Science Friday - The Physics Of Figure Skating, Aerosols, Volatile Organic Compounds. Feb 16, 2018, Part 2

Episode Date: February 16, 2018

While oohing and ahhing at the powerful leaps and nimble spins on the ice at the Olympics, you may not realize you’re watching physics in action. Each jump requires a careful balance of matching the time in air to the speed and number of rotations.  From spray can to ocean spray, it's time to talk about aerosols. They do play a role in climate change, but not the one you might think.  There's a new urban air polluter on the block. Volatile organic compounds like wall paints and cleaning agents are becoming our cities' biggest sources of air pollution.  Could UV light zap the flu bug? Scientists are looking into a way to kill the bug even before it has a chance to get into your system, and one type of UV light could be used to disable proteins in the flu virus.  Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

This is Science Friday. I'm Ira Flato. A bit later in the hour, common household products causing outdoor air pollution. But first, it is impossible to watch the performances in the Winter Olympic Games, the back-to-back 1440s on the snowboarding half-pipe, the quadruple lutses and layback and camel spins on the skating ice, without wondering, how the heck do they do that? Yeah, well, naturally, being a science show, our first instinct was to call an expert in biomic, to talk Olympic laws of motion. Deborah King is that expert. She's professor in the Department of Exercise and Sports Sciences at Ithaca College in New York.

Welcome to Science Friday. Thank you. Let me tell my listeners that if they've seen a stunt that they want you to decode, give us a call. 844-724-825-8-4-4-Sy-Talk or tweet us at SciFri. Dr. King, have you been watching a lot of the skating or do you like? What event do you like the most? Oh, that's a tough call. I like them all. I watch a lot of alpine skiing. I watch the figure skating. I love the bobsledged skeleton and luge.

Ski jumping, aerial, snowboard, you name it. Snow, ice, gravity. It's all fun. You do live up there where it's kind of snowy in Ithaca. So I can imagine why you do that. All right, let's break down, let's go to the skate jumps, okay? From a physics perspective, what's happening in those fancy. skate jumps? Sure, there's a lot going on in a very short period of time. The jumps take less than a second, and the skaters need to go off the ice, jump up in the air. They jump about two feet in the air. If you're watching the guys do their quadlutses. They spin around. They can easily reach rotation speeds above six revolutions per second, and then they need to land without falling. So there's a lot of physics going on with projectile motion and conservation of angular momentum that sort of govern what they can do

in the air. So it's actually a trade-off because if you want to spin and you want to jump high, you're going to suck off some of the energy from each motion. You have to decide how much, right? Absolutely. So they're coming into the takeoff and they need to push off the ice and if they put all their

effort into jumping really high, they're not going to get that angular momentum or rotational resource to spin fast in the air. Or if they really crank it around and go for spinning really fast, they might not push hard enough and go high and it's going to be a balancing act because when it comes down to it, they need to finish their four revolutions right when their foot's contacting the ground so they can glide out and skate into

their next skill. Why do we see a difference in the number of spins, the men and the women skaters can pull off? Sure, a lot of that's going to have to do with body size, so the women tend to be smaller. They generally aren't going to jump as high on average. There can be some women who jump higher, but on average, if they're not jumping as high, they're not in the air as long, so they would have to spin a whole lot faster than the guys would to get around four revolutions. and while they're smaller, it's a little easier for them to spin fast, but that spin initiates when they're on the ice. So when they come off the ice, if they don't have more angular momentum off the ice,

the body size is not going to get them spinning enough faster to make up that far revolutions. So generally it's really going to come down to their size levels. And you talk about angular momentum. That is so important here. What is that? That's a great question. So angular momentum, it's your potential to rotate. It's sort of like a rotational resource.

So it's something you have to push against something to get some momentum to rotate. And then once they're in the air, they can no longer push against the ice. They're stuck with the amount of anger momentum they have. So they only have a certain amount of potential to rotate. But what's really cool is even though they have a set amount of momentum, they can still rotate faster if they want to.

And they do that by changing their body size. Well, so they pull their arms in when they want to go faster. Exactly. The same thing you see them do on the ice where they start with their arms sort of wide, they get to push off the ice, the arms are really wide out from their body, and they pull them and they go really fast.

