Strange metals and our own personal ‘oxidation fields’
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This is a science podcast for May 22nd, 2025. I'm Sarah Crespi. First up on the show, freelance journalist Zach Savitzky joins us to talk about the strange metal state. Physicists are probing the behavior of electrons in these materials, which appear to behave like a thick soup rather than discrete charged particles.

Next, a few years ago, researcher Nora Zanoni came on the show to talk about our personal oxidation fields. These are zones of highly reactive radicals our bodies naturally produce that surround us and interact with nearby chemicals. Now she's back to discuss how our personal fields interact with personal care products like hand lotion and how the interaction between these two things affects the air we breathe indoors.

This week in science, freelance science journalist Zach Zavitsky wrote about condensed matter physicists and their growing understanding of so-called strange metals. Hi, Zach. Welcome to the podcast. Hi, Sarah. Nice to be back. You might have noticed I didn't summarize your story in my intro, and I think it's just beyond my powers. But I am looking forward to talking about this. Can we start with what are strange metals? To understand what strange metals are, I think we have to talk about what metals are.

the canonical understanding of metals and therefore electricity. So when we think about metals, we think about normally a lattice of atoms. Oh, yeah, that's what I think of. Shiny stuff. Right, right. That can move current along it pretty easily. Exactly. Yeah.

We think about electricity or current as electrons that pass through the material. We often think in terms of water metaphors. The electrons are like drops of water that are flowing through this material like a river. And what happens is when these drops of water collide with each other or with the lattice of the material, they cause vibrations. The material, they cause what's called resistance.

And so this heats up the material and we lose some of the energy that would otherwise be carried in the current electricity. And this is why we have to pay our electricity bills every month. There's all this loss along the delivery pipeline. Right. At least for

for now, which we'll get to. So strange metals, it's actually a state that some materials can be in, in which this understanding, this framework that we usually use to think about metals and electricity seems to break down. And this has something to do with the way resistance works in them, right? Right.

And so basically, the resistance in these materials at certain temperatures is so high that if we're thinking about resistance as individual electrons or groups of electrons bouncing into atoms, like the resistivity is so high

that the electrons must be bouncing off of things on distances shorter than there are things to bounce off of. Okay, so there's like way more atoms to hit into it if you just calculate the resistance based on how often electrons are bumping into it. Right, but we know how many atoms are there. Yeah, we do. Yeah, okay. Resistance goes crazy unrelated to the kind of the density of the material. There's something else going on. Right.

Right. That's when you heat them up. But they also do something weird when you cool them down. The real reason why we care about strange metals is because they're intimately connected to another state that these same materials can be in called superconductivity or superconductors. Now, we've known about superconductors for a long time, over 100 years. It's this wonderful, magical property of certain materials where when you cool them down to very low temperatures...

Basically, the river of electrons flows without any resistance whatsoever. In theory, you can have materials which transport electricity from the power plant to your house and back without losing any energy to heat.

which, as you can imagine, would be super useful for societal and environmental purposes. Everything would be incredibly efficient. We could distribute electricity as far as we wanted from the solar fields of Africa to my house in Indiana. It would just be very futuristic if this were in practice. And not to mention the fact that they also have other very crazy magical properties, such as magnetic levitation. These materials, when you put them on top of normal metals, they float.

And you can push them above tracks and they just, they hover there. So you could have trains made out of these. Frictionless travel as well. Exactly. Without any friction. Let's stop the fun train there and say what the holdup is with superconductivity. Why are we not doing this now? So when we originally found the first superconductors, the transformation to this state of superconductivity happened at really, really, really low temperatures. It

It happens at about four degrees Celsius above absolute zero, which is the coldest possible temperature in the universe. Yeah. So we're now like minus 270 something Celsius, right? Right. Yes. Over the years, physicists have found superconductors at higher and higher temperatures, but they still need to be quite, quite cold in order for this to happen. Yeah. And we're not going to do that for moving electricity around the planet or moving a train. They need to be prohibitively cold for this to make sense as a useful technology.

or prohibitively high pressures. Right now, it doesn't make sense to use these as part of our infrastructure. Yes. Let's bring in superconductors and strange metals. How do they relate to each other? So the dream of condensed matter physicists, one of the big ones, is to find superconductivity in ambient conditions. So at room temperature, at more or less room pressure.

