The Rise of Radioactivity

This period of coronavirus lockdown is dramatically changing our outside environment - closed shops, quieter roads, emptier parks. One town in Wales has even been invaded by goats lured in from the surrounding hills by the absence of people! And with fewer cars and buses on the road, and fewer planes overhead, what impact is lockdown having on our air quality? Katie Haylor spoke to BBC science correspondent Victoria Gill, who explained that pollution levels in the UK have dropped sharply, particularly noticeably in cities...

Victoria - We've actually very recently had a measure from some ground based measurements showing reductions in some pollutants that we know are bad for our health, and we know are associated with the kinds of activities that have dropped so sharply since we all were sort of plunged into this coronavirus induced lockdown. So things like transport and industry, so nitrogen dioxide and particulate matter. So that's small particles, and we know that they can do some damage in our lungs. Particularly particles under a certain size can sort of get right down into our lungs. Scientists and public health specialists are really interested to see what will happen as this lockdown continues, because there's not much good news coming out of the coronavirus crisis, but it does seem to be inadvertently improving our air quality.

Katie - How are scientists actually measuring this drop?

Victoria - We've seen a number of different measurements actually, and this is an international effect. We've had some measurements that have come from China and from India. We're also, I should say, seeing a drop off in carbon dioxide, some of those greenhouse gases as well. In Europe we saw a really interesting measurement come from some satellite based spectrometry, measuring the colours that are being reflected from the sunlight that's hitting the Earth, and those different colours represent the reflections from different types of gas. You can see different types of pollutants and take that colour intensity as a measure of the amounts of those gases. We then saw from the National Centre for Atmospheric Science, these city-based ground measurements that really give us a measurement of the air that we're breathing, and we're seeing the same thing across the UK.

Katie - Is it possible to determine what impact this could have?

Victoria - A lot of what will happen in the longer term will depend on how quickly some of those pollution driving sectors bounce back. So for one thing, we've heard from the UK government that they're going to be phasing out the sale of vehicles that have internal combustion engines, and moving to electric vehicles. What we can maybe see over the next however many weeks and months that we are kind of stuck in this lockdown, is a realistic measure of the kind of target that we'd be looking for when we take a lot of those diesel vehicles off the road and replace them with electric vehicles. So there could be some longterm better, more informed targets for air pollution. The worry is that once this immediate crisis is over, there'll be a drive to just restart the economy without any of that in mind. So I think public health specialists and atmospheric chemists will be trying to kind of, build in some good practical advice into how we may be keeping some of these benefits to the air that we're breathing.

Katie - Do you think there are any lessons we can learn in terms of pollution, if we look, you know, to people who are a bit ahead of us?

Victoria - There's something positive that we can take from this unintended consequence of what's happening in so many places. You know, we've seen a quarter of the world under lockdown, and lockdown means less transport, less industry. It means less pollution. Now, if we can monitor the effect that that is having on people's cardiovascular health, on people's ability to kind of, breathe clean air, but also take some lessons from it in terms of what our streets and urban centres could look like, if we can limit that pollution and limit that transport. I think we're all learning lessons about how the world could change. You know, there's been a huge amount of frustration, especially from kind of, the younger generations and activists in the environmental movement, about how slow we've been to respond to the emergency that is climate change. And what this does show us, is that when there's an emergency that is immediate to our public health, we can act and we can put in some really severe measures. And I'm not suggesting that governments are going to do anything along this scale to tackle climate change, but it shows what's possible. Maybe we can take some lessons from this in order to apply it to that bigger global emergency that is, you know, the state of our planet and our warming world.

In recent weeks we’ve all become home remote workers. And that means we’re relying on video conferencing software like Skype and Zoom. And this has led to concerns about the security of the information being exchanged. Adam Murphy was joined by tech commentator and angel investor Peter Cowley…

Peter - Zoom is one of these many platforms for video conferencing. So as consumers we tend to use FaceTime or Skype or WhatsApp or House Party, the new one that people are talking about. And for businesses tend to use Microsoft Teams and Go To Meetings and and Cisco WebEx. But it also Zoom. Zoom we also use actually privately, I'm going on to a drinks party after this on Zoom with people in various places around Europe. So basically it's people getting together in a single place using audio and video.