They do that in the air, too. When they come off the ice, their arms are a little more out from their body, so it's the leg that they're not jumping off of, and then they snap into that rotating position right when they get in the air and the rotation speeds up really fast, and they hold that all the way before they land.

So knowing that that little bit we know about physics, compare snowboarding to ice skating. Are there any similarities in the physics going on there? Absolutely. There's a lot of similarity. They get their vertical velocity for going up into the air differently. They don't have to push off the flat ice surface, but they need to build up speed. If we're talking about the half pipe, coming down one side of the half pipe, crossing over the bottom, the half pipe and going up the other, that's where they get their speed. And that speed they come off the lip or the rim of the half pipe with will determine how high they go. The longer, the higher they go, the longer than the air, the more rotations they can do. And the other thing you see them do as they're coming off, Right before they come off the rim or the lip, you'll see they'll turn their upper body as they're creating a torque against the ice or the snow, and that's getting their angular momentum. So then once they're up in the air, you see them do the same types of things. They move their body position so they can rotate around and get their 1440 done, 1080, whichever skill they're doing. Oh, well, they can do what we can.

Yeah, I can't do it. Exactly. That's why I'm sitting here and there over here. I'd like to bring on another guest now to talk about some of the forces on the skaters' bodies and the way blood is forced through the bodies as they do some of these performances. David Wang, Clinical Director of Elite Sports Medicine at Connecticut Children's Medical Center. Welcome to Science Friday. Hello, how you doing?

Now, I know that you've studied the forces involved in figure skaters spinning. Does a spin subject to a lot of g-forces? Well, it certainly does. the whole body is subjected to forces, and it depends on the position in the spin, but yes, there are certain spins, such as a layback spin, where a significant amount of forces sort of felt by the head. And as you mentioned before, we have the forces, plus we have blood moving through the vessels and being centrifuged out to create a multitude of symptoms.

Is it dangerous moving all that blood and all the forces around? in the head? Well, typically not. I think that anything done in an extreme, of course, can cause some problems. If you were to look at the figure skaters when they finish a spin, such as a layback spin, you'll often see a little patechiae, or little tiny broken blood vessels on their forehead. Some people actually bleed out of the nose, and I've seen the eyes get little sub-conjunct tibal hemorrhages, little blood in the white part of their eyes, all from basically having the blood forced out to their head. And our bodies are not well adapted to handling what we call a negative G force.

The regular G force that we feel is the one where gravity pulls us down that we're used to and we've adapted to. But in the spin, you get a negative G force where you're actually going the other direction. So our bodies aren't as well adapted to that, so they don't tolerate it as well. Here's a tweet from Luis who says, please answer a question that has this house full of physicists stumped. Why do the male half-pipe snowboarders, half-pipe snowboarders, get so much more air than the women, even when the people are about the same size? Deborah, David?

I'm going to, I can take that one, David. You can pipe in if you want. I think we're talking mostly about momentum here, and there's a difference in the body mass of the two skaters. I mean, not all of them. them, but a lot of the guys have a bigger body mass, and so they're going to build up more momentum, so then they can go higher off the edge. And some of it will also be the line they take into the half pipe. So the more directly you're going to go straight down the side of the half pipe, you're going to be able to build up more speed than if you go a little diagonally down it.

Let's talk about the back to skating. What kind of forces are acting on the skaters when they land back on the ice? It got to be incredible, and it's a hard surface. isn't it, Deborah? Oh, absolutely. So the ice is put down on concrete. They're wearing a steel blade on a hard leather-sulled boot. The best measures we have of the forces when they land are easily five times their body weight. They could be a little higher. And if you just do some simple math, if you take 130-pound skater, that's 650 pounds of force that they're landing on one leg, jump after jump after jump. And they're doing this in practice, too. So, I mean, they're... Oh, absolutely. They might do 60, 100 jumps a day in practice.

