation.

Reply to  Zig Zag Wanderer
December 26, 2021 9:57 pm

The hubris of “experts” never ceases to alarm me.

They couldn’t help themselves in mucking around with ‘gain-of-function’ viruses, convincing themselves and clueless governments that “we’ve got this”, and look what happened next.

And now they want to “engineer” our atmosphere?

We’re all being set up for an undeserved Darwin Award.

Reply to  Mr.
December 27, 2021 6:16 am

You do have to ask why, when they can’t even control their own digestive systems, they think they can control anything on this planet or elsewhere.

Alan the Brit
Reply to  Zig Zag Wanderer
December 27, 2021 1:02 am

The classic we’ve been putting nasty stuff into the atmosphere so let’s put moor of the same to save us from an imagined upcoming disaster. Sounds to me like true science fiction disaster movie material!!!

Reply to  bill Johnston
December 26, 2021 7:40 pm

The hypothesis is that troposphere ozone resulting from pollution drifts over the oceans leading to increases in atmospheric iodine.

Reply to  Scissor
December 26, 2021 9:02 pm

That is government speak for models…

From the link you provide:

Results from the chemistry-climate model CAM-Chem (Community Atmospheric Model with chemistry”

Alan the Brit
Reply to  ATheoK
December 27, 2021 4:56 am

The only hypothesis here is that of GIGO!!!

Reply to  ATheoK
December 27, 2021 5:35 am

I agree with your basic skepticism, but models can often be useful.

It’s their blatant misuse, especially claims that they “confirm” something or “prove” something that are highly dubious. Anyway, I was just trying to bring up a connection between human activity and iodine to address BJ above.

My guess is that human atmospheric contribution of iodine is negligible.

December 26, 2021 6:33 pm

If it’s dust from deserts then it’s always been happening. Can’t be blamed on either man or CO2.

On the other hand, it’s a good that CO2 is greening the deserts

Tom Abbott
Reply to  MarkW
December 27, 2021 4:52 am

“If it’s dust from deserts then it’s always been happening.”

That’s what I was thinking.

Clyde Spencer
December 26, 2021 6:43 pm

Let’s avoid adding anthropogenic iodine into the stratosphere!

The assumption seems to be that iodine is associated with generic ‘dust,’ which really relates to particle size, rather than the mineralogy of the ‘dust.’ I would guess that in the Atacama Desert, the ground receives fine particulates of sea salts, which will include iodine. Iodine is not particularly abundant in common rocks. Thus, the geochemical trash heap of Earth, the oceans, seems a likely source.

I can believe him when he says, “… the science is sharper than it was. “I have more questions at the end of the project than at the start,”

Alexy Scherbakoff
Reply to  Clyde Spencer
December 26, 2021 8:56 pm

My link is awaiting moderation? Meanwhile a cut and paste from the website.
Iodine SourcesIodine
No less than 99.6% of the earth’s mass can be accounted for by thirty-two of the chemical elements. The remaining 0.4% is apportioned among sixty-four elements, all of which are present as traces. Iodine is number 61 on this list, making Iodine one of least abundant non-metallic elements in the total composition of the earth.
Although not abundant in quantity, iodine is distributed almost everywhere. It is present in rocks, soils, waters, plants, animal tissues and foodstuffs. Except for a few rare occasions, elemental iodine is not readily found in nature. Iodine is mostly found combined with other elements, such as oxygen, hydrogen or carbon. Due to the ease with which it can accept or donate electrons in its ionic states, it is readily incorporated in inorganic salts or complex organic compounds such as the mammalian hormone thyroxine.
A few substances characteristically contain iodine in relatively large quantities. Natural accumulating organisms are seaweeds, sponges and corals. For industrial purposes, the main sources of Iodine are deposits of minerals, either as solid ore (Caliche) or in underground brines. The iodine in these deposits is chiefly of oceanic origin, transferred to the atmosphere as iodine-rich organic material and as gaseous iodine formed by photochemical oxidation of iodine at the ocean surface.

