Green Food

We're chewing over the topic of food footprints: How green is your lunchbox? What's the environmental impact of your weekly food shop?
11 February 2014
Presented by Chris M. Smith, Ginny Smith


 This image shows a display of healthy foods on a table. Foods include beans, grains, cauliflour, cantelope, pasta, bread, orange, turkey, salmon, carrots, turnips, zucchini, snowpeas, string beans, radishes, asparagus, summer squash, lean beef,...


We're chewing over the topic of food footprints: How green is your lunchbox? What's the environmental impact of your weekly food shop? Plus, in the news, the prosthetic hand that has allowed an amputee to feel for the first time, a new fatal strain of flu has been identified in a patient in China and Gaia's goal is to create the most accurate map yet of the Milky Way.

In this episode

Artist's impression of the Milky Way: the stars are collapsed into a flat disc

01:21 - Mapping the milky way

This week the Gaia telescope, a 1 billion pixel camera was tested 1.5 million km from Earth and it works!

Mapping the milky way

Chris -   First this week, the Gaia space mission which was launched on the 19th of December is now orbiting around a virtual point in space Artistwhich is called L2.  It's about 1.5 million km from Earth.  Gaia's goal is to create the most accurate map yet of the Milky Way.  This week, its 1 billion pixel camera was tested successfully which is presumably a very big relief for Cambridge professor Gerry Gilmore who's leading the project.  Hello, Gerry.

Gerry -   Hi, Chris.  Good to see you again.

Chris -   Are you a relieved man?

Gerry -   Doubly actually.  I was at the launch and one felt really quite relaxed after it was over, seeing Gaia flying off so successfully.

Chris -   How much money was invested in that?

Gerry -   The lifetime cost of the project is getting on for a billion Euros, 600 or 700 million pounds.  

Chris -   Or a third of an LHC to put it another way, I suppose.  

Gerry -   Well, it's the people's lives that is their real cost.  There's hundreds of really smart engineers that have devoted decades to this so that's the bit you can't get back.  

Chris -   The announcement this week that the camera works, so when you put one of these things into space, how do they power them up?  Do they do it system by system to do a series of checks to make sure that everything works sequentially then?  

Gerry -   Yes.  The whole turn on process is still underway, but you turn on the really smart brains of the system which themselves then turn on other bits of the system and so on.  There are some bits like the atomic clocks that take weeks to settle down, so they're turned on early and they're still settling down.  So, Gaia won't actually be in full science operation for another three or four months yet.  But as the systems are turned on and tested, we  then know whether they're working or not.  The really critical systems which is the computing, the brain, the clocks, and the camera and telescopes, they're all working fine.  That's a really magnificent tribute to the people who built it and a spectacular relief for those in it.  

Chris -   How do you know that the camera is working correctly because all you get back is what it tells you it's seeing?  

Gerry -   So essentially, all Gaia is is two telescopes feeding a very, very large camera.  These things are billion pixels, biggest camera ever put into space.  It's about a metre long.  Compared to the one in your phone, which is about the size of your little finger nail, this thing is the size of your tabletop.  What it's going to do is essentially feed down a high definition movie for the next 5 or 6 years.  And so, the first frame of that movie is down and it looks good.  So, by comparing it with previous studies of the same cluster which by pure coincidence happen to be a study I did using the newly repaired Hubble Space telescope in the late 1990s.  So, it's pure chance that that happens to be the same cluster.  But by comparing it with those Hubble measures, we know how sensitive the camera is, we know how accurately the things in focus.  So, we know how clean the optics are and all the news is good.  I mean, there are few technical things that will come out in the next week or two, but fundamentally we know the mission is going to work.  It's terrific!  

Chris -   Congratulations!  Have there been any problems or has it all been a bed of roses so far?  

Gerry -   No, there's always a few problems.  Everybody knows the famous spectacular Hubble problem and Gaia's predecessor actually went in the wrong orbit.  The rocket didn't fire because some twit left a bit of cloth in it.  But Gaia has nothing like that.  there's a few little technical issues that we'll be able to work through.  But fundamentally, it's looking good.  

Chris -   How long before the data begins to land on your desk here in Cambridge so that you can begin to see these amazing maps in extraordinary detail, emerging of our galaxy?  

Gerry -   Well, we're processing the test data right now.  That's where that image came from.  So, we know what's going on.  We're contributing to the team that's actually testing out the hardware and checking that everything is working, and putting the telescope in focus.  That's actually a non-trivial thing to do.  It'll take another month yet before it's perfectly in focus.  But then the real science data will start coming in in April.  So then we'll do the science verification.  So, that's the real hard - how good is the science going to be.  So, we know that technically, the thing is looking promising.  About April, we'll come back and we'll show you the first science results and then we'll expect to be in full routine, doing nothing but exciting science from May onwards to another five or six years.  

Chris -   You must come back and tell us how you're getting on. Gerry thank you very much and congratulations. Great to have you on the programme. Gerry Gilmore from Cambridge University's Cavendish laboratory.

A soldier in the U.S. Army plays fooz-ball with two prosthetic limbs.

05:25 - A world's first feeling prosthetic arm

The first prosthetic hand has been developed that allows its user to actually feel what they are touching, in real time.

A world's first feeling prosthetic arm

The first prosthetic hand has been developed that allows its user to actually feel what they are touching, in real time. Dennis Sorensen from Denmark became the first amputee to use this new prosthetic hand, Prosthetic Limbsand experience a restored sense of touch.