Physicists have come a long way in understanding how superconductivity works in certain cases. So what's called conventional superconductivity. In these really, really cold materials, we actually know how this superconductivity happens. We don't know how it happens at higher temperatures, even at the higher temperatures that we've seen already. These are called unconventional or high temperature superconductors. Basically, there are some ideas floating around, but physicists do not

understand how this property is happening because the mechanism responsible for superconductivity in these very cold materials simply wouldn't work at these higher temperatures. Now, some physicists think that the key to figuring out how this works, there was a clue in the original experiments that showed us this unconventional superconductivity, which is that when you heat these superconductors up a bit more above what's called their critical temperature below which they drop into superconductivity, if you heat them up

above that, then they enter this strange metal phase in which the resistivity is much higher than we would expect. Extra bad at moving electrons around if you get them too hot. There's a slight distinction between these, but there's what are called strange metals and there's what are called bad metals. So they actually use this terminology as well. I love it. These unusual superconductors may have something in common with what's going on with strange metals at high temperature. Right. That's the thought. And we know superconductors

Strange metals, when they go below a certain temperature, do act like superconductors. But they're not... When the strange metals act like superconductors, they still really have to be really cold? There's always this critical temperature below which the resistivity instantly drops to zero. And strange metals undergo this same transition. It's just...

below this critical temperature, they are superconductors. And above the critical temperature, they are, rather than normal metals, they are strange metals. And where is the critical temperature for the strange metals that people have looked at? It's not room temperature, right? No, no, it's far below room temperature.

Most importantly is that whatever's going on with the strange metals might give us insight into the superconductors that we all are dreaming of. These room temperature superconductors that don't behave like kind of the traditional ones discovered all the way back in 1911. Right. This is one of the big motivators for people to figure out what's happening in strange metals. And beyond that, these physicists also care because the strange metals, this outlier class seems to hint at

cracks in the general understanding that we have of how electricity works, which for physicists set aside the fact that this could have a useful practical application one day. This is something that's worth pursuing for them. Absolutely. I mean, I feel like electricity was solved a long time ago. So I'm excited that there's no question. Can we just talk a little bit about what makes a strange metal? Like what kind of materials it is? Is it like all the same atoms or is there some kind of like

Crystal, that's important for it. What do we know? This is something that's really interesting as well, which is that over the past couple of years, they've found that this behavior of materials happens in a much broader class than they originally expected. So originally we found strata

strange metal behavior in these copper-based materials called cuprates, which is where we originally found the high-temperature superconductors as well. But now physicists have seen this strange behavior happening in over a dozen different materials that are all over the board. There's one that's made from ytterbium rhodium silicon. There's one that is sheets of graphene that are twisted at certain angles. These are

materials that seemingly have nothing to do with one another, which is hinting at this being a very deep sort of universal behavior. Let's talk about some of the experiments people are doing. You visited these labs and there's some pretty interesting setups that they need to kind of investigate what's going on with electrons in strange metals. Physicists have been hellbent on trying to figure out what's going on inside of these materials. And just a couple of years ago, there was a super interesting experiment that

conducted by some researchers at Rice University and some at the Vienna University of Technology. This is called a shot noise experiment. What they're doing is they're basically taking a wire made of strange metals and they're transporting electricity through it. So they're running current through the wire. And then they're listening to the noise

of the electrons passing through the wire. So if you do this in the normal material, you expect a certain characteristic noise that's associated with the individual electrons coming through the wire. You can think about sitting in your car and listening to the rain, to come back to this water metaphor. If you're listening to the pitter-patter on the roof as the rain comes down, you can, from this noise that you're listening to, figure out the size of the raindrops and how frequently they're coming.

So if you know that, for instance, it's going to rain one inch over the next hour, and then you listen to this noise, you can figure out how big the raindrops were and how frequent. Now, in strange metals, when they listen to this noise, they don't hear the pitter-patter, pitter-patter that you would expect from the rain. They hear this perfectly fine mist. It's almost as though it's one continuous sheet of rain without any individual water droplets. So more than fog, it is just...

