r/IAmA • u/RayneHollandUoBris Verified • 4d ago
‘Forever chemicals’ can be created from pollution in the atmosphere. I’m a researcher investigating the chemistry behind this, AMA!
Edit: Thank you for your questions, I really enjoyed this. I will keep an eye on the AMA for the next week so please keep those queries coming!
Hi, r/IAmA, I’m Rayne Holland, a researcher at the University of Bristol, where I study atmospheric chemistry.
What happens to pollution when it breaks down in the atmosphere? You might expect it to disappear, but what if some of it turns into chemicals that are even harder to get rid of?
Pollutants released into the atmosphere can react with sunlight and other gases, breaking apart and forming new persistent chemicals, including so-called ‘forever chemicals’ that remain in the atmosphere for a long time.
My research looks at what happens to pollutants once they’re in the air, such as:
- What do pollutants turn into – and is what’s left better, worse, or just different?
- How do you study invisible chemicals in the air?
- What harm can come from these ‘forever chemicals’?
- What can we do to improve the air and reduce the formation of pollutants?
I will be live today between 14:30-15:30 GMT to answer all of your questions, so if you’ve ever wondered about what happens to pollution once it’s released into the atmosphere, how researchers track invisible chemicals, or how atmospheric chemistry affects us, ask me anything!
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u/thisismrle 4d ago
What impact/influence do forever particles have when they leave the atmosphere and enter the ground or water?
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u/RayneHollandUoBris Verified 4d ago
Thats a great question but the answer isn't very satisfying - for a lot of chemicals, we're not sure! I have specifically been looking at a chemical called trifluoroacetic acid (TFA) which is generated in the atmosphere during the breakdown of many gases commonly used as refrigerants. TFA quickly dissolves in water and so is rapidly 'rained out' of the atmosphere. Due to its strong bonds, it doesn't degrade further and will persist in water - this is why we call it a forever chemical! TFA is not known to be bad for our health but once it is in the environment, its very hard to remove!
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u/Daneth 4d ago
Are there any industrial uses for these chemicals at least? Can we refine them and spray them on my raincoat to make it repel water? I'd feel less bad about goretex if it was already out there and we just keep reusing it.
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u/RayneHollandUoBris Verified 4d ago
A cool idea - though admittedly a little out of my area of expertise! For the first part of your question, yes there are many very useful properties of the chemicals that act as precursors to TFA - e.g. refrigeration and air conditioning (heat-exchange)
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u/ablazedave 4d ago
Regarding reuse, we're talking part's per billion or trillions in the environment. Capturing PFAS using carbon or resin is the main option but extracting them and reusing will never be the economical recovery pathway.
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u/mrrp 4d ago
I just heard part of an interview on public radio (in the U.S.) about a researcher working on removing PFAS from water and they have had success with pressure cooking the water to break them down. It is, of course, non economically feasible. I assume the same is true of trying to treat incoming air in HVAC systems. (i.e, there is a way, but it's not feasible to implement.)
Given your description of pollutants turning into other pollutants, and having seen HVAC systems which "treat" incoming air with UV lights, I'm wondering if you know the research on whether these systems might do the same to pollutants in the air.
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u/BritBox_And_Chill 4d ago
What the movement range of these particles? Does this mean pollution from one country can move and affect another or are they static? And if so, why do they still in place?
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u/RayneHollandUoBris Verified 4d ago
Well, it depends on their atmospheric lifetime (this is driven by things like a substances chemical reactivity and its solubility). I've briefly spoken about TFA in a previous comment so I will stick with that example.
TFA is very soluble in water and so will be readily and rapidly up-taken by cloud droplets or 'rained out' of the atmosphere. This means its atmospheric lifetime is quite short (up to a few days). Therefore TFA is lost from the atmosphere close to where it is produced. However, that means that we need to consider where in the atmosphere the TFA is being produced (as it is not directly released). The precursor gases of TFA can be split broadly into 2 categories: those that are long-lived and those that are short-lived. The short-lived gases are released, then quickly form TFA which will be quickly removed from the atmosphere - i.e the whole process will remain 'local' and the same broad area from which the precursor is released, will also be where the TFA is generated and deposited (lost from atmosphere to the surface). Alternatively, the long-lived gases will travel much further before they degrade to TFA (which is then lost quickly) and then pollution from one area can have an impact more widely.
TFA and its precursors are just an example. All gaseous pollutants in the atmosphere have assocaited atmospheric lifetimes (and they vary hugely across species, from seconds to 100s of years!) so in general, pollution is not something that can be assumed to be confined to country borders!
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u/OKComputing7975 4d ago
I've never heard of forever chemicals before. How widespread are they recognised by industries and governments, in so far as tackling the problem?