Artificial hands that can open and close have been around for a while, but because there is no feedback, users have to be very careful not to accidentally crush the object they are holding. Now Stanisa Raspopovic and his team at EPFL (Switzerland) and SSSA (Italy) have developed technology to allow a user to detect the shape and texture of an object, as well as how hard they are gripping it.

They do this by detecting electrical changes generated as the tension in artificial tendons on the hand changes. A computer algorithm converts these into pulses that can be sent along nerve cells. Electrodes were implanted into Dennis' arm to receive the signals and send them onwards to the brain. Although the scientists were worried the nerves in Dennis' stump would no longer be sensitive, having not been used in over 9 years, the system worked well. He was also able to control the movement of the prosthetic hand by contracting different muscles remaining in his stump.

Dennis was blindfolded, and wearing headphones so he couldn't use his other senses, and was asked to do various tasks with the prosthesis. He was able to learn, over the course of a week, to apply different amounts of pressure with the fingers, to grasp and manipulate different kinds of objects, and to detect the properties of objects.

The hand is still a way away from commercial use, and after a week of trials, Dennis is back to using a standard prosthetic. The electronics need to be miniaturised to make the hand portable, and the sensory technology will be fine-tuned.

Intravenous Drip

08:16 - Medically Induced Comas

This week doctors are trying to bring Formula One Racing Star Michael Schumacher out of a medically induced coma.

Medically Induced Comas

This week doctors are trying to bring Formula One racing star Michael Schumacher Intravenous Dripout of a coma which was medically induced following a skiing accident.

To find out more about why medically induced comas are thought to help people with brain injuries Here's your Quickfire Science with Kate Lamble and Hannah Critchlow...

- A coma is a state of unconsciousness when a person is unresponsive and cannot be woken.

- Comas can be caused by a drug overdose, head injury or purposefully induced by doctors to aid in recovery from trauma 

- After an injury, brain tissue swells, which can restrict the flow of blood through the brain, worsening the damage.

- Inducing a coma reduces the amount of energy that the brain requires, and so protects the areas at risk of low oxygen from hypoxia.

- Brain swelling is also tackled by cooling, which reduces the brain's requirement for oxygen

- Alternatively patients can undergo an operation to remove a section of bone from the skull; this allows the brain to swell without compressing and potentially damaging other areas.

- Patient responsiveness in comas can vary - in very deep comas - such as those that are medically induced - a patient may be unresponsive to pain. But less-sedated patients may be able to hear conversation.

- Unlike in the movies, waking up from a coma is usually agradual process. In medically induced comas, cooling is reduced by about 0.25C every hour, to avoid the brain swelling.

- When the patient is able to make a conscious response to instructions, they are no longer classed as being in a coma.

- However, any damage to the brain sustained through a traumatic brain injury is often not apparent until the patient has woken from the coma

- Schumacher's family will have to wait until the anaesthetic stops being administered to see what the long term impact of his head injury will be.


10:29 - Feeling powerless makes for a heavy load

People who feel powerless perceive the world of weight very differently...

Feeling powerless makes for a heavy load

Chris -   People who feel powerless perceive the world of weight very differently. That's according to a new study out this week in the DepressionJournal of Psychology. Eun Hee Lee is a researcher at Cambridge University, she is the lead author welcome to the programme. So you found that people who feel powerless actually find things that are a demand on them physically more challenging?

Eun Hee -   Yes, so I did work on social power and how that influences our perceptions of physical properties like weight perception, how they feel the weight of objects. I asked people to lift those boxes as you can see.

Chris -   So, I've got a nice big box here, just a cardboard box.

Eun Hee -   Yeah, just cardboard boxes and all of them looking exactly the same, but I would load them with a different number of books to have different weight and I asked them to lift all these boxes.  And sometimes, for some of the studies, I actually manipulate people's sense of power.  So, there'll be two groups, a powerful and powerless group and they lift boxes and I compare the weight estimates that people give or I just look at like personal sense of power which is more like a trait power.  I try to see the relationship with that and with the weight estimates that people give again.

Chris -   So, we're going to look how you manipulated people's sense of empowerment in just a second.  So, the initial finding is that people who feel they're less powerful would judge a box which is a standard weight to be heavier than someone who is pretty pumped up feels that they are already pretty much in control and in pole position socially.

Eun Hee -   Yes.  So, about the manipulation that we've used...

Chris -   How did you do that?  So, you take someone and you make them feel powerless.  It doesn't seem straightforward.

Eun Hee -   All powerful for both.  So, we used two different procedures.  So, it's been kind of established in the literature of psychology and especially in social power.  So, first one we've used was this manipulation called posture manipulation.  So, we either tell them to sit in a way that's quite expansive.  So like they take bigger space on this nice ergonomic office chair.  So, I ask them to put their arms in the armrest, on the desk next to them, and ask them to cross their legs.  So for them, I think then that's for them to feel powerful whereas in the powerless condition, I would ask them to sit in a more constricted posture.  So, I ask them to put their hands under their thighs and put their legs together.  Yeah, that's how I did it for the posture manipulation.

Chris -   Did you explore with them when they were adopting those positions, whether they genuinely did feel more powerful or not?

Eun Hee -   We don't do that because it usually happens - what we think happens - unconsciously, so they're not actually aware that their sense of power changes.  Also, they're not aware that the sense of power and the weight box lifting is anything to do with it.  So, we are trying to see the unconscious influence on their weight estimates that they give.

Chris -   People who feel more socially empowered or less do judge the mass of the box to be different, do they?

Eun Hee -   Yes, different.  So, we found statistically different weight estimates that they give in these two groups and also three groups as well.  We had a neutral and control condition.