Just a blob somehow. Exactly. One of the tricky parts about this field is that they don't really know how to talk about this. So they often use terms like quantum soup to talk about it. To think about it as undifferentiatable mass of electrons is really hard to, at least for me, and I'm sure for a lot of other people, hard to wrap your head around. Like, how can they move? But they're also just kind of like goo.

So that's what it sounds like when you listen to the wire and it's a strange metal? Yeah, exactly. Oh, so interesting. So the other thing they're doing that you described in your experimental section is they're trying to count entanglement. How many electrons are entangled? How would you do that? And is that kind of an important component of the theory here that people are testing? If you have a material in which charge

charge is being transported not by individual particles like we're used to, like electrons, but as one sort of cohesive quantum soup. The natural assumption for some physicists is to think about entanglement, which is this strange property within quantum mechanics in which you can have the properties of different particles be linked even when they're at distances far apart. So what this effectively does is it sort of spreads out

the particle between different places. This idea has been around for a number of years. People have talked about the strange metal having a very high level of entanglement, which means that many particles or electrons within this material must be entangled with each other simultaneously. So they're contributing to the flow of electricity, but they're not themselves flowing? They're not themselves really there in any distinct way. Okay. It's like

They have no central identity in the sense that you can never point and say there's definitely an electron here. And some experiments are showing that you can't even do a reliable measurement of how many electrons there are in the system at any given point in time. Okay, but that is what they're trying to do. They're trying to count how many are entangled in the material. They're trying to figure out a window into this entanglement and...

And some experimentalists and theorists just in the past year actually have figured out how to probe entanglement in these strange metals. They do what are called scattering experiments. So they're basically like if you think of the charge as this quantum soup, you can do sort of like X-ray experiments where you shoot particles at the soup and you see how those particles scatter off of things. What's taking a deflection and what's deflecting it? From those experiments.

they are able to do some fancy mathematical moves to figure out, indirectly quantify the entanglement in the system that must be there. This is a proposal that's only been around for a couple of years. I think maybe a decade ago, it was first in any materials whatsoever. And just in the past year, this has been done in strange metals for the first time. I'll try to explain to you more of how I think about this experiment, but with the caveat that it's a big simplification and also it's still pretty out there. But

Someone described it to me as you can imagine these experiments are like shooting cannonballs at the building.

You're looking at the way that the cannonball reflects, bounces off of it, or slightly changes its trajectory as it passes through to figure out properties of the building itself. When you hit the building with the ball, you will hear it, the noise it makes, it'll happen at the characteristic note at what's called the resonance frequency of this building. So maybe it'll play a C note or something. And if the different floors of the building are entangled with one another, the note that

the building plays when you hit it with the cannonball is different than it would be otherwise. It's a lot more violent than I thought you would go. I thought we would go back to water, but I'm digging the cannonball. It's sort of like you can hear a superposition or an overlap of the different resonance frequencies of different floors at the same time. Someone described it as like an orchestra playing when all of the instruments are being tuned, where it's just this like cacophony. Cacophony, yeah. Right, yeah. So that's...

A metaphorical way of describing detecting entanglement of electrons. Do you come away, do the researchers come away from these experiments saying nine? There's nine entangled electrons? Yes, actually, they say nine. Good guess. But what does that mean if there's nine entangled electrons? A caveat here is that these calculations are very difficult to do and they're very new, as I mentioned. And so

When these physicists did these calculations for the first time, this is an extremely conservative estimate. They tell me that like they are very certain from their calculations that at least nine particles in this material, nine electrons must be quantum mechanically entangled with one another. They suspect that it's actually many, many more electrons than this at the same time. But even still just showing that there is this, it's called multi-partite entanglement.

