Concrete concerns, and pharaoh de toilette

Plus, how much of a brain boost will free school meals provide?
08 September 2023
Presented by James Tytko


Aerial view of square spiral staircase with metal mesh


In this edition, can civil engineers help rescue the UK’s crumbling schools and hospitals? Also, new initiative that is hoping to improve the treatment of sepsis, and how the scent of ancient Egypt has been replicated in a Danish museum...

In this episode

Aerial view of square spiral staircase with metal mesh

01:04 - Is RAAC a safe building material?

Some engineers argue it can be useful in construction projects, if used properly...

Is RAAC a safe building material?
Chris Goodier, ISE, Loughborough University

Reinforced autoclaved aerated concrete - or RAAC, for short - was used as a cheap, lightweight building material between the 1950s and 1990s. Many public buildings across the UK contain it - but questions have been raised this week as to its safety. Some schools containing RAAC have been forced to shut their doors over fears that it poses a risk to children and their teachers. Hospital bosses have also warned that they are ready to evacuate workers and patients in the event that any weakened concrete shows signs that it is at risk of collapse.

Chris Goodier is a professor in construction engineering and materials at Loughborough University and has been conducting research on RAAC.

Chris G - RAAC is actually quite well named in that every letter is important. So it's reinforced - it's got steel reinforcement in it - and that's what gives it the structural capacity or the strength. It's autoclaved, which means uniquely it's baked at pressure and temperature in an oven when they make it. Aerated, it means it's got air in it, which makes it lightweight and a good insulator. And it's concrete, so there's nothing particularly different or fancy or strange about it from a concrete point of view. It's got cement in there and it's the cement that makes it hard.

James - You would suggest that it has some particular weaknesses as opposed to traditional concrete when it comes to exposure to the elements. And that's the root of why alarm has been sounded in some of the public buildings in this country.

Chris G - Yes, to a degree. So I probably need to set a couple of things straight. So you are right on that point. Because it's aerated, it can soak up water more than traditional concrete. And if left unattended or unaddressed, it can get to the steel inside sometimes and start to corrode that. It's a very low strength compared to traditional concrete and that is fine. So when you're designing it and you're building it, you know it's got low strength. It's the steel reinforcement that gives it the strength. So the fact that you can crumble it and break it quite easily is fine. Similar, I describe, to wood and timber, which we build lots of our homes out of. You can break a piece of wood over your knee if it's thin enough. The other thing is the 30 year design life, this is also something that isn't true but has got out there in everyone's consciousness and they're talking about it. No building lasts forever and no building material lasts forever; steel, concrete, timber, bricks. So we design them with what we call a typical design life of 30 to 40 years. That means we expect, around the 30-40 year mark, we need to look after them, maintain them. And if we want them to last longer, probably remediate them, repair them, prolong their life a bit. This has kind of got out there that it lasts for 30 years and then at year 31 it collapses. But that is simply not true.

James - I think that's the key point, isn't it? It's not so much the issue with the material, but the way it's been used or left unattended. Why has it all come to a head right now and why are we scrambling to survey not just schools and hospitals, but now courts and even parliament?

Chris G - There's a couple of reasons. The country in general, and most countries, don't spend enough on maintaining their infrastructure and their buildings. The maintenance of a building is a fairly easy thing to reduce the budget on short term because, for the next six months to a year, people wouldn't really notice. If you do this year on year on decades, then you will notice. And instead of just spending a bit every year, it gets to a point where you have to spend a lot. And then we found in our research that, in some of the RAAC panels, the biggest worry is that they can look okay. So when you look up at the ceiling, that looks fine. You can't see many cracks, but it looks okay. But 50 years ago it was possibly manufactured poorly or installed poorly by the builders. Poor building is no new news story. Every country in the world, you'll find some builders who don't do it as well as they could. So this happened with RAAC and it's gone unseen and unknown about until now. But, in our investigations there is some RAAC out there that a structural engineer considers critically unsafe.

James - And you made the key concern apparent there, which is you can't always tell from looking at it. How do we address this in the short term or what's the timeline for when all that critically unsafe RAAC will be identified?