Chris -   How did you account for the findings?

Eun Hee -   In terms of mechanism really, we think this is like an adaptive mechanism that's evolved in us.  So for example, we know powerless people live in uncertainty and scarcity of resources.  So, maybe the exaggerated perception by powerless people might prevent them from taking further actions, exhausting all their limited resources.  So in a way, this will be adaptive.

Chris -   How might I apply this in my own life then?  If I go around taking up lots of desk space, does this make me feel better?  

Eun Hee -   I think it does definitely and one thing I think everyone should know from this research is that this relationship happens automatically.  They're not aware of this happening.  So sometimes, just because you feel quite low in the sense of power, you might be prevented from putting 100% effort into something that you're doing.  This will be disadvantageous in some situations.  So, I think if you're aware of this link, at least we're not going to let that happen.

Chris -   If you feel stronger physically, does that then rub off on you socially?  Do you also have a sense of social empowerment anyway because you feel stronger physically?

Eun Hee -   Well, I've never felt about that.  So, that's the other way around.  But one thing I know is, if you think about the whole relationship between posture and their sense of power, how posture actually manipulated this sense of power socially, so maybe in that way, you're feeling like physically powerful could maybe lead you to feel quite powerful in like a social sense in that case.

Chris -   Eun Hee Lee from Cambridge University.

Picture of a Truetone brand old-fashioned radio

16:00 - 100 years of radio

We take a look back at the last 100 years of radio...

100 years of radio
with Colin Smithers, Geoff Varrell, Steve Haseldine, Nigel Linge, Andy Sutton

We open our ears to Colin Smithers, Chairman of Plextek Group. Geoff Varrell, Director at RTT Oline. Steve Haseldine, Chairman of Deaf Alerter. Nigel Linge, Professor of telecommunications at the University of Salford  and Andy Sutton, Principle Network Architect at EE, at the Wireless Heritage SIG in Cambridge.

Ginny -   Radio was invented in the 1880s, but it only began to Picture of a Truetone brand old-fashioned radiobe put into practical use at the start of the 20th century. It wasn't initially used for broadcasting but instead to send messages between businesses and governments using Morse codE. colin Smithers...

Colin - But very quickly then it was socially important so reporting on yacht races started to happen as early as 1900, but not really suitable for broadcasting.

Ginny -   In fact the first broadcast radio stations weren't established until the 1920s.  Families would spend their evenings together gathered around a wireless and this was the Golden Age for radio.  But in 1939, the second world war hit. Radio became not just a form of entertainment, but a vital weapon for politicians. Geoff Varrell...

Geoff -   Well I think it's a mixed blessing because both for Britain and Germany and Italy, wireless broadcasting, of course fuelled nationalist identity.  It was the clash of those nationalist identities that actually caused the second world war.  Actually, it was Winston Churchill's war-time broadcasts that were tremendously important in terms of keeping the sort of British morale and I think radio broadcasting was essential to winning a war.

Ginny -   In the decades after the war, radio technology made some important advances.  Steve Haseldine...

Steve -   Well, the biggest change really was the move from the old valves to transistors and its created circuits.  So, radios went from being devices that were stuck in a room to being portable and anywhere in the house.

Ginny -   Radios became smaller and cheaper.  Meaning, many households could afford more than one.  Rather than the whole family gathering around a single wireless, younger and older members could listen separately. This opened up a whole new market of radio listeners.

Steve -   What really changed the whole scene, was in the 1960s, where you got a number of pirate radio stations. But more importantly, the music they played was for a much younger audience. It took a few years, but of course, the BBC then reacted and Radio 1 was established and it never look back...

Ginny -   Although invented in 1933, FM radio really took off in the second half of the 20th century.  The frequency band was broadened, allowing national coverage.  So, many BBC stations moved from AM to FM.  Nigel Linge...

Nigel -   As you drive around the country, of course, you are effectively picking up a slightly different frequency.  To aid that, they developed a radio data system, RDS.  In fact, the BBC pioneered the development of RDS.  Most people would think of it today as the thing that brings the traffic reports up, but it was actually brought in to help tune the FM stations as you move around.  The higher frequency also means you have shorter aerials as well.  So, portable devices became a lot more popular.

Ginny -   But FM's dominance didn't last.  In the 1990s, digital radio was developed and began to take over.  Now of course, many of us don't tune in at all and instead, listen to our radio programmes over the internet.  Andy Sutton...

Andy -   We did find during the period with GSM devices, global system for mobile communications or 2G, that we started to integrate FM radios into the actual mobile phone itself.  Nowadays of course, we tend not to do that and would rather take streamed content over the digital cellular network itself into the device.

Ginny - Thanks to all of the rest of the speakers at the Cambridge wireless conference. It will be interesting to see where radio goes in the next hundred years. Hopefully we'll still be here, well probably not me but some other naked scientist.

Chris - Do you know everyone said, as the buggles sang, 'video killed the radio stars' and it didn't quite work out like that and when the internet came along everyone said the internet would kill the radio and it's this enduring medium. I think it's due to the audio dimension and you can do other things while you listen which you can't do with other media. If you're watching a television programme you've got to watch it, whereas if you're listening to the radio you can cook the dinner while listening.

Ginny - Exactly. It's also so instant as well TV programmes take a lot longer to make so you don't get such instant news as we do.

 3D model of an influenza virus particle. Each virion measures about 100nm (1/10,000th mm) in diameter; the envelope bears molecules of haemagglutinin (blue) and neuraminidase (red) and encloses 8 ribonucleoproteins (RNP), which encode the viral...