Adam - And with all these people together in one place, is it secure?

Peter - As has been reported in the press quite a bit recently, Zoom, which has grown quite rapidly and become very much the dominant player in recent years, is not concentrated quite as much perhaps on privacy as they should. And this is what they've self-declared, it isn't something that I've made up. There's been things like, something called Zoom bombing, which is where somebody suddenly appears on it and says something rude or derogatory or has an image there which they definitely shouldn't be showing. Information has been passed to Facebook. People can join a meeting just knowing the ID and famously the cabinet's Zoom meeting was published on Twitter with the ID on it as well, so that effectively if somebody typed that in, they could have possibly joined that. Email addresses have been lost, etc. The big issue with Zoom is it's what's in the industry is called a very large attack surface. There are probably at any one time, hundreds of thousands of millions of Zoom calls going on. So that means it's quite easy for people to get in. I mean people who are doing naughty things, not you or I of course, get into some of these calls.

Adam - And you mentioned it was passing data to Facebook. What kind of data is passing on?

Peter - I don't know and they seem to have cleared that. So there are a number of things have happened. They've now stopped any new features. I've actually got a Zoom Pro account myself and the number of features there, the settings is phenomenal. So there's more features than probably any of us will use. So what they're doing is basically closing these loopholes, or closing the loopholes that have been found so far. Like any internet giant or any software, really the things that could be leaked are data, of course, I couldn't tell you what Zoom has leaked, if anything has leaked. And also selling, I mean we've been through this before with Cambridge Analytica, haven't we? Here in Cambridge a couple of years ago.

Adam - With all this happening, what can people do to keep themselves safe on Zoom?

Peter - Two or three things which are being introduced and I see that even on this meeting, it's coming up in about an hour's time, passwords. So having a password there. Most meetings you get in, you get a link. If that link leaks, anybody can get into it. But if you've got a lot of participants, and I was on recently one with a hundred, there's no way you can see everybody. Something called waiting rooms or lobbies? So you can't get on immediately. You've got to get into this waiting room and then you're let in by the host. Again, this means they can't come in, they can't Zoom bomb. You should mute your own video and your audio of course where you're not needed. If you're the host, you mustn't allow guest screen-sharing, that way the Zoom bombing can't occur. So there's quite a lot of just good practice that people haven't been doing.

Adam - And then what about our mobile networks and our smart phones and all this? How secure are they in the current situation?

Peter - Well a couple of things there. One is that some countries are actually using the mobile phone networks to do couple of things. One is to contact trace so they can see if somebody's had COVID, who they've been near. And secondly social distancing, because the data is accurate enough they can actually see. So this is very Big Brother-ish and I hope it doesn't get to many other countries like the UK. The other thing you might've seen is that people are somehow blaming 5G for COVID transmission and they've been setting fire to 5G mobile masTs and there's been seven or eight of them here in the UK being set fire too. I really can't see the connection there between how a 5G signal, which is yet another mobile signal, but no different really from the ones we've have been used to for the last 20 or 30 years, and COVID. But they seem to think they are.

Adam - And so you won't be stopping using 5G?

Peter - I certainly won't be stopping using 5G and I won't be stopping using Zoom, but I am very pleased to see that these other facilities like the passwords and the lobbies, things I didn't know about a week ago, which I do now.

In our mailbox this week, Chris Smith answers the question of whether you can get coronavirus by inhaling vape clouds...

Chris - This is something I’ve wondered myself, actually. In fact, I followed a car along a road in the past, and been able to smell what the person in the car in front of me was vaping. And this got me wondering, well, if I can smell that, that’s presumably air that was previously in the lungs of the occupant of that car. And, if I can smell the vape molecules, could there also be infectious particles of virus, for instance, their rhinoviruses or adenoviruses, or in the current situation, their coronaviruses, which are making their way into my car too.