Chris G - Million dollar question in a way. Hospitals now are in a good place, but there's a relatively small amount of hospitals. Schools, 22,000 as we know, with a big variety of location ownership and building types. So that's a very different challenge. They're making progress. Maybe not fast enough, but they're getting there. But then you've got all the other government departments, including the Commonwealth office tomorrow, the MoD I talked to, you mentioned justice, police. I've been to an ambulance station that had RAAC in the roof. And then there's private sector offices and factories and commercial properties from the 60's and 70's. So, timeline, this will be years. I think we we're moving to a situation of living with RAAC as a country, learning how to look after it, because we can't get rid of it quickly and it'll be years before we probably get around the whole of the estate.

James - I think it's probably fair to say, you might disagree, that we've offered a lukewarm defense of RAAC as a building material. It's something that, in the right context, can be used very safely. But, it has stopped being used. You don't suppose it'll ever be making return as a building material or start being used again? Or maybe I'm ignorant and it still is being used,?

Chris G - I'll boldy say it never went away. We got worried about it in the 80's in the UK, but it's still manufactured and used all around the world. In fact, I'm reporting here from Prague in Czechia. So I'm attending the seventh international conference on AAC (autoclave areated concrete.) There's people all around the world here, including China, India, Indonesia, manufacturing RAAC and installing it now, still. Thousands of factories around the world. So it comes back to where I started. There's nothing wrong with it as a building approach. You design it properly, manufacture it properly, and install it properly, it'll be fine. Cut corners, cut costs, do it wrong, it can fail. Coming back to the UK, I think we've gone too far now with public perception that you'd have to be a very bold builder to try and do it because no one would want you to, I think.

Bacteria seen under an electron microscope

'Once in a generation' sepsis research project launched
Joanne McPeake, University of Cambridge & Emily Perry

Sepsis is a life threatening condition that occurs when an immune response to an infection turns on the body itself. It can cause damage to vital organs and it kills around 50,000 people in the UK each year alone. Sepsis has been in the headlines recently following a tireless campaign by the parents of a 13-year-old called Martha Mills, who died from the illness in London in 2021. So, what should we know about it, and attempts to tackle it? Will Tingle has been speaking to Jo McPeake from The Healthcare Improvement Studies Institute at the University of Cambridge and Emily Perry who survived sepsis - but is living with its long-term impact...

Emily - I had my second daughter in August 2019. I had an emergency caesarean section and then had to have some emergency surgery afterwards because of a haemorrhage. So I'd obviously had a fairly traumatic few days and you know, was feeling pretty unwell and pretty tired. But I was discharged from the hospital, went home. I kind of continued to feel almost fluey for a few days, a few weeks. But I just put it down to the fact that I'd had, you know, all this surgery, my body had been through a lot. And also I had a newborn and a coming up two year old. So life wasn't exactly relaxing anyway. And then one afternoon, about three weeks after Victoria's birth, I was feeling really unwell and things had gone kind of very downhill quite quickly. My sister was luckily staying with us at the time and I said to her, 'you know, I think something's wrong. I suddenly feel very shivery but uncontrollable shivering.' And my temperature shot up and I was really struggling to speak. My hands and my fingers were starting to go quite numb. I don't remember too much more after that. I remember being taken in to hospital. And then it wasn't really until the day after I was admitted that the diagnosis of sepsis came through. I was in hospital then for the best part of a week. I was given really regular IV antibiotics, paracetamol to keep the fever down. It took a couple of days for the shivering to stop and that was really frightening because I think I hoped that, once I got into hospital, the medication would be an instant fix. But it was a really frightening time wondering if I could care for my baby and if I was going to even survive it. But then after a couple of days, they found the right antibiotics that started to make an impact and I started to feel better. It's not just what happens when you're in hospital, it's those weeks, months, years that follow. I had to have therapy for PTSD and I've had ongoing health anxiety. I think it's very difficult when you've had terrifying and life-threatening things happen to you to have that belief again that things will be okay, and that something else like that won't happen to you. You lose your faith that things will be alright and that these things happen to other people and that's a very hard thing to move on from.

Will - So, Joanne, to try and help those like Emily, the James Lind Alliance is launching this 'once in a generation' survey to ask people with firsthand accounts of sepsis, what they want studies about sepsis to look into. What kinds of questions is this survey going to ask?

Joanne - So the James Lind Alliance is going to be launching a priority setting partnership. And this has really been spearheaded by sepsis researcher FEAT. So this priority setting partnership, and the most important word in that is partnership, aims to identify and prioritise the unanswered questions or kind of the evidence uncertainties that, as a community, they agree are most important. And this is so that we can feed into policy makers and health research funders to make sure that they are aware of the issues that matter most to the people who need to use this research. So people who develop sepsis, family members, clinicians treating them.