20:42 - New flu: H10N8

A new fatal strain of flu has been identified in a patient in China...

New flu: H10N8

3D Model of an influenza virus particle.A new fatal strain of flu has been identified in a patient in China.

Documented in the current episode of the Lancet medical journal, the H10N8 bird flu virus was recovered from a 73 year old woman in Nanchang, China, in November 2013.

The patient presented with a cough and fever, which began about 4 days after a trip to a poultry market where the woman had purchased a chicken.

Despite treatment with antiviral agents, and even donor antibody, the patient died from respiratory failure 9 days into her illness.

Influenza virus was grown from diagnostic samples collected from the woman during her time in hospital. The genetic sequence of the virus revealed that it was of the subtype H10N8, which has not previously been recorded in humans.

The analysis also showed that the coat proteins of the virus, comprising the H and N molecules, were from two different bird flu viruses, while the internal genes, which control how the virus grows and replicates itself, were from an H7N9 virus similar to the one found circulating in China in 2013.

These findings suggest that this new H10N8 agent represents a new  "reassortant" formed when a mixture of viruses juggle their genes, producing a hybrid.

The Nanchang City public health team, who authored the present Lancet report, speculate that the woman picked up the infection during her trip to the poultry market, although follow-up studies in the area have so far failed to identify the source.

Reassuringly, none of the people with whom the patient had contact after the onset of her illness picked up the infection, and tests show that the novel agent is sensitive to the antiviral Tamiflu.

More worryingly, the Chinese team conclude their paper by reporting a second, more recent death from H10N8 on 26th January 2014, highlighting that the new virus appears to be minimally pathogenic in poultry, which could enable it to circulate for longer before its presence is detected, and pointing out that the first fatal case of H5N1 in 1997 preceded the next 17 cases by at least 6 months...

A plate of cooked pork chops. Photo courtesy of Stu Spivack

23:39 - Science of Sustainable Living

Examining Chris' shopping bag to find out the carbon footprint of his weekly shop.

Science of Sustainable Living
with Julian Cottee, Good Food Oxford

On to our main topic now and yesterday Cambridge hosted a conference discussing the environmental impact of the weekly food shop, and whether we can reduce it? To find out more we're joined by one of the speakers from the conference Julian Cottee from Good Food Oxford.

Chris - Hi Julian, So what is Good Food Oxford?

Julien -   Good Food Oxford is part of the UK Sustainable Food Cities Network.  So, it's our contribution as a city to creating a more sustainable food system starting with businesses and organisations and citizens in our own town.

Chris -   So, why wouldn't food be sustainable?

Julien -   Well, we know now that the food system as a whole is a major contributor towards greenhouse gas emissions globally for something like 20% or 30%, depending on how you measure, of our total global greenhouse gas emissions come from the food system and that's all the way through from production to processing, the transport, to even cooking in our own kitchens and industrially, and waste in the end of life of that food system.  So, it's a pretty major bit of the emission total.  There's also a whole lot of other associated environmental costs on land, water, and energy use, as well as impacts on biodiversity.  So, it's really one of the main impacts that we as human beings have on the planet.

Chris -   But at the same time, we have to eat.  So, are we not therefore obliged to have some kind of food footprint, regardless of what we choose to eat?

Julien -   Yes, that's absolutely true.  Everything we eat, it has to be produced somewhere.  It has to take up some piece of land that needs water to grow.  There are other inputs into that system that has impacts globally, but the choices that we make about what we eat have a huge impact on what that footprint is.

Chris -   Well, I've been shopping.  I've got my shopping bag here.  So, I'm just A plate of cooked pork chops.going to pull a few things out of my weekly shop and I thought you could perhaps tell me whether I get sort of nil points or whether actually I've made a good choice.  Okay, so the first thing I've got in here because I'm lazy, I have a bag of salad.  Is that a good food choice or a bad food choice?

Julien -   On the face of it, this seems like a pretty good choice because salad growing is mostly done in this country and Europe, so it's not being transported a vast distance.  The land and energy and greenhouse gas footprint of that product is also not huge.  So, a tick there.  One thing that might concern is about your choice of salad, it's been in the press a lot recently about waste.  Now, globally, around a third of food that's produced is wasted and the figure to things like salad is even higher than that.  Tesco last year published - the first UK supermarket actually to publish their food waste figures and they revealed that about 68% of all the salad that is produced for them is wasted.  So, more is wasted than actually is getting eaten, and that in itself fits into a bigger issue of food waste within the system.

Chris -   Julien, I promise to eat all of these bag of salad.  The next item in my bag, I've got some pork cutlets in here.  I don't know where they've come from, but they have a tractor image on them, so they look like they're presumably home-grown.

Julien -   A red tractor.

Chris -   Yes.

Julien -   Yeah, that's British production.

Chris -   So, is that good or bad?

Julien -   Well, it's pretty good.  We've learned recently that actually, the impact of transporting our food may not have quite as big an impact as we've thought in the past.  But it's still a good idea to eat from as close as possible.  That's pretty good and obviously, supports the UK economy, we've got to think about with other things as well environmental impacts.  But generally, meat is one of the biggest contributors to greenhouse gas emissions especially lamb and beef because they're ruminant animals and release a methane which is very potent greenhouse gas.  So, pork may be a little bit better on that count because they're not ruminants.

Chris -   I'm redeeming myself mildly.

Julien -   I'm very thankful.

Chris -   Thank you.  Given that we've identified these problems and my shopping bag is not blameless, what can we actually do?  What are you trying to do in Oxford for example that we could also mirror in other cities which will reduce the impact of what goes into our shopping bags?