entanglement, so entanglement between multiple different electrons at the same time, not just a pair of them, is noteworthy. And it shows that entanglement is clearly a sort of a central aspect to this behavior. Meaning that entanglement is not happening in regular flow of electrons in a non-strange metal? At the very least, we can assume that it's not happening and the calculations still come out correct. The general framework for how electricity works in normal materials is

doesn't consider this entanglement. It doesn't actually consider any interactions between electrons. And the math works out. That works out for like copper. If you are just thinking about electrons passing through a copper wire, it's okay to just sort of ignore the interactions between electrons. If we care about special materials,

materials, which physicists do. And if we want to improve our materials, then we do care about these interactions. For instance, with superconductivity, you need to account for interactions between electrons. And obviously, electrons are interacting because they're negatively charged. They're going to repel one another. It's an okay simplification to make for copper. It's not an okay simplification to make for superconductors. But what they figured out is that for superconductors,

they can simplify this interaction by just treating a whole clump of electrons as one bigger, heavier particle, which they call a quasi-particle. Okay. And when they do that, the math still works out.

But now we're kind of stepping into another place where we're saying, what if it's a bunch of entangled electrons in a soupy blob moving through? That's what strange metals are doing. We're reaching the point where even this quasi-particle picture is breaking down, where clearly we need to be thinking even more about electron interactions in a fundamentally different way than we've been doing before.

So we talked about the shot noise and we talked about detecting entanglement or counting entanglement. Is there another way that people are kind of trying to untangle this? And the scattering thing, which I mentioned as well. Oh, that was very cool. Yeah. That's what the experimentalists are doing. And we kind of have to go to the other side of the street where the theorists are working the numbers and working the way of thinking about this. So what have they come up with for what might be happening here at this micro scale or quantum scale?

This has been a really challenging problem for theorists. One physicist told me that this is the hardest problem that we have in condensed matter physics. And for a while, that's sort of why people hadn't been making more progress on it because they had just gone for other questions because we don't really know where to start with this strange mental. However, in recent years, especially because of this great experimental progress that's happened, theorists have more to grasp onto. And so they're starting to put forth ideas of what might be going on.

And just in the past couple of years, there's been a bit more convergence in their ideas from the people who I've spoken to. Most of them seem to be on the same page that we cannot be thinking about electricity in terms of quasi particles when it comes to these strange metals and that the entanglement between electrons is important and that we need to be thinking about this quantum soup of electrons as the thing that's carrying charge. So that's sort of the common ground that they've come to. However, we've

what it takes to create this quantum soup, like the ingredients for this soup, are very controversial still. And people have ideas that are sort of all over the map. Oh, what else is in the soup besides electrons? Or is it the kind of electrons or who's giving up electrons? That's important. It's sort of like, how do you coax electrons to create this highly entangled soup? What are the microscopic details that encourage them to go into this state like this? Which

is clearly not a comfortable state for them to be in because the resistivity is so high. So what's actually going on underneath the hood? Okay, what else should we say about the theories here? I can go into some details about them, but honestly, it's hard to wrap your head around, especially without seeing images of things. I do want to point everybody to the graphics that came out with this story. I just think they really help kind of anchor what we're talking about with

with words only, even though, of course, this is not as visible to the naked eye. I just think the visual metaphors are really helpful. So go check that out. Agreed. Yeah, the team did a great job on this. So we've talked about the experiments that people are doing and the theories that are starting to come out of this, you know, and how does that help us with the superconducting problem? How does that kind of get us closer to room temperature superconducting? It's not exactly clear. We're not yet to the point of fully understanding what's happening in strange metals.

And we're even farther from understanding how that connects to high temperature superconductivity. However, these theorists seem pretty convinced that we need to figure out the strange metal state in order to figure out the superconductor state. The progress that they're making on the strange metal will certainly be helpful for creating this world changing new class of materials. So one theorist suggested to me that perhaps what's going on in the high temperature superconductors is

fundamentally very similar to what's happening in the strange metals in that maybe it is some sort of quantum soup that's also responsible for the superconducting behavior. In conventional superconductors, the way that we understand how this is working is that

electrons will trigger a wave, a sound wave through this material that links two electrons together into a quasiparticle. These paired electrons can ride through the material without resistance. Now, we know that at higher temperatures for these unconventional superconductors, it can't be these vibrations that are causing this pairing to happen for the quasiparticles. The question for a long time is how do you form the glue

for these paired electrons? What could it be that's gluing these electrons together? One theorist for this story suggested to me that perhaps we've been thinking about this all wrong. Maybe we don't need a glue if the whole thing is a soup. The whole thing is glue. Right. Yeah, that's still a long cry from building materials that will allow you to stop paying your electricity bill, but maybe it's a step along the way. Thanks, Zach. You have given me a lot to think about.