Will - What questions are you expecting? What do you think are the hot button issues that people are going to touch on?

Joanne - I think there'll be a whole host and, you know, sepsis has a big journey to it. So there's that initial part of sepsis. How do we recognize it quickly? How do we treat it quickly? There's then the part of the actual treatment itself. What's the right antibiotics to use and how do we identify what are the right antibiotics to use? And then it goes on to recovery. How do we improve outcomes? How can we help people thrive after developing sepsis and actually some of those wider societal issues. So actually how do we support family members as well? How do we help people reintegrate socially? How do we help people get back to work? How do we help people's mental health in the long term? So what I'm really excited about with this is I think there could be right across the continuum of care that we see these research questions coming from.

Will - Emily, if this survey had existed four years prior, how do you think it would have benefitted you? What sort of questions would you have liked to have asked?

Emily - I think it would depend very much on when you asked me. I think as I started to make my recovery, it was the obvious ones of 'why did this happen to me?' What made me susceptible to sepsis and where did it come from? And is there anything I could have done to have prevented it? Was there anything that anybody else could have done to prevent it? But then I'd say now, four years on, almost to the day actually, it's looking back and thinking, well this has been a four year journey and I wouldn't say I'm at the end of it. How could I have been able to help myself in those six months following? The year following? I certainly feel that sepsis robbed me of the first six months with my newborn daughter. And that's something I can never get back. And I was so anxious and so frightened. I felt like I couldn't live in my own skin. And anything that could have helped me to process what had happened and understood what had happened to make a recovery, both physical and mental, would've been so incredibly beneficial. And I hope that this will bring about a situation in the future where mothers such as myself, but also you know, all other patients who suffer from sepsis will have a better journey and a better recovery as a direct result of this survey.

Will - With this survey coming out and national sepsis week starting on September 13th as well as Martha Mills' parents coming out this week and asking for more power to get a second opinion. All of this is putting sepsis into the spotlight, but for a disease that affects so many people, it perhaps doesn't get the coverage that other similar illnesses do. I mean, what needs to be done to address this?

Joanne - So, I think it's just a constant awareness raising. And that sounds, you know, quite vague, but I think it is about education and it's about educating all of society, but actually educating our healthcare professional cohort as well. I think the challenge in around sepsis is that sepsis can often be interlinked with other illnesses. So for example, somebody going for surgery for a certain disease process but then develops sepsis after surgery so it becomes mixed up with other illnesses. And so I think that's probably why there's kind of less awareness of it. But I think it is about raising awareness at a local level about education. Young people need to know the signs and symptoms of sepsis because the reality is if we can catch sepsis early, we can improve outcomes because people get treatment quicker. And actually the process that can often lead to death can be prevented. So I think it is about education and I think it is about raising awareness of sepsis.

Emily - Yeah, I agree. I think that there's obviously so many different groups of people that are at high risk for sepsis. You know, they're, they're very young, they're very old people who've recently had surgery, new mothers. I think it's about identifying those groups and how to reach those groups. You know, I certainly think that there have been lots of mums I've spoken to who just had no idea that they were at higher risk from sepsis, from having a caesarean or from just giving birth. And it's having that information available, making people know the symptoms and you know, finding a way to reach those groups individually I think is really important.

An apple sitting on a stack of books.

16:27 - Free school lunch could cause improved grades

What you eat is as important as whether or not you've skipped a meal...

Free school lunch could cause improved grades
Greta Defeyter, Northumbria University

London’s mayor, Sadiq Khan, has announced that all children in the city between the ages five and eleven will receive a free lunch when at school. It’s thought that around four million children in the UK don’t always get enough to eat. The plan to provide a free lunch to primary school kids in the capital has been welcomed by many. This is how the top celebrity chef, Jamie Oliver, responded to the announcement:

Jamie Oliver - This is a great day. In one of the greatest cities in the world, it means that we have a chance to apply measurement and actually prove that this is something not just for Londoners, but actually that's really relevant for the whole school food system across the whole country based on, on evidence of it being a good bang for the taxpayer's buck. I'm really pleased.