Well, I think the likelihood of that happening is extremely remote, because the amount of dilution of the air between them and you is going to be extremely considerable. But, the fact that you can smell the vape, shows you that molecules, that have that smell, were in that person, and they are telling you where the air from that person has gone.

Now that means, in theory, if there were some virus particles amongst those vape molecules, they could be following the same path, and they could also, therefore, end up in your face. There are some considerations though, which make this extremely unlikely as a route of transmission.

The main one to consider is that the vape molecules, that give it the smell, are really tiny, but the particles of virus are considerably bigger, and they’re also in droplets of water, largely, from the person’s respiratory tract. So although they’ll move a considerable distance, and they’ll bob around in the air, they won’t travel as far, and they won’t travel as fast as the smoke, or vape, from someone vaping.

So what you can regard this as is almost as a proxy for where the air from another person is going, and it should serve as a warning for how fast air can move smells and smokes, and possibly viruses around. But also take comfort from the fact that, probably the amount of virus, by the time it’s gone from that car, out of the window, and through the air conditioning unit of your car, and into your face is going to be, really, very tiny. And almost certainly lower than an infectious dose.

But if you were sharing a room with that person, or even their car, you’d be at a much greater risk, because the close proximity to them means that the virus particles would be in higher concentration, and you’re more likely to inhale what we would call an infectious dose, which in the case of this virus is probably around 20 virus particles.

A lifetime of exposure to high levels of radioactivity eventually killed Marie Curie. Her notebooks are still too radioactive to handle safely. But radioactivity is used routinely and very effectively in medicine to cure disease. So how does that work? Chris Smith was joined by cancer specialist Tom Roques, from the Norfolk and Norwich University Hospital...

Tom - So I guess you could think of radioactivity as lots of tiny bullets of energy which can go through the body's tissues. And they can damage the DNA, the life code inside cells. If they damage them a lot, that cell can die, and we use that in medicine with radiotherapy. But if the damage is more minor then you can get mutations in the DNA and those mutations over time can add up and cause cancer.

Chris - And are any particular parts of the body vulnerable? Or is there any part of the body susceptible to this happening?

Tom - So the parts of the body that are more susceptible to damage from radiation are the parts where the cells are growing quickly. So again, with the radiotherapy that we use, the tissues that tend to have more side effects from radiation are things like your mouth and your gut, where the cells are growing and dividing all the time; rather than parts like your brain, which tend to be fairly stable.

Chris - And so it's the fact that cells which are dividing are susceptible to being damaged by the radiation: that's why you can actually turn this around and say, rather than worrying about it causing cancer, if someone's already got cancer, you can use the vulnerability of fast growing cells to hit them with a dose of radiation and kill them?

Tom - We use the fact that cancer cells tend to be growing more quickly than normal cells. So in normal cells, the DNA is packaged away very safely and tightly inside the nucleus of the cell, so it can't be hit by these bullets of energy that the radiotherapy gives. Whereas cancer cells, their DNA is outside being divided and grown, and that makes them more sensitive to the radiation.

Chris - When you use radiation therapeutically in this way, what sort of radioactivity do you use? What's the source?

Tom - So I guess that's the other difference between now and the radiation that the Curies were using. They were using naturally occurring radiation, which you can't turn on and off. Now in hospitals we use a machine called a linear accelerator, which is about two million pounds worth of high-technology kit with a generator of particles that hits a tungsten target, and its that that produces the energy of radiotherapy; but you can turn it on and off. So when the machine is off, it's perfectly safe to go into the room, and when it's on, only the person in the line of the beam is actually affected by the radiation.

Chris - So you zap a person's cancer, if you know where it is, with a dose of radiotherapy to destroy the cells, hopefully. But why doesn't that radiation then damage more healthy tissue and cause the person to have more new cancers?