Thank you, Sarah. Happy thinking. Zach Savitsky is a science journalist specializing in the physical sciences. You can find a link to the story we discussed and some very helpful diagrams at science.org slash podcast. Stay tuned for a conversation with Nora Zanoni about how our skin makes reactive particles that can change indoor air chemistry.

For those of us who spend the bulk of our time indoors, like around 90% of the time, if you're an average American or European, the indoor air quality might actually be more important than the outdoor air quality. We're surrounded by chemistry from our household items, from our own bodies, with big changes sweeping through the space during cooking or cleaning. A few years ago, we had a researcher come on the show and talk about our own personal oxygenation.

oxidation fields. This is a zone around us created by chemicals emitted by our bodies reacting with ozone. Now, Nora Zanoni is back.

to discuss the interaction of this personal field with personal care products. For example, how does applying lotion affect your ability to form this field? Hi, Nora. Welcome back to the show. Hi, Sarah. Thank you for inviting today. Thank you. Sure. To revisit our last interview, you detected this oxidation field around people. It comes from a reaction between chemicals on the skin or in the breath and ozone. What do we know about the effects of this personal field?

What does it do? Is it good? Is it bad? Saying it's a field makes it seem like it maybe shields you from something or protects you. Is that what it does?

If it's good or bad, we do not really know what is the net effect of this because what happens is that this OH radical can initiate some reactions indoors which are less selective than the reactions that ozone can initiate. We know that ozone can infiltrate from outdoors to indoors and can react with many chemicals present indoors. And now we have also OH, which is also reacting indoors with many chemicals.

That means that some of the chemicals that are emitted indoor will be transformed to some products. The overall toxicity of these products, we do not know that yet. What we know is that the primary compounds that are emitted indoors will be reactant and will be transformed into something else. So if the primary compounds were bad to us, then having more oxidants in the air will help to

clean the indoor air. But we do not know the toxicity of these whole products that can be generated. So this is kind of part of a big project to figure out all this chemistry in our spaces where we live and how, you know, things coming inside are affecting it and how all the chemicals we use in our daily life are affecting it and how our own bodies serve as

sinks and sources for chemistry in the air. But because this oxidative field requires a contribution from us, from our skin, it can change if we're wearing perfume or lotion.

Let's talk about how you tested this. Can you take us to the chamber where these experiments took place? Yes, indeed. This was a big project that started in 2019, first with the discovery of the human oxidation field, and then there was a follow-up experiment. Measurements were run in this facility at the Technical University of Denmark. This is a stainless steel

chamber, which is about 22 square meters of volume. And the volunteers were sitting in the chamber. So we had four young adults that were participating to these experiments. In the second part of this project, what we wanted to study was really the different conditions that are actually present in our real life and in real indoor environments. And one of these is what happens when people wear fragrances or body lotions.

And the experiment started first without having any ozone. Basically, volunteers were exposed to clean air. There was outdoor air filtered for particles, VOCs and ozone. We were testing conditions without any ozone present.

because we know that ozone can play an important role indeed in indoor chemistry. And then the second part of the experiment, we injected ozone inside and we were testing how ozone was reacting with the chemical presence in the room. So what did you, were you using like macros?

Mass spectrometry. Yeah, yeah. We were using several techniques. They're all very advanced from mass spectrometry and gas chromatography for measuring volatile organic compounds. But then we were also measuring the OH reactivity. This is a measure that can be done directly. And in that case, it was also done by using mass spectrometry with a method called comparative reactivity method. And with this instrument, we can measure the total loss rate of the hydroxyl radical.