So your body parts are going to be your knees or your ankles? What's taking the brunt? Anything probably from the hips down, but you see a lot of problems down at the foot and absolutely the knees as well. So foot and knees probably are your number one body parts. When we measured it, it was impressive as the amount that actually gets into the hips as well, because the boot is relatively rigid so you don't get as much ankle motion as you'd like. So you have to transmit that force up, and so the knees is for sure. and the hips get a lot. And in fact, if you sort of look at sort of retired skaters,

you'll see that the vast majority have had hip surgery. And not only that, but, you know, I'm wondering two things. One, why don't they get so dizzy? I mean, David, why they spin around? They're still not. They do get dizzy. They do, but they can control it? Yeah, they have a ways of, there's certainly they adapt somewhat to it,

but they also, and again, Debra can chime in at any point in time, but there are the sequences that follow the spin sequence where it's a little bit of recovery time is built in there. So maybe a footwork sequence or something before you go back into the jumps and the other parts, the other elements of the program. A tweet from Hal who says, would using weighted gloves help skaters increase their angular momentum? I guess what he's saying is when you hands out, you bring them back in? You put more weight in them? Deborah, what do you think? That's an excellent question, and that's actually been studied a little bit. So the answer is, yes, you can generate more angular momentum,

and then when you snap into your rotating position, you can pick up a heck of a lot of speed. The skaters who have tried it, it feels very different. There's been research studies done in this, feels very different, so it really changes the timing of the jump, so it's not so easy that all of a sudden you can put weighted gloves on, and all of a sudden you'll be doing a quintuple jump instead of a quadruple jump because you're rotating faster.

It really throws off the timing of the jump. and the skaters generally adapt just by they have more angle momentum so they don't get as tight and they keep sort of the same rotation speed. So they're not cheating. Yeah, and it would be difficult. One of the things that's not appreciated about these skaters is that essentially each program is like running a mile. And the amount of endurance that it takes is tremendous. So these people are in incredibly good shape.

So you'd start adding weights to them when they're doing that program, and I think they're going to pay for it. Is it legal? I actually don't know the rules on that. I have not seen a rule against it, but I don't know, Dave. Do you have any idea? I am not aware of a rule against it, but I just think it would alter performance to such an extent that it's a performance de-enhancing. If you were just doing one thing, spinning, I suppose, but when you add all the other elements like getting off the ground and getting that two feet up in the air to complete those revolutions and skating through.

through what essentially is several minutes of highly, you know, aerobic work, you know, I think that it just wouldn't be efficient. All right. We're going to take a break, and that's about all the time we have. I want to thank Deborah King, Professor in the Department of Exercise and Sports Sciences at Ithaca College in New York. David Wang, Clinical Director of Elite Sports Medicine at Connecticut Children's Medical Center in Farmington, Connecticut. And we have a beautiful visual breakdown of how skating works, Go to our ScienceFriety.com slash skating.

Check it out. ScienceFriety.com slash skating. Beautiful skating visuals from a physics point of view. After the break, we're going to explore the particles in the air we breathe. Pollution in the air. We'll talk about it after the break. Stay with us. This is Science Friday.

I'm Ira Flato. You know that sound, right? The aerosol spray can. If you're around during the 1970s, you remember when consumer aerosol products like hairspray contain chlorofluorocarbons that depleted the ozone layer. And even though these products have not used CFCs since the late 1970s, the connection between a can of hairspray and a warming planet has erroneously stuck around for decades. In fact, aerosols, which is just a fancy word for air particles, do have a role to play in climate

change, but not the one that you might think. Here to tell us more are my guests. Roberti, Assistant Professor of Aerosol Science and Engineering at Washington University in St. Louis. Welcome to Science Friday. Thank you, Ira. Thank you for having me on your show. You're welcome. Vicki Gracian, Professor of Chemistry and Biochemistry at the Scripps Institute of Oceanography at UC San Diego. Welcome back to Science Friday, Dr. Grasseh.

Thank you, Ira. Thank you for having me back. You're well. Dr. ChakraBardi, we get aerosols confused with the stuff that comes out of his spray can, but it's a general term for particles, isn't it? What's the characteristics of an aerosol? So aerosol is essentially, you know, it is made up of two words, which is a saw, which is a phase, which could be a liquid phase or a particular phase, and it is suspended in air. So hence the term we call it aerosol, and it also constitutes both liquid and solid particles, but suspended in air.

There you go. And Dr. Grasin, did aerosols actually cool the atmosphere? So aerosols are some of the more interesting aspects of our Earth's atmosphere. They have the ability to scatter and absorb solar radiation. They have the ability to nucleate clouds. And because of this, they can actually cause cooling of our atmosphere. You've been on the program before, talking about sea spray. I remember it was very interesting. Are these aerosols themselves?