Julien -   What we're trying to do first of all is to work out what the current situation is in a city like Oxford because the food system is quite complicated.  There are lots of interactions.  Obviously, we have to think not just about our environmental impact, but also, all the other parts of our economy, the impacts of equity in the food chain, about our food culture and what's tasty.  We got to think about all those things linked together.  So, what we're trying to do is get a handle on that by doing a process called food printing which is food foot printing basically to work out where in the system most of the impacts are coming from and therefore, where we can make the best impact, where we can put our resources to best use.

Chris -   And hopefully, ultimately inform the consumer which I hope will then lead to their change in their behaviour.  Julien, thank you very much.  It's Julien Cote.  He's from Good Food Oxford.

Ariculated Lorry

28:56 - The carbon costs of transporting food

We have to get our food from where it’s grown to where we buy it and to our houses. What can we do to try and reduce emissions?

The carbon costs of transporting food
with David Cebon, Centre for Sustainable Road Freight, Cambridge

We regard food miles as one of the most important things in reducing food's environmental impact owing to the amount of carbon involved in transportation. David Cebon is an engineer from the Centre for Sustainable Road Freight here in Cambridge who's working to reduce not necessarily the number of lorries on our roads, but their carbon emissions. Ginny Smith asked David why road freight is bad for the environment...

David -   Well, road freight is an essential part of modern living.  We can't live without road freight and we have lots of big vehicles, and they use a lot of fuel.  But only about 20% of the total road emissions from road, so cars are actually a lot worse than trucks in the end.

Ginny -   So, we have to get our food from where it's grown to where we buy it and to our houses.  What can we do to try and reduce the amount of emissions that we're producing in that process?

David -   The biggest part of emissions in that process comes from the last mile.  That means picking it up in your car.  The family car is the least efficient freight vehicle known to men.  It weighs 1.5 tonnes and it carries 40 kg of freight.  About 97% of the energy used to move that car goes in moving the car and about 3% in moving the freight.  If you have a big truck, most of the energy goes into moving the freight and much less into moving the truck.  So, the truck is much more efficient in fact than the family car.  The best thing to do is home delivery.

Ginny -   I actually in fact tend to order my food online and then you get a small - it's not exactly a truck, it's a van - delivering it; but I guess it's going on to other people and delivering other stuff as well...?

David -   It's doing a whole lot of deliveries around the town and it saves all of those car trips.  And all those car trips cause a lot of traffic congestion.  Traffic congestion in turn causes a lot of fuel consumption.  Everybody on the road uses a lot more fuel when the traffic is congested.  So, if you can have a very efficient home delivery, it's definitely a big part of what we can do.

Ginny -   Well, good to know that I'm being green, not just lazy!  So, is there anything we can do to improve - I know that you've said the trucks aren't as bad as the cars, but what can we do to make them even greener?

David -   There's all kinds of things that can happen that you can do to improve the fuel efficiency and the CO2 emissions of the freight system.  They're broadly in two categories.  One, kind of logistics things that how you arrange the system; and the other, I think, is to do with the vehicles.  There's all kinds of possibilities with the vehicles themselves.  In general, making the vehicles bigger is almost always better.  So, the example of home delivery is one clear one.  But if you can imagine that if you've got a delivery to a convenient store in town, if you have to drive two trucks instead of one, it uses a lot more fuel.  So, if you can have larger trucks going into city centres, perhaps out of hours so that they don't get mixed up with the bicycles and kids going to school, then that's the kind of thing we can do to really improve that efficiency.

Ginny -   That sounds like quite an easy thing to do, just make the trucks a bit bigger and send them in at night.  Is that something that's being done?

David -   There's been a lot of movement on that issue.  The Olympics was a good example.  In London, there were a lot more deliveries of freight at night.  You bump up against people who don't like to have big trucks driving around towns at night and that's a problem.  So, we've got a kind of a social dilemma - either we have more efficient vehicles running out of hours with the inconvenience perhaps of a bit of noise, or we have all the freight vehicles hitting the roads at 7:00am, which is what they do now - just when we're driving the kids to school and going to work - to beat traffic congestion time and park outside convenience stores and stuff.  So, that is a sort of a social problem we need to sort out.

Ginny -   And you've mentioned a few times that freight isn't actually the worst thing.  What is it that's causing the most carbon emissions through the sort of chain of food being grown to getting to our plates?

David -   Well, one other big issues, I think, is refrigeration: if you have a bottle of water and you refrigerate it. You bring it from France, and bring it on a boat and a couple of trucks.  The worst part of it is if you actually put it in the fridge and leave it in the fridge in the supermarket for a couple of days before it's bought: then it uses a whole lot more energy.  I think that the design of fridges in supermarkets is terrible.  If you go to a supermarket, for example, at the railway station not too far from here, you see all the workers in thermal clothes because it's so cold in the shop - the fridges are pumping out cold.  And there are heaters and fans. There are just piles of energy going into the shop, heat, and cold.  What we need is doors on fridges and a bit of sensible policy in supermarkets!

Ginny -   Thank you; David Cebon from the Centre for Sustainable Road Freight.

A refrigerator full of food...

33:54 - The costs of keeping it cool

Refrigeration may be a bigger environmental issue than transporting food around the country...

The costs of keeping it cool
with Graeme Maidment, London South Bank University

Chris -   Now, we've heard from David Cebon the gauntletA fridge being thrown down there.  We need doors on fridges.  They waste an enormous amount of energy.  In fact, some stats we've seen suggest that refrigeration is a bigger environmental issue than transporting food around the country and around the world in the first place.  Graeme Maidment is professor of air and refrigeration at London South Bank University and he's with us to give his perspective.  Hello, Graeme.