So, how might a good meal help our performance in school? James Tytko spoke to Greta Defeyter, professor of developmental psychology and director of the Healthy Living Lab at Northumbria University:

Greta - When your stomach is empty, a hormone called motilin causes it to contract causing hunger pangs, and your blood sugar level dips and your stomach produces another hormone called ghrelin, which activates neurons in the hypothalamus region of the brain that tells you you need to eat. And that actually divides attention between the learning tasks that the child or the adult is engaged in. The other part of that is, whilst the brain weighs only about 2% of the whole body weight, it uses 25% of the total body glucose. In other words, glucose that's absorbed into the blood is distributed to the brain cells to provide energy to the brain. So it's logical to follow that children who have not eaten either before school or skipped their school lunch, who may well be from food insecure households, are not able to concentrate, and do not have sufficient fuel, inhibiting working memory and sustained attention that are essential for learning.

James - So that's the theory. I suppose the question that follows is what's the evidence base that that is what's happening in schools across this country and indeed the world?

Greta - There's numerous sources of evidence in terms of breakfast clubs at school. There's quite robust evidence that skipping breakfast is detrimental to children's learning. And that's probably because that research is relatively easy because you can do it outside of the school system and you've fasted the night before. So you can actually have really good controls on what food is in the body. Breakfast - breaking the fast, it's actually in the term itself. The complication in terms of school food is it also depends, as well as actually whether you eat or don't eat, on the types of food that you're eating.

James - It's so interesting. So being hungry, first of all is not good for attainment, but being full doesn't mean being full of the food that's best for learning. I mean, the phrase school dinners in this country evokes the historical image of turkey twizzlers and chips, what we now refer to as ultra processed food or UPF. These sorts of foods are unlikely to be good brain food.

Greta - Correct. So you need to bear in mind here that the main macronutrients of food are carbohydrate, protein, and fat and carbohydrates are the sugars and starches found in bread, cereals, fruits and vegetables, and are the main constituents of most breakfast and often most packed lunches as well. In recent years, attention has been looking at what we call glycemic index. So high glycemic index carbohydrates - as seen in foods such as white potatoes, white bread - are often also referred to as simple or quick releasing carbohydrates. And they're quickly converted into glucose which results in a rapid and high increase in blood glucose with a corresponding rapid decrease; the so-called 'sugar high.' Whereas low glycemic index carbohydrates, such as found in green lentils, apples, full fat milk, are often referred to as complex or slow releasing carbohydrates that provide a smaller initial increase in blood glucose and a much longer gradual decline. Now this is interesting because when you actually map the intake of either high GI food or low GI food, it actually maps well onto cognitive tasks. If you consume a food that has mainly low glycemic index carbohydrates, your performance doesn't increase as quickly on cognitive tasks; it's roughly about the same. But your performance is sustained for a much longer period across the school day compared to if you eat foods that are high in GI.

James - This has the promise, doesn't it, of being an extremely important leveler in that we can use the science you've outlined today to reduce the gap in attainment that we see between the poorest and richest kids.

Greta - Yes, exactly that. But we have to remember that these options aren't cheap. And so I think the question is more of a political question in some ways. I think the evidence suggests in terms of stigma, in terms of increased uptake of the scheme through universalism, reducing bureaucracy costs, etc.. And knowing that we have a large proportion of families that are living in what we call household food insecurity, the scheme makes sense and the data definitely looks promising. I think the problem is that the cost of rolling out such a scheme, and especially when schools are facing so many additional costs, such as crumbling concrete, is high. So that's really a politician's job.

Senetnay's canopic jar

What did Egyptian embalming smell like?
Barbara Huber, Max Planck Institute of Geoanthropology

Researchers at the Max Planck Institute have recreated one of the scents used in the mummification of an important Egyptian woman called Senetnay more than three-and-a-half-thousand years ago. Will Tingle has been speaking to Barbara Huber about what her team did, and some of the surprising components that were used in the re-enactment:

Barbara - We did a number of chemical analysis on samples we took from the embalming material. So we first sampled the remains of the lady Senetnay, took the samples to the lab, then extracted them and analysed them with instruments such as GCMS, which is gas chromatography, coupled to mass spectrometry and liquid chromatography, mass spectrometry. So what these techniques do is basically break down a substance, a mixture, into the individual molecules, and then based on these molecules, we could identify and recreate the original ingredients that went into the mixture.

Will - So what was in the original mixture then?

Barbara - It was a really, really rich composition of different substances. We found fats and plant oils, beeswax. Then also a number of different resins, for example, larch resin. Then we also found bitumen, which is an asphalt like substance and a resin, which is either coming from pistachio trees or from damas trees. And this was a very interesting finding for us because the damas resin comes from a tree which is exclusive to Southeast Asian rainforests. It was a very surprising finding for us because it's very far away from the usual realm of the Egyptian empire. So it kind of hinted to a really long distance straight connection already in the mid second millennium.