Yes, so sea spray aerosol is one of my favorite aerosol out there in the Earth system. These aerosol particles come from bubble bursting at the ocean surface from wave breaking. So many of us are used to seeing this when we go to the seashore, and these aerosol particles get into the air and they can travel miles and miles away from the source region. And so I'll give you an example of that. There was sea spray aerosols detected in Alabama during a campaign where people were measuring the aerosols in Alabama

and they actually detected some sea spray. How far away from the ocean was that? So it's pretty far from the ocean. Just think about the map of the U.S. where you have Alabama, so you have the Atlantic Ocean, you have the Gulf of Mexico, but inland into Alabama, there was actually sea spray particles. And we know that here in California, where I am in San Diego, we have wave breaking and these aerosol particles get into the air and trained into the air, and then they go eastward.

They can make its way all the way to the middle of the U.S. So somewhere in the Midwest, there might be sea spray aerosol that originated from San Diego a day or two ago. No kidding. That far. I'm not kidding. Oh, yeah. I can tell you many more stories

about how far aerosols go. I'll give you another example. There can be a dust storm in China. So these particles get lofted into the air and then start making its way from desert regions over to more urban areas

like Tokyo and other parts of Asia and then makes its way across the Pacific Ocean and then actually makes its way way to the Western United States. Wow. Dr. Chakrabati, the other thing I know about aerosols is that they're an important part of cloud formation, isn't that right?

Yes. So aerosols, they act as, so the cloud droplets, what you see, you know, the seed which constitute each water droplet is essentially an aerosol. So you need to have these particles to form clouds. And that forms, this whole connection between aerosol and cloud formation is one of the challenging topics of research currently. As we are dealing with more pollution episodes, how does it affect the cloud formation? And, you know, also how does it affect precipitation patterns and drought? And so these are some of these events which we have, which are, you know, different parts.

of the planet are encountering, they have been connected to different pollution events. So specifically, my area of research is carbonaceous aerosols. So these are carbon-containing particles which are emitted from combustion sources, and it could be anthropogenic, which is essentially human-caused,

or it could be natural sources, wildfires and biomass burning. And so these particles, they have their action happening in the visible solar spectrum, meaning they absorb most of the incoming solar radiation or they scatter. So if you think about it, if you think about an existing cloud and surrounded by a bunch of these carbonitious aerosols which are trapping the incoming sunlight, so what is it going to do?

It is going to warm up the vicinity of the cloud which causes the cloud to actually sort of burn away and shrink. So that affects the precipitation pattern. The other thing is if you have a fixed amount of water vapor available and you have a pollution event, so there are more predators, there are more particles which could act as seed. So what would happen is although they would form cloud particles, they would not grow to sizes large enough to precipitate.

So that is sort of hindering the precipitation which would have occurred in a more pristine type of environment. I get it. We had some very intense wildfires out in California just a few months ago. So what happened to the aerosols from all that black smoke? I mean, was there an impact from that? Yes, so I write, it's very interesting. So fire has been st.

studied for thousands of years by humanity. And, you know, if, if, if you, and still it is one of the least understood of natural phenomena. Why? Because first of all, there are different phases of fires. What you're talking about, the black smoke constitute, these are the particles and emissions coming from the flaming or the hot temperature. But what follows the hot temperature phase is what we call it, the smoldering. or this whitish-looking smoke, which, you know. Yeah, when anybody's put out a campfire, you know, we see you leave a little bit of ash

and a lot white smoke comes out. Yes. So these, so both of these types of, so these two different phases, they emit two very different types of carbonaceous aerosols. And what these particles do is the black smoke, of course, it looks black or we call it so it absorbed. most of the incoming visible solar radiation and the white-color smoke, we conventionally think it is going to scatter most of the sunlight because of its white color. But what we are finding

is that these white-colored particles actually have a strong absorption, most of it, near the ultraviolet or near the blue spectrum. So they are not completely white what has been conventionally thought. So now we are ending up in a situation. where not only we have the black soot particles absorbing, but what the other species of particles which we thought to offset this warming effect could be also adding to the heating effect of the atmosphere. Wow.