Okay. OH radical, hydroxyl radical. Same thing. It's got, it's a radical and it's going to interact with a bunch of different stuff as soon as it runs in. Yeah. Oh,

Okay, so let's talk about the fragrance first. You chose CK1 from Calvin Klein. Yeah. Which I think is, I think a lot of people will know that. That one's been around for a long time. I remember it from high school, people wearing it and being very popular. Yeah, because we wanted something that was popular, commercially easy to find, and that was worn from many people. There was also unisex, so worn from many people.

and women. Overall, simple, let's say. Of course, with the simplicity, we can't tell how much it's simple in comparison with other perfumes. But we wanted to have some citrus fragrances. Like a lemon or a backgammon? Yeah, this is something quite common in fragrances. And that's an indication of the presence of limonene, which is a very reactive compound. So we were searching for something similar to that. And we thought that that could have been a good choice. Okay.

So what happens when a person puts this fragrance on and goes into your super clean chamber with or without ozone? What do you see? First, volunteers were wearing the fragrance before entering the chamber, let's say five minutes before they could enter.

And the effect that we measure after they entered was not so significant. I mean, we saw some differences, but about 10% of what we measured without the fragrance. So we wanted to see more of that. And so we asked volunteers to spray a bit of the fragrance while they were sitting in the chamber. And in that case, we saw a lot happening. This is because, of course, fragrances composition are different.

variable, but all of them are diluted in some solvents. For fragrances, the main solvent used is ethanol. It was enough to really see huge spikes in the instruments. We had a very large concentration of ethanol, also high concentrations of terpenes, other rose compounds.

And the overall effect was totally dominated by the presence of the solvent. So while we were expecting that the fragrance itself would have played a role by reacting with ozone because these molecules are very reactive. So these compounds have carbon-carbon double bonds. So we would have expected a lot of OH coming out from these reactions.

This was not actually the case because the overall net effect was really dominated by the solvent. So what you can take away from the fragrance experiment is that ethanol is kind of the predominant chemical that affects the field or affects the presence of OH. And then also that's probably going to happen no matter what kind of fragrance you're talking about, right? Because they all have this kind of solvent as well as whatever the odor molecules are.

Yeah, basically any fragrance contains ethanol in large amounts. If you have a lot of ethanol involved, what does that do to your oxidative field? That will be suppressed because we will normally still form the oxidation field from exposure to ozone. But by introducing the chemicals from the fragrance, the OH field that we produce will be immediately suppressed. So the overall effect is to have a decrease in concentration of OH when we use a fragrance.

And that's the net effect of the fragrance itself. So let's talk about what happened with the lotion. Now in this, you're doing a similar thing where the person is wearing it, there's ozone or no ozone. How did that affect the oxidative feel of the people? Yeah, that was very interesting as well. The lotion that we tested was fragrance-free, so we could only see the chemicals of the lotions.

So in that case, our lotion was containing linoleic acid. And linoleic acid is the component of many kinds of ingredients that can be found in lotions. For example, in this lotion that we tested, there was shea butter, rapeseed oil. And then we had jojoba oil also. Different ingredients that was containing linoleic acid.

And actually the amount of linoleic acid can change in these different ingredients. But the overall effect is to introduce this component on our skin. If we compare that with our natural lipid, that would be, I mean, the most known one and the most studied one is squalene. That constitutes about 20%, I would say, in composition of our skin lipids.

If we remember from the previous paper, we checked the oxidation products of squalene. One of these products, like 6-MHO, was the most efficient in producing the human oxidation field. Okay. I just want to point out that someone once gave me a present and it was squalene that you just put on your skin.

But that's very nice. That's very nice. So we can actually naturally form squalene. And also the amount of squalene that we have on our skin depends on different factors. It depends on gender. It depends on age. So the more we are aging, the less we are producing squalene. So what happens if you swamp out the squalene with

all this other stuff in your lotion. If you put it all over your skin, squalene is not dominating. If we look at the chemical structure of squalene and the chemical structure, for example, of linoleic acid, we see that squalene has more carbon-carbon double bonds.

has a six. That's a triterpene hydrocarbon as a kind of molecule. While the linoleic acid, this molecule has only two carbon-carbon double bonds. So what happens is that if ozone reacts with the skin surface, then it will find less carbon-carbon double bonds available for reactions. The

the use of a lotion on our skin will kind of impede the availability of carbon-carbon double bonds to react with ozone. That means that at the end, we will have less production of 6-MHO, which was the most efficient molecule we saw in producing the OH field. And that's one of the effects that we saw. The other effect that we saw is that the lotion itself can emit some chemicals. For example, the one that we saw in the lotion we used is phenoxyethanol,

This is a molecule that we discovered to be present in many different lotions because it's a preservative of the lotion. So it's quite representative of what we studied for real world, real use. So the presence of this molecule that is emitted from our skin will have the effect of reacting with OH.