Will - That's extraordinary. It's a very exotic import for the time, isn't it?

Barbara - Exactly. Yeah, it's very exotic and also very rare for this time period. We have not found that in any of the materials from this time. It has been discovered recently in another mummification balm, but from almost a thousand years later. And so if this would indeed also be damas then we would have evidence for this kind of long distance trade relationship almost a thousand years earlier.

Will - The use of such a rare substance in the process of mummification therefore must imply that the person involved, whilst not being a pharaoh, was something of an elite member of society. It's almost like today people try to display their social standing by wearing expensive high-end fragrances.

Barbara - Well, yeah, this was also one of our questions because the context of of Senetnay is also quite extraordinary because she was the wet nurse of the Pharaoh Amenhotep II and she was also buried within the Valley of the Kings, which is usually only for the pharaohs. And so we already knew that she must have been important to the pharaoh and have a kind of high social standing. And so we were also really interested into looking into her embalming material and see whether or not her embalming reflects her high social standing. And then finding something like this exotic resin and also the complexity of the mixture really reinforced this understanding or this notion of her as a high status person.

Will - Of all the substances you've mentioned so far that you found were a part of this balming material, you have bitumens and resins. Obviously they're very good at embalming things because they go hard, but is it also, do you think, a coincidence or a happy accident that they cover up the smell of a dead body quite well?

Barbara - Yeah, that's an interesting side of it. I mean, a lot of these substances have very strong smells. You know, think about bitumen when like a fresh tar laid on the street, you really smell that, right? Or like the coniferous resins are really strong resins as well. So I think this is perhaps one of the aspects of choosing that. But then on the other hand, as you said, like the statue resin or the bitumen, they really go hard. They form like a layer that avoids the tissue getting moist. And also they have a lot of bioactive properties, so they're like antimicrobial, insecticidal. So they also avoid insects. So they have a lot of different properties that are really good for preserving the body for eternity.

Will - And you worked with a perfume manufacturer as well, didn't you, during this process? So any chance of it becoming something we find on the shop shelves?

Barbara - <laugh>, I don't know if this would be like a perfume you would like to wear, but, it was a very interesting process working with a perfumer because they have a very different perspective on the materials than like we as the chemists do.

Clock face

27:10 - What are the odds of this spooky coincidence?

The coincidences we observe and the ones we often don't...

What are the odds of this spooky coincidence?

James - Well, John, what a great question. We'll try not to let you down and I know just the person to help me. University of Cambridge statistician, David Spiegelhalter.

David - I mean, it's a beautiful story. I love it. I love it. We need to think of it, first of all, in terms of assuming the song is played - he's going to play that song at some time in the day. What's the chance of it matching in that way? Well, I mean, let's assume that he plugs into his earphones 16 hours a day. He could do, and that's about a thousand minutes, but it could be morning or evening. I'm going to allow that. So out of the thousand minutes in which this song could be played at that particular moment of the song, the first line, two of them, would have this match. So that's a one in 500 chance, which is low, but not ridiculously low. The nice thing is that he observed this and what that reveals is that actually for all the coincidences that occur and that we notice that are so lovely, there are vast numbers that occur and we don't notice.

James - We've kind of butchered his question somewhat because the reality is he's not listening to this song all the time, or he just happened to hit shuffle and this one came on. But to even begin to calculate the odds of that, we've got to consider things like how often John is listening to music and then crucially, I suppose, what songs he has in his playlist and how many of them even contain references to time?

David - Yeah. You've got 34 hours, let's say the song lasts three minutes or so. We don't know how often he goes through that playlist. And so to work out the unconditional probability of this event happening to him, we would need to have a lot more information. The other thing which you mentioned is, are there other songs that mentioned time? And what it reminds me of is a wonderful art exhibition called The Clock, which I saw at the Tate Modern in London a few years ago. And all it is is clips from film and television of segments that at some point will show the time: somebody will look at their watch, the camera will spot a clock on the wall, and that time is always the time at which the film is being shown. It's full of all sorts of really obscure bits of TV and film which just feature the right time.

James - Yeah. What an incredible project to have undertaken.

David - Oh, just the thought of sorting through vast amounts of old films is quite extraordinary.

James - Thanks to the University of Cambridge's David Spiegelhalter. 



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