Yes, because we thought it might be reflecting this stuff. Dr. Grasseen, do we know if these particles from the... let's talk about your sea foam again. Do we know these particles bump into one another or into other particles in the atmosphere? Do you know anything about what happens to them? So these particles, yes, they can bump into one another. They can interact with gases in the atmosphere,

and those gases can actually change the properties of the particle as they react in the atmosphere. These particles come out of the atmosphere through different mechanisms, what's called wet deposition or dry deposition, so a rainfall can cause all the particles to come out of the atmosphere. So, yeah, they do interact with each other, and they also interact with gases out in the atmosphere. But I want to go back to that last point for a moment that was just made.

You asked about the wildfires and whether there was a cause for concern of the aerosols getting out into the air and people breathing these aerosols. So there's definitely a lot of interest in the health effects of aerosols. And you also talked about how these aerosol particles can affect clouds and climate. So it just points to, I mean, these are some of the most interesting aspects of our air, which we don't understand well, because they can affect everything from our lungs and our health to the Earth's climate. And so that's what makes them so fascinating. And the reason why they can do so many different things is that each individual aerosol particle out there is slightly different from one another. Some are very, very small, thousands and thousands and thousands of times smaller than a wind.

of a hair. Some are close to the size of a width of a hair. They have different compositions. They have different shapes. And so for all these reasons, they have very interesting properties, and each one of them can be slightly different than the other one. To the climate models we have now, we're talking about creating global warming or climate change, do they adequately model the cloud formation and the aerosols that are up there? Dr. DeGrasseon? I think that what we just heard a moment ago is that it's very complicated and perhaps the climate models right now are not taking into account everything that they need to take into account.

And so what we just heard was that there's a lot, these are some of the research questions that people are asking, how do describe these in a global climate model? And so the models are becoming more and more sophisticated, but because of the, of these, what I just noted a moment ago, how these aerosols are very different from one another, there's still work that needs to be done to get all that detail into the model the best that they can get it into the model. Let me see if I can go to the phones, get a quick call in here before we go to Rob in in Overland Park, Kansas.

Hi, Rob. Hi, happy day. My question concerns a paper that was put out in the National Academy of Sciences in 2012 regarding urinal peroxide-enhanced nuclear fuel corrosion and seawater from Fukushima, Daichi Power Plant, and how these aerosols can contain radioactive elements that can be carried and deposited inland, and some of these have a very long half-life and are cumulative. All right, let me see. Any reaction from? Yeah.

Yeah, I'd like to take that one. Thank you. So the question really goes to, so what, you know, when we talk about sea spray, we often think about the clean ocean sea water. But now we're talking about some radioactive material getting into the water. Or there's a sewage spill that gets into the ocean. And then can that get into the air through this mechanism of bubble bursting and wave breaking? And the answer is yes, it can get into the air. I don't know, there are not that many reports.

He points to a report in 2012, but we do need to think about that exchange between the ocean and the air through mechanisms like sea spray aerosol, because what is in the water can get into the air. This is Science Friday from PRI Public Radio International, talking about aerosols and sea spray. Dr. Chakrabati, what would you like to know about aerosols that you don't? I'm going to give you my blank check question, which is if you had a blank check, I have it right here in my back pocket. Unfortunately, you're not here to get it. And you could spend as much money as you want on research.

What would you like to know? Where would you spend it? So I would be very, so one of my personal research interest is, you know, and this is what Dr. Vicki Krasian briefly spoke about. what are the health impacts of these aerosols? Specifically, if you look at most of the Asian countries, you have pollution episodes which, you know, people are choking because of these events. So we are still in, you know, scratching the tip of the iceberg when it comes to the health effect side of it.

And I was just, you know, and most of these carbonaceous aerosols, what I just spoke about is organic aerosper. aerosols or aerosols which are emitted from smoldering events. You have people in India and Africa, you have cookstove emissions and they're cooking. So what we have recently discovered, you know, is that most of these emissions, they contain what you call it, polycyclic, aerometric hydrocarbons which are cancer-causing. and most of the compounds which we found are typically, you know, labeled as carcinogenic by the EPA. And this is what people have been exposed to from the health side. And we also have found similar types of evidences from wildfire smoke.

And wildfire, we have to really be ready for the impacts, especially in the coming 20, years or so. It's going to be more frequent and we have to just deal with both the climatic side of things as well as the health side of things. And climate excite, one has to be, one is to take into account the dynamic process involved in how this aerosol changes their properties as well as how our atmosphere, once they're emitted, how is it, what type of feedback it is providing. In the minute I have, I want to ask, people have discussed geoengineering as a possibility of controlling the right balances of aerosols in the atmosphere. Is this a little dangerous? I mean, no.