Graeme -   Hello, Chris.

Chris -   So first of all, what do you think of the comments that David is making about the fact that you go into a store and there's all these arrays of beautiful fridges full of products and they're all open?

Graeme -   Well firstly,  the comment I'd just like to come back on is the carbon emissions associated with refrigeration and air conditioning around the world.  We're a very intensive industry.  We do a lot of things for the society, producing lots of cooling for lots of applications.  And as a result, we use lots of energy and produce lots of carbon dioxide.  I think you quoted it like double that of air traffic.  We produced about 10% of all carbon emissions worldwide.  

Supermarkets are energy intensive.  There's about 7,000 in the UK and they produce or they use something like 3% of all UK electricity.  Much of that is for refrigeration.  Now, something like 30% to 50% of all the energy that goes into a supermarket goes into the fridge and David is right.  At the same time, that cold leaks out into the store and has to be offset with additional heating.  So, supermarkets, they use lots of the energy and there's lots of them.  In terms of the design of fridges, fridges have been around for many, many years. The issue of doors on cabinets has come up over the last 3 or 4 years and a number of supermarkets are using doors on cabinets.  But there's other things that we can do as well to reduce our emissions.

Chris -    I tell you what, I've found some things that have evolved in my fridge as well, but that's a different story.  Is it just because there's this perception that if you put a door on a fridge, people won't buy things?

Graeme -   I think there is some psychology associated with retail and I think anything that you put a barrier in its place or you don't display in the right way, so you don't get the lighting levels in the right way, it creates a potential marketing barrier.  So, I think retail is all about people seeing something and buying it impulsively.

Chris -   But these numbers that you've put on this are so staggeringly high that this suggests that we need some kind of policy, not just in Britain, but across the entire world to stop people doing what I would regard as flagrantly wasting energy.  Because if everyone has to put a door on their fridges, then no one is at a disadvantage relative to their competitors, are they?  And then the motivation and the impact is on people to develop fridges that people do want to open the door of and buy their contents anyway.

Graeme -   Yeah, I mean, doors on fridges are a good thing, but there's other things that we need to do.  We don't just need to hang on to a door on a fridge because if the carcass of the fridge and the components within it are the worst around then putting a door in it won't do anything.  If you think about your home, if you fit double glazed and leave the front door open...

Chris -   What's the point?  Indeed.

Graeme -   The double glazing doesn't have an impact.  So, there's lots of things that we need to do and there's lots of things that the industry in the UK are doing.  But there's others things we can do in terms of the storage practice.  I often go into the supermarket.  I see chilled naan bread and fresh pasta in the fridge.  Well, what was all that about?  Why aren't we buying the pasta from the dried pasta or the unchilled naan bread or wine?  Why do we buy chilled wine? So, there's lots of practices that we have to change I think to actually reduce our need for cooling in the first place.

Chris -   Can we get to a point that you were making though which is about the fridge itself?  So, irrespective of whether the door is left open or not.  What we put in the fridges has caused a lot of scientific controversy over years.  Not just the food, I mean, the refrigerants, the chemicals that make the fridge do its job because we had a huge hole in the ozone layer, owing to the fact that we were putting chemicals in these fridges that we're very good at keeping fridges cold, but they were very bad for the environment.

Graeme -   Yeah, ozone depletion was discovered in 1970s and the Montreal protocol was put in place to ban CFCs and the ozone layer has now recovered.  But the granddaughter of CFCs we found is a potent greenhouse gas so far.  It's called HFC, hydroflourocarbon and these are refrigerants that we're stealing away from now.

Chris -   So, in other words, by replacing CFCs with something that we thought would be better for the ozone layer, it's just an environmental insult in a different direction.

Graeme -   Well, it's had a different environmental impact and at that time, clearly didn't know, but it's come to pass now that the HFC refrigerants have got a high greenhouse effect.  So now, our industry is moving away from these, back towards some natural refrigerants and the sort of refrigerants that we use of things like carbon dioxide which is a greenhouse gas, but has got very low greenhouse gas potential - ammonia, hydrocarbons and things, a lot of those.  But all these refrigerants have got their challenges, which is why they stop using them many years ago.

Chris -   Well Graeme, I'm relieved that someone like you is on the case, if not just the fridge case.  Thank you very much.

Graeme -   Thank you.

Chris -   That's Graeme Maidment.  He's from London's South Bank University.  

Biodegradable waste in a trashcan.

40:15 - Wasting our food away

An astonishing 7 million tons of food and drink is thrown out in the UK every year. We dig into this waste.

Wasting our food away
with Marie-Ann Ha from Anglia Ruskin University

Ginny - Now, we've heard a bit about how we can reduce the carbon footprint of the food that we eat, but what about the food that we Biodegradable Wastedon't eat?  An astonishing 7 million tons of food and drink is thrown out in the UK every year.  Marie-Ann Ha from Anglia Ruskin University appeared at the Food for Greener Future Conference in Cambridge to talk about the impact of wasted food.  So, Marie-Ann, I mentioned 7 million tons of food and drink there.  It sounds like a huge amount.  Is that particularly large compared to other countries?

Marie-Ann -   I don't know how it compares to other countries, but it is an enormous amount.  For individuals, it works out at around 200 pounds per person per year of food that is being wasted.  This particular food waste is actually avoidable food waste as it's called.  So, it's food that is perfectly edible and it's being thrown out either because people think it's gone off or they've served too much.  Those are the main reasons that people decide to throw their food out.