Tom Abbott
Reply to  Alexy Scherbakoff
December 27, 2021 4:54 am

Thanks for the education.

December 26, 2021 7:30 pm

And this is our fault ?

December 26, 2021 7:31 pm

Is iodine present in all soils? The EPA wants to regulate dust from farming. The EPA might make our air worse.

Reply to  Myron
December 27, 2021 2:12 am

“The EPA might make our air worse.”

The EPA will make our air worse.”

Reply to  Myron
December 27, 2021 2:45 am

not common is aus soils early settlers etc had goitre issues in a big way until they wised up and iodised our salt
now the young ones dont realize the need to buy iodised salt and the issue is returning

Reply to  ozspeaksup
December 27, 2021 3:40 am

It’s worse than that. I recently tried to buy iodised salt at my local supermarket, it now appears to be unavailable in the UK. My local pharmacist told me that iodine compounds are banned here because Iodine is an environmental pollutant.

Alexy Scherbakoff
December 26, 2021 7:54 pm

Doesn’t the d!ckhead know that iodine sublimes? Why is there a question about how iodine dust turns to gas. God help us.

Reply to  Alexy Scherbakoff
December 27, 2021 3:52 am

TIL that mineral forms of iodine can sublimate. I don’t think that this is common knowledge for the overwhelmingly vast majority of people. Maybe you should refrain from using insulting language regarding folks lack of relatively obscure knowledge.

Tom Abbott
Reply to  wermet
December 27, 2021 4:56 am

Good advice.

Alexy Scherbakoff
Reply to  wermet
December 27, 2021 12:38 pm

It’s not necessarily common knowledge, Although it was the first demonstration of sublimation in high school. It was his lack of understanding of iodine that I was commenting on. If you have a study that includes iodine, you should study the properties of iodine and not be too puzzled.
I was having ‘a go’ at him, not everyone else.

Last edited 29 days ago by Alexy Scherbakoff
Reply to  Alexy Scherbakoff
December 30, 2021 2:00 am

it was the first demonstration of sublimation in high school


December 26, 2021 8:30 pm

There is no iodine in sand. Iodate, maybe.
What nonsense.

Alexy Scherbakoff
Reply to  HenryP
December 26, 2021 8:42 pm

Iodate is reduced by sulfite:[1]
6 HSO−
3 + 2 IO−
3 → 2 I− + 6 HSO−4
Iodate oxidizes iodide:
5 I− + IO−
3 + 3 H2SO4 → 3 I2 + 3 H2O + 3 SO2−4
Similarly chlorate oxidizes iodide to iodate:
I− + ClO−
3 → Cl− + IO−3
Excuse the poor wikipedia cut and paste

The basic point I’m trying to make is that elemental iodine is not difficult to make in the atmosphere.
The author seemed to have slept through basic chemistry classes in high school or doesn’t know how to use a search engine on the internet.

Reply to  Alexy Scherbakoff
December 27, 2021 3:33 am

A friend in my geology network reports seeing elemental iodine crystals when he visited the vent of Etna during its quiescent phase.

Pat Frank
Reply to  Philip Mulholland.
December 27, 2021 8:59 am

Sealed bottles of elemental iodine will have I₂ crystals on the underside of the lid from sublimation and recrystallization.

Here‘s a nice video showing iodine sublimation and recrystallization.

But elemental iodine goes directly from solid to gas at room temperature. In the open air, the solid will sublime away. I can’t imagine iodine crystals remaining in a volcanic vent unless there’s a constant re-supply.

December 26, 2021 8:49 pm

So ozone was higher when the Sahara was a green savanna? Won’t that show up in our ice core oxygen isotopes ?

December 26, 2021 8:59 pm

Iodine molehill.

CU Boulder; note to self, make mountain out of iodine molehill.

December 27, 2021 2:23 am

It seems that the Etna volcano is one of the largest know natural point source emitters of Hydrogen Iodide (HI) and Hydrogen Bromide (HBr) on the planet.