This is something that I do worry about. And the reason why I worry about it is that we don't understand all the feedbacks. Okay, so people talk about getting a bazooka gun and shooting sulfate aerosols into the atmosphere. and these aerosols will then reflect the light back into space. But what are all the feedbacks? So the sulfate aerosol, when it comes back down to the Earth's surface, is it going to cover it going to get into the oceans, cover the forest? And so I think we need to think really carefully

before doing those kinds of experiments on our Earth system. Good place to end. We're going to take a break and continue our talking about aerosols right after the break. But I want to thank my guests, Rajan Chakabardi, Assistant Professor, of aerosol science and engineering at Washington University in St. Louis, Dr. Vicki Grassian, professor of chemistry and biochemistry at Scripps at UC San Diego. Thank you both for taking time to be with us today. This is Science Friday. I'm Ira Plato. Are you someone who is sensitive to the smell of gasoline? How about nail polish remover? Glue? Well, what you're

really getting a whiff of there is something called a volatile organic compound, or VOC for short, which is just a term for a chemical that easily turns into a vapor or a gas. They also find them in solvents and paints and other home products, and they are a major cause of poor indoor air quality. But now researchers are discovering those compounds are not just confined to the indoors. They're finding their way outside, pumping into other compounds in the air, creating things like ground-level ozone and health hazardous fine particles. And in a study out this week in the journal Science, researchers estimate that in the Los Angeles area,

household products emitting VOCs are contributing as much to outdoor pollution as car and truck emissions. And given the traffic in L.A., that is saying something. Joining me now to talk about this is Brian McDonald, the atmospheric scientist at the University of Colorado Boulder. Dr. McDonald, welcome to Science Friday. Hi, Ira. Thank you for having me here. Oh, you're quite welcome. If these compounds are bad for human health, then why do we have them in so many products?

Well, I mean, first I want to start off with that there's a lot of useful uses of VOCs. For example, generally, I'm guessing people want to smell nice, right? So some VOCs are fragrances that people can smell. They've got other properties like they're used as solvents and they can carry other ingredients. So they've got some societal and economic value to them. Now, the question that this study is trying to look at is we also know that VOCs can potentially contribute to ground-level ozone formation, as well as the formation of fine particles, which was discussed a little bit or discussed a lot in the previous segment. So we know that there's value to certain VOCs, but we also know that they can impact the environment as well. And how are they getting out?

We talked about the indoors. How are they getting outdoors? You know, you say you've discovered they're contributing to outdoor air pollution. How do they get outside? Sure. That's a very good question. So one thing people may not realize is that the building environment is intended to ventilate with the outdoor environment. I mean, we want the air to be fresh in our houses.

And so that exchange happens about once per hour. And so a lot of the VOCs that get. emitted into the building environment, it can stick on walls, it could undergo chemistry, but actually a lot of that can get exchanged with the outdoor environment. Interesting. Okay, so they get outside, and what type of air pollution do they cause? Sure. So the two that the study really focuses on is the formation of ground-level ozone. So when people think of smog, they probably think of the two main building blocks, which are ground-level ozone. And then the second dimension, which is particularly new in this study, is that the vapors that come off from these everyday use of chemical products can also form fine particles in the atmosphere.

So the particles bump into other things? Yeah, like the previous segment, they can bump onto other particles that are existing, or they could form new particles. Well, you mentioned in your study that these products are contributing. And I thought this was amazing. Maybe you found it amazing also as much to air pollution as VOCs from car emissions. Yeah. So that was a very surprising dimension of this study. I mean, every day I'm waking up in the morning.