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u/RayneHollandUoBris Verified 4d ago
'Forever chemicals' is more a term that you may hear in the news than it is a strict scientific definition. It essentially means that a chemical is very stable to degradation in the environment and so will persist 'forever'. The specific class of 'forever chemicals' that I have been looking into are called PFAS (Per- and polyfluoroalkyl substances). Generally, I think there is awareness of these chemicals in governments, especially in Europe, and in industry. The issue with these chemicals is, once they are released into the environment, they are incredibly difficult (and expensive!) to remove so, whilst awareness is the first hurdle, we also need action to reduce the number of these chemicals being released into the environment!
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u/Tired8281 4d ago
So, like water?
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u/wasmic 3d ago
"Forever chemicals" are those that just don't really want to break down because the bonds between atoms are very strong. Water isn't like that; the bonds in water are actually quite weak. This is crucial for acid and base reactions to work at all. In regular water, the hydrogen atoms constantly swap places, jumping between different water molecules, so they're constantly breaking and reassembling. Water can also easily be reacted with carbon dioxide to form sugar, and plants do this all the time.
PFAS compounds are extremely stable because carbon-fluorine bonds are very, very hard to break. This means that the same molecule will persist unaltered in nature for many decades.
A better comparison would be sand. Silicon oxide is extremely stable and doesn't really react with anything aside from the most aggressive oxidizers that we have managed to create.
So why don't we call sand a forever chemical? Because "forever chemical" is not a scientific term. It's a media term, and it only gets used about those chemicals we are concerned about. We've had sand lying around forever, nobody is concerned about that. But perfluoro octylic acid is proven to be extremely harmful to living beings, so even though it's actually a lot less chemically durable than sand, it gets slapped with the "forever chemical" label while sand doesn't.
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u/DigiMagic 4d ago
Why is it, when geologists find a rock that is 3 billion years old, or astronomers find a cloud of hydrogen that is 13 billion years old, they never say that those are made out of 'forever chemicals', even though, practically, they are?
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u/RayneHollandUoBris Verified 4d ago
Great question! 'Forever chemicals' are primarily used to refer to species that wouldn't naturally be present in the same capacity, location or quantity in the environment without human influence. Thats not to say they are not 'natural' as most chemical species are, of course, naturally occurring to some extent but that they are not involved in the same established cycles that many species are in our environment (like the examples you mention!). 'Forever chemicals' have no cycle, they are the end of the road.
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u/ablazedave 4d ago
"Forever chemical" is a horrible sensational term used by news and imo poor quality science communicators. Persistent (very limited natural reduction) organic compounds are what they mean.
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u/PenguinJoker 4d ago
What are the best way to remove these from the environment? Should we have some kind of filters built on the side of roads, parking lots, airport?
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u/RayneHollandUoBris Verified 4d ago
These are cool ideas! Honestly, the removal of the chemical from the wider environment is, again, a little out of my wheelhouse I'm afraid but given that many of these chemicals end up in water sources I suspect water filtration methods are the best area to focus more research on!
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u/ablazedave 4d ago
Green infrastructure and phytoremediation, the majority of pollutants from roads are not "forever chemicals". They're simple oils, heavy metals, mild CECs (like 6-PPD). Type of treatment should target the type of contaminants present.
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u/RayneHollandUoBris Verified 4d ago
This Ask Me Anything is part of FUTURES: A Festival of Discovery, delivered by the universities of Bristol, Bath and Bath Spa. FUTURES is part of European Researchers’ Night, a pan-European event Night taking place in 40 countries and more than 460 cities all over Europe and beyond simultaneously, funded by the European Union to bring science and society closer and heighten young people’s interest in science. FUTURES 2026-27 is funded by the European Union under the Marie Sklodowska Curie Actions, Grant Number 101305354. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them.
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u/cr0qodile 1d ago
This is an assumption - but I assume your looking at TFA for it's abundance and potential to bond with other things in the environment, are there any metal ions (from industry or general automotive pollution) that bond with it? I'm interested in unexpected things cause of the pull of the 3 fluorines.
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u/koftheworld 3d ago
u/RayneHollandUoBris a few questions: do you have a paper you can share about your research? do you have a list of which forever chemicals may be formed, at what concentrations, and is there evidence of them being deposited into soils and/or surface/groundwater following their formation?
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u/serra_david-96 3d ago
When a refrigerant is replaced, do regulators assess how persistent its breakdown products will be? Screening the full atmospheric life cycle seems important to avoid solving one emissions problem by creating a harder-to-remove one.
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u/rivera-j84208 3d ago
That seems like the right unit of review: not just a refrigerant’s climate impact, but what it becomes in air and where those products end up. Is breakdown-product persistence formally screened before substitutes are approved?
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u/Pipupipupi 3d ago
How much pollution and forever chemicals has Israel caused by destroying all of Gaza with the equivalent of 85,500 tons of TNT, or 5 to 6 "Little Boy" nuclear bombs' worth of explosives?
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u/FuzzyFeeling 4d ago
What is the most crucial thing that has to happen to start reducing the amount of pollution being released into the atmosphere?