Ginny -   So, people are taking perfectly good food and throwing it away.  Why do you think that happens?

Marie-Ann -   Chris mentioned that something had evolved in his fridge and this is one reason.  People do not look after their fridges properly and food tends to get pushed to back and forgotten about.  So that is perfectly edible food that goes off and once it gets that bad, you can't actually resurrect it.  There are also problems with food labels.  People do not understand when you have something that says that it's best before, fresh potatoes are a classic example.  These are actually edible for a long time.  I either grow my own potatoes or get them from a local shop, so I do not have any food label on my potatoes.  Potatoes do last a long time.  You need to store them correctly in a dark place and preferably, coolish, not necessarily the fridge,  and they will last for 2 or 3 months, but people do not understand this because the supermarkets put a label on that say, best before.

Ginny -   So, why do you think we have this big problem that people, I guess, pay so much attention to the labels rather than what's actually inside?

Marie-Ann -   This is actually part of the problem of sustainability.  People have forgotten skills and common sense of actually, when you look at a food or smell a food, you certainly know if it's gone off or not.  So Chris's evolving creature at the back of his fridge.  He would know from the look, the smell, and probably the noises it's making that it had definitely gone off.  But there are a lot of things like bread that might be slightly stale.  People throw that out instead of toasting it or making a bread and butter pudding or looking for alternate uses.  It's just people are no longer relying on their common sense.

Ginny -   Is this just a problem of people once they bought the food then throwing it away or is it happening earlier or up in the chain of produce as well?

Marie-Ann -   It's happening earlier in the chain as well.  We waste around about a third of our food that is actually grown on the farm.  It's destroyed before it gets to the farm gate and a lot of that is because of the perception of what food should look like, that it must be perfect.  Now, this has partly come through from previous EU regulations which said that we could sell either grade one or grade two, which were physically perfect that's a fruit or vegetable or meat.  That regulation has been changed, so we can now sell what is known for example as jam fruit, jam strawberries which is more or less slightly deformed.  People are still so used to seeing perfect fruit, vegetables in particular.  That's what I'm particularly interested in.  that they often do not choose the misshapen fruit and it will be left on the shelf.

Ginny -   Now, do you have any comments about our listeners who've told us about their dinner.  So, we've got someone making roast lamb, someone having rice which sounds very boring if they're just having rice.  We've got someone having toast and someone making curry.  Which of those would you say is the most sustainable dinner?

Marie-Ann -   If the roast lamb was a local lamb, then that would be very good.  I would hope they're having some fruit and vegetables with it or some vegetables with it.  Your father's home-grown leek sound to me like the most sustainable dinner we've had so far.  I presume he's got some local potatoes as well to go with it.  So, that's pretty good.

Ginny -   Great!  Well, thanks a lot Marie-Ann.  That was Marie-Ann Ha from the Anglia Ruskin University.

Are vegetarians better for the environment?

Marie-Ann - Really, the main question here is how was your food farmed. So, if organic farming is given as the most sustainable method of farming we have at the moment because it reintroduces nutrients back into the soil, all the nutrients that had taken out are put back. There are lot of regulations around looking after animals as well as fruit and vegetables and making sure that everything is as sustainable as possible. So, if you have an organic lamb that is fed correctly on grass outdoors and is fit, then it's just actually relatively sustainable beast whereas if you have a soya bean that has been grown for example in the Amazon and transported over, that is not particularly sustainable. So really, it's a personal choice and you really need to look carefully at the provenance of your food. Chris - David...

David - Well, I think it's a pretty good answer. I'll leave you that.

Chris - Are there any things that are specifically worse in terms of freight as far as vegetarians type things, moving vegetables around versus moving meat?

David - Well, things get refrigerated. Again, it's a problem. Things that come by air is a problem. Sea freight is very low energy. Air freight uses same miles per gallon as driving a car and that's very expensive.

A380 Airbus

How is food freighted into the country?

David - Not that I know of.

Chris - That's a very good point.

David - It's pretty good question. If it's very fresh, fresh flowers, that kind of thing, they have to be air freighted. There's no way they can come in the other way. But a lot of vegetables now can be picked green and don't necessarily have to be air freighted.

A food market with a wide array of different vegetables.

Foods lose nutrients during transport?

Chris - Marie-Ann, a question from Alice Danger (What a lovely name). "I'm interested in the loss of nutrients over the long commute. What things are not worth getting - what things if you can't have them fresh are not worth getting at all?"

Marie-Ann - Salad vegetables actually. Anything with a leafy, dark green leaf loses certainly things like vitamin C within 24 hours of picking. So, you really need to be looking carefully at anything that's too old. There's been a paper recently that found that even fat soluble vitamins, which we thought would stay for a while, actually breakdown after 4 months; that's in sweet potatoes. So, it's really looking carefully again where things come from and seasonality, so some things in season. Then it's likely to be fresher and better for you.

Ginny - So, what about eating fish? Is that better or worse than meat or vegetarians?

Marie-Ann - It's the same answer. It depends on how it's fished. So, Marine Council Certified fish is fished in such a way that it should protect fish stocks and allow regeneration within the oceans. It's again, transportation involved there as well because we are land loft in Cambridge so it's not that easy unless we have freshwater fish.

Ginny - What about refrigeration because I guess, fish goes off quite quickly, so you have to keep it quite well-refrigerated? So, does that make it worse?

David - Well, it's often frozen, isn't it? So, that's expensive on the refrigeration side.