I'm going to my bathroom, and there's a variety of products that I use. So personal care products in Los Angeles ended up being one of the larger sources of VOCs that people are using within households. So these are things like shampoo, hairspray, deodorants, creams, lotions. And it was very surprising to us, not just myself, but this was a large team of scientists that were on this paper, that these emissions were as large as what's coming out of the transportation sector. But I think there needs to be some context to this story. I mean, part of this is a good news story in the sense that in the past we knew that transportation

was a really important source of emissions in VOCs, which contributed to those iconic pictures of smog in Los Angeles. And as a result of that, efforts under the Clean Air Act and by the California Air Resources Board, U.S. EPA, have really been successful at controlling those emissions. So now that we start seeing other sources of air pollution becoming relatively more important. You know, I was reading that 40% of the chemicals added to consumer products

wind up in the air. Yeah, so we looked into the literature of researchers who have studied the indoor environment because one of the challenges with estimating emissions from these products is how they're used. So, for example, if you put paint on a wall, a lot of that will get into the air and then ventilate outdoors, or if it's on an outdoor wall, it'll just emit into the outdoor environment directly. But if you're using something like a hand soap, a lot of that will end up going down the drain. And so we looked at the research that was in the scientific literature and estimated what fraction goes up into the air versus goes down the drain or into landfills.

And it was a surprising amount to us of how much can actually get into the air. You know, we put reactors on cars for the exhaust to keep out some of these, you know, harmful things that might be coming out of the tailpipe. I'm just thinking out loud here, can you put something on, you know, the stuff in the house to trap the extra stuff from getting out somehow? Have you thought about that? Yeah, so I think what this study really tries to do is point out that these emissions are potentially significant.

I think there's a lot of questions about, well, what are some possible solutions? And I think that there's a lot of possibilities to explore. One is a lot of research in the indoor air quality community does look at things like filtration. So what could you do in the indoor environment to improve the exposure to some of these chemicals, as well as prevent them from getting outside.

But there's a lot of different avenues that one could foresee, right? And, of course, there are products that don't contain VOCs in there. I know there's a California Air Resource Board has a website, right? And there's an environmental working group that has a website, so people can find some of these things that won't get outside or stay inside. Yeah, so I encourage people if they have questions about this, that the California Air Resources Board and U.S. Environmental Protection Agency have some really nice resources on the VOCs that are in these products.

And if you have questions about how they affect air pollution, they're really good. All right. Thank you for your research for coming on Science Friday. Thank you very much. Brian McDonald, atmospheric scientist at the University of Colorado in Boulder. I don't need to tell you that the flu season has been vicious this year. Some of you might be on your second round battling the infection. This thing comes and you think you're feeling better and it hit you a second time.

And you've heard of all the precautions to avoid the flu. Wash your hands. Get a flu shot. Make sure you're sleeping well. But what if there is a way to kill the flu, before it ever reached your nose, killing the virus floating in the air. Researchers have been working to create a type of lamp that would zap it, kind of like a flu bug zapper.

And they have succeeded using a narrow band of ultraviolet light, safe ultraviolet light. The reports, the results were published in the journal Scientific Reports. David Brenner is an author on that study. He is also director of the Center of Radiological Research at Columbia University in New York. and he joins us here in our CUNY Studios. Welcome to Science Friday. Good to be here. So there is a specific part of the UV spectrum.

Tell us about that. Yeah, that's right. So I think most people know the UV spectrum divides up into UVA and UVB, UVC. And the difference between those is just the different wavelengths. So far UVC, which is where we're working, is at the far end in terms of wavelengths of the UVC spectrum. Now we know that when we put on sunblockers, we're. You know that the UVA and the UVB is dangerous, that's why we're putting on the sunblocker, but the UVC is not? Well, UVC in general doesn't reach us because it gets absorbed in the upper atmosphere before it reaches us.

But UVC in general is a really, really good killer of microbes, bacteria and viruses. And that's been known for probably 100 years. So it certainly is a good technique for killing influenza virus. But there is a problem there, and the problem is that UV light in general is a health hazard. It causes skin cancer, causes cataracts in our eyes. So you can use it in places where there are not people in empty rooms, but what we wanted to do was to use ultraviolet light in a setting where there are people around. And you found that the UVC is not dangerous for people, like the UVA and the UVB is?

Yeah, that's right. And there's a good physics reason for that. Far UVC is actually really, really strongly absorbed by all biological materials. So in biological materials, it simply doesn't go very far. So, for example, if it impinges on our skin, it can't penetrate through the dead cell layer right at the surface of our skin. And it can't penetrate through the tear layer on the surface of our eyes. So from our perspective, it's safe simply because we're protected from it. The difference with bacterian viruses is that they are really, really small. So they're far smaller than the outer layer of our skin or eyes.