Tom - So it does damage that healthy tissue, but to a lesser extent. And over the years, doctors have learned ways of minimising the damage to the normal parts of the body, while maximising the damage to the cancer. So for example, most of the time when we're trying to cure cancer, we give radiotherapy in lots of little repeated doses over a number of weeks, with the hope that the normal cells are better at repairing damage to their DNA and so can recover overnight, if you like, whereas the cancer cells tend to die more easily.

Chris - Is the same true therefore when we use a degree of radiation exposure to do imaging? I'm thinking things like X-rays and CT scans, we're using a dose that's useful to us in terms of imaging the person but not sufficiently large that we're going to cause a big increase in risk of them actually getting a cancer.

Tom - Yeah, so the energy that we use for imaging is much less than for radiotherapy because you're not trying to kill any of the cells or to damage them at all. So the energies that we use are much less, but every dose of radiation we gave - whether that's an X-ray or a CT scan - does give some radiation, which in theory could cause damage at a very low level in cells. So doctors always try to minimise the dose of radiation that we need and not put people through scans that they don't need.

Chris - And how else can we actually use radiation in order to image? Because obviously people will be familiar with things like a chest X-ray, or going in a CT scanner, the thing that looks a bit like a doughnut; but what other measures and mechanisms have doctors like you got at your disposal?

Tom - So I guess the most exciting change in the last 10 years or so has been things like PET scans. So a CT scan will give you a 3D picture of the inside of your body in different shades of grey, but it doesn't tell you what the tissues inside the body are doing. We use the fat that cells that are growing and dividing need sugars like glucose in order to grow, and if you give someone some glucose and make it radioactive, you can detect where that glucose is going, and show up in different colours where areas of cancer are. So that enables us to find cancer where we couldn't otherwise see it.

Our issues with radioactivity though are obviously not behind us. A major headache today is how to handle and safely store nuclear waste. Here in the UK, we’ve got 650,000 cubic metres of the stuff - enough to fill Wembley Stadium - and it’ll be radioactive and dangerous for 100,000 years. Claire Corkhill is at the University of Sheffield where she works on ways to store this stuff safely, and she joined Chris Smith and Adam Murphy...

Claire - It starts with the nuclear fuel from a nuclear reactor, which is uranium; and much like the bombs that we just heard about, the atoms inside it split to create energy. They release that in the form of heat, which we then use to boil water, which gives us electricity. But in a nuclear reactor we have some way of controlling the splitting, so we've got some brakes where we can slow it down and control it so it doesn't end up like a bomb; but that material, when it's been finished with in the reactor, we recycle it. So it contains a lot of uranium and plutonium which we can then turn into new fuel. And the byproducts of the recycling are nuclear waste. These byproducts are smaller atoms, so as the uranium atom for example splits, it makes smaller atoms which are also highly radioactive, we call these fission products. They end up being mixed with a type of glass which is not too dissimilar from the Pyrex that you have, Pyrex dishes that you have in your kitchen. And we turn this waste into a very durable glass. Everything else that's leftover from that recycling process is usually encapsulated inside a cement material. And then there are a whole range of other materials that we don't yet class as a waste, but they might be a waste in the future; for example, the plutonium that we've been recycling, we don't actually have a plan to turn that into new fuel yet.

Chris - So what do we do with all this stuff? We end up with these barrels of what looks like glass or concrete; that sounds fine. What do we do, just bury them?

Claire - Well, they're currently packaged in specially-engineered containers and stored in over 20 different secure nuclear sites around the country, and most of it is at Sellafield in Cumbria. And these stores are designed to withstand extreme weather and earthquakes. But the problem that we have is that the waste is so radioactive, we can't actually go anywhere near it. If you were to touch the outside of one of the glass waste containers, the radiation dose that you'd receive is 200,000 times more than a fatal dose of radiation. So whilst it's okay to store the waste securely for the time being, it's clear that we need a more permanent solution that requires less security. So remember, these wastes will be radioactive for over a hundred thousand years and they'll be highly radioactive for several thousands of years, so we can't just leave them in their warehouses and hope that future civilizations will know what to do with them.