Ginny - Is freezing things worse than keeping them refrigerated?

David - Well, it's a good question. It takes a lot of energy to freeze stuff. The temperature is much lower so you have a lot more leakage of cold. On the other hand, refrigeration in supermarkets is often or almost always has a lid or a door. So, that's a lot better from that point of view.

Chris - And if you look at keeping an animal alive, then that's got a carbon footprint associated with it too rather than it just being in a freezer. So, how does that work out?

David - Well, then you got to keep the water clean and cool and all that...

Chris - But equally, not just fish but meat in general. You know, it's easy to condemn a fish when it's got a lot of meat in it, but the meat is not respiring. It's not contributing carbon dioxide to the planet. It's not eating food and belching out methane because it's in a fridge. Whereas if you kept it as a live animal sustainably farmed, it is, isn't it?

David - If you could take the animal straight from the farm to your plate then you would miss out the whole refrigeration component wouldn't you? This would be rather difficult to do that.

Ginny - But also, freezers can be positive and that they reduce food wastes. So, when I cook too much dinner, I freeze some of it and have it another night. So, there's pluses and minuses I guess.

Marie-Ann - Yes, because it is one very good way of decreasing food waste, freezing any food that you see is getting up these by date. I keep my butter frozen because it doesn't go often go rancid that way.

 This image shows a display of healthy foods on a table. Foods include beans, grains, cauliflour, cantelope, pasta, bread, orange, turkey, salmon, carrots, turnips, zucchini, snowpeas, string beans, radishes, asparagus, summer squash, lean beef,...

Growing local rather than freighting?

It's quite important point in that though isn't there where if we could have growth in an area rather than ship it in from across the world. It would have lower environmental footprint, wouldn't it?

Marie-Ann - This is the whole question about seasonality. If we ate only our local seasonal fruit and vegetable at this time of year, Sydney and the UK, we're limited to brassicas. However, we do have a wide variety now. They have gradually been bread over the centuries. So, yes, it is a problem. We would not be eating avocadoes because they are not at all local. I think even with warmer winters, I don't think we will ever get to a stage where we see avocado trees growing in Cambridge.

A person picking his nose

50:05 - Is green mucus a sign of a bacterial infection?

Can you tell the stage and severity of your cold by the colour of your snot? A very important question for this time of year!

Is green mucus a sign of a bacterial infection?

Hannah - With post Christmas sniffles sticking around, what do you think about this one?

Sarah - Hi, Naked Scientists. My name is Sarah and I live in Tasmania, Australia. I'd like to know, is it true that if you have a chest or a head cold and then mucus turns yellow or green, this is a sign of a bacterial infection and requires antibiotics?

Hannah - So, can you detect the stage and severity of your cold by the colour of your snot? Over to Dr. Estee Torok, consultant in infectious diseases at Cambridge University.

Estee - Mucus is something that everybody has. It's produced by the goblet cells in the epithelial tissues which line the mouth, the nose, the sinuses, the throat, the lungs, and the intestinal tract. It acts as a protective blanket over these surfaces and prevents the tissues underneath from drying out. Mucus acts as part of the body's defence system by trapping unwanted substances like bacteria and dust before they get into the body. It also contains antibodies that recognise invaders like bacteria and viruses, and enzymes that kill the invaders that it traps in the protein called mucin. Even when you're healthy, your body turns out 1 to 1.5 litres of mucus per day and most of this trickles down your throat so you don't even notice it. However, there may be times when you do notice your mucus and this isn't usually because you're producing more of it, but because a consistency has changed. The things that can trigger these are respiratory infections or allergies, or contact with something that's irritating.

Hannah - In which case, can the colour of your snot signify whether you have a bacterial infection?

Estee - If you look at your mucus, normally, it's sort of quite clear. But at times, it can be yellow or green or even red or brown. When you get an infection and that can be bacterial or viral, the bugs damage the epithelial cells lining in your nose and throat and can cause inflammation. Your body responds by sending white blood cells called neutrophils to fight the infection and these neutrophils produce enzymes called myeloperoxidase enzymes that release oxygen and free radicals to kill the bugs or the viruses. These enzymes contain iron and the iron is what gives the mucus a green colour. So the neutrophils can die during the process of killing the infection and the green mucus therefore doesn't mean that it's necessarily a bacterial infection. It may be a viral infection.

Hannah - So, green snot can signify active immune cells giving off iron to help fight either a viral or bacterial infection. It doesn't necessarily mean you need antibiotics though. Thanks to Estee and also to Sarah for getting in touch with the question.

Chris - And our listener (Dan Manachuck) got in touch agreeing, saying the colour of phlegm has nothing to do with being a cold or flu having a bacterial infection on top. The green colour he says comes from dead cells and Steven on Facebook says, "If it's a pucker cold, it's usually is clear when you have the sneezing fits and that increasingly turns green as the cold is on the way out or going chesty." I'm usually pleased when it goes green when I have a cold because the end is usually neigh. With that cleared up, let's hear back from Hannah what we got in store for next week's question...

Hannah - Do you pick your nose with your left hand or are you a right-handed picker? Our next question is in from (Ray)...

Rey - Why are people either right-handed or left-handed? What possible benefit does that have over being ambidextrous? I find I'm right-handed, right-footed, and even right-eyed. When I wore a single muff headset on my job though, I preferred it on my left ear and not my right. So, that's a bit of a question. And do animals also display handedness?

Hannah - So, left or right-handed? Are other animals like this? Does it scramble your brain if you mix your left or right feet, arms and ears up?


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