So the far UVC light can penetrate them and get to their DNA and kill them. So it can kill bacteria and viruses, but it can't damage us. That at least is the principle. I mean, it sounds so obvious. Why hasn't anybody thought of this before? Not to denigrate what you're talking about. Yeah, it was a little bit of a light bulb going off when we first thought of this, a UV light bulb. Yeah.

And, well, what about plants? You know, if I'm picturing that. What you want to do is make a lamp out of UVC, and then you can hang it in a doctor's office or something, maybe in your own home, and just kill the viruses that may be hanging out. Would that be what the idea is? That's the idea, yeah. And what if I had plants there? would it kill my plants? Well, again, plants also have a surface layer of cells which would protect

them. So it's what's very specific about bacteria and viruses is that they're really, really, really small, smaller than plant cells, smaller than human cells. Now, let me, I'm glad you brought that up because on our skins, we have a microbiome of bacteria there, you know. Yes, we do. And they're beneficial, are they not? Yeah, there are certainly good bacteria and bad bacteria. in this world and indeed. So, I mean, there is a whole microbiome not only in the skin but throughout our bodies. Now, the

microbiome inside our bodies is going to be protected from this far UVC light simply won't reach that. But you're right, there is a microbiome on the surface of our skin. But actually life on the surface of

anything on the surface of our skin for a bacterium, for a virus, is actually pretty tough. So a bacteria sitting on the surface of our skin. Well, for example, you wash with antibacterials. You take showers, you go out in sunlight. So all sorts of tough things can happen on the surface of the skin. So what the bacteria do to protect themselves when they're there

is that they cluster into very, very large groups of bacteria. They don't sit a single bacteria on the surface of us. skin. They're in groups of thousands and kind of held together with sticky protein-like stuff. So the outside of that big cluster would be potentially amenable to far UVC light. But inside, most of the bacteria are going to be protected. I gotcha. So basically, I think the far UVC is going to do far less damage to the skin microbiome than simply the things we do normally, washing and going out in sunlight.

This is Science Friday from PRI Public Radio International. Talking with David Brenner, Director for Radiological Research at Columbia about this UVC lamp. And of course, you just put a shirt on. You don't have to worry about it hitting your skin. So how close are we to going to Home Depot and getting a lamp? Not so far. Really, three things have to happen for it to be really, really ready. First of all, we have to definitely demonstrate that it's effective, that it kills.

viruses, influenza virus efficiently. And that's what the paper that we published just a week or so ago was about. And the answer is it kills viruses with about the same efficiency as conventional ultraviolet light. And that's very efficient indeed. And one of the big pluses is that it's going to kill all influenza strains essentially equally well. So we don't have to have a lamp each year. So we need to show that it's very good at killing. We need to show that it's safe. And so we started off by saying, well, the physics says in principle it's safe, but that's obviously not good enough. So the last four or five years, we've been working pretty intensively on safety studies, both in human skin and mouse skin and also in eyes.

And the conclusion to date, at least, is we have never seen any body. biological effects, any biological damage from this far UVC light. We always do the studies in parallel with a conventional germicidal lamp. And there we always see biological damage. One question, a tweet came in from Alex. Flu is viruses spread primarily by aerosol. Wouldn't this UV light have trouble penetrating the droplets? Well, actually, that's what the study that we that we published last week was. So we actually attached the influenza virus to realistic aerosols and then floated those in front of the UV lamp.

And that's where the results were that we were able to kill the viruses very efficiently. Is this patentable or because it's UVC anybody can? Well, Columbia has certainly got all sorts of patents in, believe me. And, you know, it was like almost a dumb moment, I would imagine. Why haven't we thought of this before? Yeah, it was a little bit of that, but I guess we had to put together a few different things in our minds to really come up with this. Yeah, all right. Well, good luck. We're waiting for this, okay? We're waiting for it, too.

In fact, David Brenner, Director of Center for Radiological Research at Columbia University. One last thing before we go to an aspiring radio rookies out there. Hey, you're an aspiring radio rookie. We're on the hunt for summer interns. You're going to learn how to put together radio segments like the ones you hear each week on the show. And you work with our talented team of science geeks. And if you want to be an intern, I can promise you, you will not be asked to go for coffee. So check out the details at ScienceFriiday.com slash internship.

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