Here we report the first measurements of Br and I emissions from Mount Etna: one of the most prominent volcanic point source emitters on earth.

Aiuppa, A., et al., 2005. Emission of bromine and iodine from Mount Etna volcano. Geochemistry, Geophysics, Geosystems, 6(8).

Vent emissions of these halogen volatiles are known to occur in collision arc Andean type volcanoes.

The bromine flux (for Etna) is comparable with that recently estimated for Soufrière Hills volcano, Montserrat (0.35 kt yr−1 Likewise, the iodine flux is similar to those previously measured at arc volcanoes (i.e., White Island, New Zealand, 0.007 kt yr−)

Are there any known reports of the amounts of the ozone damaging halogen volatile HI coming from Mount Erebus in East Antarctica?

Clyde Spencer
Reply to  Philip Mulholland.
December 27, 2021 9:15 am

Who would have thought that there are variations in the amount and type of volcanic emissions and that citing measurements of CO2 from Mt. Etna might not be representative of all volcanoes? /sarc

Clyde Spencer
Reply to  Philip Mulholland.
December 27, 2021 9:18 am

Are there any known reports …

I do remember reading a report many years ago about unusually high concentrations of hydrofluoric acid.

December 27, 2021 2:42 am

yawn really?
how nice
now go get a life..
and these people get paid to come up with this crud?

December 27, 2021 3:29 am

So long CFCs and CO2. This calls for the International Organization for Disastrous Iodine Necrotizing Earth plus the usual Grants sundry wealth transfers and expenses.

Goodbye Greta as Colossal Catastrophism has a new icon-
821757.jpg (600×844) (

Tom Abbott
Reply to  observa
December 27, 2021 4:59 am

“International Organization for Disastrous Iodine Necrotizing Earth”

IODINE, for short.

Ya, gotta love this place! 🙂

Gavin Hardy
December 27, 2021 3:38 am

“Afflicted by studies with small sample sizes, tiny effects, invalid exploratory analyses, and flagrant conflicts of interest, together with an obsession for pursuing fashionable trends of dubious importance, science has taken a turn towards darkness”

Richard Horton, The Lancet

Reply to  Gavin Hardy
December 27, 2021 4:59 am

Maybe he burned his fingers?
This Horton took 12 years to retract Wakefield’s fake autism-vaccine paper. Look at the result!
He took only 12 days to retract the Surgisphere study.

Tom Abbott
Reply to  Gavin Hardy
December 27, 2021 5:00 am

Richard Horton nailed it.

Pat Frank
Reply to  Gavin Hardy
December 27, 2021 9:01 am

Research universities have become criminal enterprises. They produce fake science for real dollars, and knowingly so IMO.

December 27, 2021 3:46 am

Iodine in desert dust destroys ozone

It is all about how you frame the message.

How about this instead:

Natural Iodine in the atmosphere destroys poisonous ozone.

Mike McMillan
Reply to  Philip Mulholland.
December 27, 2021 3:33 pm

That’s kinda like how the life-essential gas carbon dioxide makes a small contribution to beneficial global warming.

Tom Abbott
December 27, 2021 4:49 am

From the article: “There, in the stratosphere, ozone is not a pollutant; rather, it forms a critical “ozone layer” that helps shield the planet from incoming radiation. ”

Well, I’m glad this was mentioned. I feel better now.

December 27, 2021 5:09 am

This is the imperative from Margaret Mead’s 1975 ‘Endangered Atmosphere’ Conference :

¨What we need from scientists are estimates, presented with sufficient conservatism and pausibility but at the same time as free as possible from internal disagreements that can be exploited by political interests, that will allow us to start building a system of artificial but effective warnings, warnings which will parallel the instincts of animals who flee before the hurricane, pile up a larger store of nuts before a severe winter, or of caterpillars who respond to impending climatic changes by growing thicker coats¨

…to start building a system of artificial but effective warnings, warnings which will parallel the instincts of animals…¨

Notice the clearly stated intent : to monkey with us. Usually called Anthropology.