So we have two effects overall. One effect is less OH is produced because less carbon-carbon double bonds are available to react with ozone. And on the other side, some reactive molecules to OH are released that will reduce the concentration of OH. So the overall effect in this case is still a suppression of the OH field. Yeah.

Now, if we find out somehow that the OH field is good for us, and it's something we want to take care of, could we design perfumes, fragrances, and lotions that would help it? That's a complicated question, I think, because it's really depending on the indoor environment where we are and the fragrance itself or the lotion itself. Because definitely the OH field is helping transforming the primary release chemicals.

but still depends on what kind of chemicals are in that environment. - Right, so is the ultimate goal of this research to kind of figure out what's doing the most in our environment?

What are you hoping to kind of understand about the indoor environment with this work? So with this work, the aim was really to see since we as consumers use a lot of fragrances and use a lot of personal care products, and we saw also that personal care products have an effect to outdoor chemistry. We wanted to test how these can influence the indoor air chemistry and indoor air environment, specifically in terms of OH production and in terms of

OH reactivity. So this human oxidation field that we produce naturally, how is this influenced by other inputs that we have in real world scenarios like real indoors? Yeah. But we can't take away from this. Stop lotioning, stop fragrancing, stop bathing. It's really just like we need to know more about how our chemistry and the indoor chemistry interact and what personal products do in the interface there. Yeah.

Okay, so we're not recommending people stop using lotion. Not yet, not yet. But I think that we are going, well, that's maybe an idea, but I think we are going towards a less scented world, like in terms of also if we as consumers, we want to buy some personal care products. We see more on market that do not contain fragrances, for example, to avoid irritation and other kind of health issues.

Yeah. And it does seem like you could interpret the personal oxidation field as something that would stand between you and whatever chemicals in the environment and kind of say, OK, we're going to tackle these chemicals somehow with their oxidation reactions. But.

But it's really going to depend on what's out there, whether that's good for you or bad for you. Yeah, indeed. So what we're studying here is what happens to the indoor air chemistry. But in terms of health effects, of course, we need to know more. And one critical factor that it's still not well understood is the toxicity of all these chemicals that can be found indoors.

Yeah, that's even harder to do than finding out what all the molecules are inside of a space. It's what do they do to your body and how much does it matter over time and how much of it do you have to interact with for it to actually affect your health? There's just...

It's an incredibly complex problem. Yeah, it is. It is. Have you measured your own personal oxidation field? I wanted to. I wanted to. I tried once. What happened? There was another kind of experiment, actually. But yes, I was curious to see what was what were my emissions. We started to do also random experiments just to see what it was very funny. It was very fun. What did you learn about yourself?

The time that I tested myself, actually, I was with some blankets and some furniture that were emitting a lot. So it was actually not... So you can't beat a couch. Yes. So it was a bit difficult experiment to interpret. It didn't really work. I mean, because there were many more emissions we were measuring. Super interesting, though, to think about like how to pick out a person versus a couch and a blanket.

Could you see which is which from the field? Definitely, you can. That's really cool. Thanks, Nora. It's great to have you back again. Thanks a lot, Sarah. And hope to see and talk to you again. Nora Zanoni is currently a postdoctoral researcher at the Institute of Atmospheric Sciences and Climate at the National Research Council in Italy. The work for this paper was done when she was a postdoc scientist at the Max Planck Institute for Chemistry.

You can find a link to the science advances paper we discussed at science.org slash podcast.

And that concludes this edition of the Science Podcast. If you have any comments or suggestions, write to us at sciencepodcast at aaaas.org. To find us on podcasting apps, search for Science Magazine or listen on our website, science.org slash podcast. This show was edited by me, Sarah Crespi, and Kevin McLean. We had production help from Podigy. Our music is by Jeffrey Cook and Wenkoy Wen.

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