Chris - Now will they remain intact though? Because the key question... today it looks like glass, but with that much radioactivity spitting out that much energy, will it remain like that and in a stable form for the next a hundred thousand years, if we store it ideally, or is there a danger it might not?

Claire - That's a really good question, and that's really what we've been doing a lot of work on at the University of Sheffield. These nuclear waste materials will change over the hundred thousand years that they'll be radioactive. And there are some different ways that this might occur. One would be corrosion, so the natural corrosion of the materials once they're buried deep under the ground, which is their final disposal route; if they slowly corrode in groundwater they may release their radioactivity. But the other issue is, as you rightly noted, that the radioactivity inside the waste might actually cause the waste itself to break down. And you can think of this as a highly energetic particle, a bit like was described before with breaking DNA; instead of breaking DNA we're actually breaking the intrinsic chemical bonds inside our nuclear waste material, and this will essentially cause the waste to disintegrate. And this is something that we have to understand.

Chris - So what you're saying is, if we've got say something that looks like glass, because it's spitting out all these energetic particles of radiation all the time, it's slowly going to shatter the glass. It's almost like shaking the glass very, very hard for hundreds of thousands of years; it's eventually going to fall to pieces and it will no longer be any good at retaining and constraining the radioactive products inside.

Claire - Essentially yes. I mean, glass is a very good material because it has a very flexible structure, and if you break one bond it's not going to affect the material. If you were to use something that was a bit more of a crystalline structure, this might cause you a problem. But actually what we're doing is trying to look at designing new types of wasteful materials that are based on natural uranium-containing minerals that we know are millions of years old. And while their chemical bonds have been broken by radioactivity, they haven't disintegrated and they haven't released their radioactive elements. And so these are the kinds of materials that we're now trying to develop for nuclear waste.

Chris - And are these... effectively mineral cages, that you're talking about making, are they any good? What studies have we done to say that if we bake this kind of cake and we put these materials into this molecular architecture, that it will actually perform better than what we can do with our present generation of things like glass and cement and so on.

Claire - So one really good example is a mineral called zirconalite. And these are some of the oldest minerals known on earth - there are some that are slightly older - but they contain uranium. And we know that they contain uranium because they today contain lead, which is the stable isotope that uranium decays to at the end of its decay chain. Which means that over the millions and millions of years that these minerals have existed on the earth's surface, they've managed to contain their radioactivity safely. They've gone amorphous, which means their crystal structure has broken, but they're still intact. And what's more, we know that despite the fact they've been on the surface for such a long time and there's been lots of weathering and lots of geological events, that they haven't changed and they haven't been weathered, and as I said they still contain their uranium. So we base our design on minerals likes zirconalite. And so one of the pieces of research we're doing at the moment is looking at how to dispose of the huge stockpile of plutonium that we have in the UK. And actually is zirconalite is the ideal mineral material that we can develop to immobilise plutonium safely so that it doesn't get into the wrong hands in the future.

Adam - How do we design something in the future so that this stuff stays where it is, and isn't archeologist bait, and they suddenly dig up a radioactive cube of glass?

Claire - At the present time we are thinking that we will not mark when nuclear waste is kept. It's going to be buried deep below the ground and nobody will know it's there. The worry about putting a marker on the surface is that it will automatically draw, humans particularly because we're very inquisitive, to that site to find out what's going on. And the example that I like to use is of the hieroglyphs on the pyramids, which clearly said, in a language that nobody understood at the time, don't enter or you will be cursed. But the archaeologists of the time were fascinated and thought, "well we must go inside and see what's in there." And so sometimes leaving a marker may give you the result that you didn't want, and people might then use that as a reason to go down and start looking for the waste. So the plan at the moment is to not mark the waste and hope that people forget about it; and that if in the future they decide to dig there, they have the technology to dig that deep - so we're talking between 500 metres and a kilometre below the ground - and if they have that technology, then they will also have some technology to be able to detect the radiation and know that they shouldn't go there.