Last edited 29 days ago by bonbon
December 27, 2021 6:08 am

Not mentioned that I can see. Ozone is a GHG. And a considerably more potent one at earthly temperatures than the overhyped Methane as it’s absorbance peak at 10 cm-1 is closer to Earth’s purported emission peak around 16 cm-1 than Methane’s 7.7 or so cm-1. To see the effect, run modtran and set it for “Looking Down”. Then set Trop Ozone to 400000 — the same concentration as CO2 and see the result

December 27, 2021 6:48 am

So this is not actually happening, and yet they are screeching doom&gloom simply to advance their leftarded ideology.

Clyde Spencer
Reply to  2hotel9
December 27, 2021 9:22 am

To justify their appointment and bring in grant money.

December 27, 2021 6:49 am

So, in this corner we have fine desert dust and in that corner we have well-connected lobbyists and the Sierra Club grabbing at federal money. I wonder who will win.

Nick B.
December 27, 2021 6:55 am

Iodine atomic weight is 127 which makes molecular weight of 254. Average molecular weight of air is 29. I think the threat of Iodine is just a distraction from the fact that the bigger destroyer of ozone is hydrogen.

Pat Frank
December 27, 2021 8:35 am

“Iodine” on desert dust is likely to be in its reduced form, iodide (I¯).

Iodide can reduce ozone back down to dioxygen.

O₃ + 2I¯ –> O₂ + I₂ + O²¯

This could well happen on the surface of dust particles, with the production of some metal oxide, which remains attached (adsorbed) to the particle.

This mechanism is consistent with, “iodine was quickly transformed into a gaseous form and ozone dropped to very low levels.

“Gaseous form” is elemental iodine, I₂, which is a gas at room temperature.

By far (and I mean way far) the oceans are the largest source of atmospheric iodine and iodide. It may be that all the desert iodide has an ultimate marine origin. Warning about “anthropogenic iodine” is well into stupidville.

Shanghai Dan
December 27, 2021 9:02 am

See? Don’t you get it now?

Since the Evil Deserts are also Killing Our Planet with their ozone destroying iodine-laden dust, we MUST cover the deserts in solar panels! This way not only do we Save The Earth from the Evil Deserts, we generate all the too-cheap-to-meter electricity we need!

It’s all coming together…

Tombstone Gabby
December 27, 2021 2:56 pm

It would seem that our “scientific researchers” have run out of “known unknowns” that might have an effect on climate, and are now getting into the “unknown unknowns”.

Anything to keep the grants coming.

Last edited 29 days ago by Tombstone Gabby
December 27, 2021 6:46 pm

Let’s see, halogen aerosols carried into the atmosphere by dust destroys ozone air pollution. Sounds like more of an opportunity than an environmental issue. But where’s the info about the height in the atmosphere this occurs other than it coming off the Atacama dessert? Kind of high but no where near the Stratosphere. How easily are the iodine molecules washed out by normal weather before it hits the stratosphere? If it’s it easily washed out you don’t have an ozone depletion issue.
But let’s revisit the original statement, halogen aerosols carried to the atmosphere by dust destroys ozone. Now let’s say that halogen is chloride salts and the dust is ice particles over the Antarctic continent in winter. At the southern pole, it’s so cold that the particles could be carried to the stratosphere in the winter by the polar vortex. Could a natural phenomena using ocean sourced chlorine (rather than CFC’s) be the source of the spring Antarctic ozone hole?

Ian MacCulloch
December 28, 2021 3:22 pm

Missing from this discussion is the role of iodohydrocarbon complexes during normal outgassing from oil and gas reservoirs. Depending on their location the reservoirs may also underly the deserts as described in the article. As an aside, the outgassing of iodine compounds diminishes as the reservoir is depleted. I would suggest the authors look a little further afield

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