New study shows gap between rich and poor has increased more quickly in the US than in Europe

Wealth inequality in the United States has increased more quickly than in Europe in the last 50 years, partly due to significant rises in stock market prices, according to a new study from Imperial College Business School, published in the Journal of Monetary Economics.

They are calling for action to be taken by governments and policy makers in the US, to boost wages at the lower end of the market, control unemployment, and stabilise house prices.

Researchers from Imperial and the Paris School of Economics drew on new economic data from which they could build a database of the distribution of wealth for most European countries for the first time. This brought the data in line with the available US financial figures and allowed them to compare the change in both total household wealth and wealth inequality in Europe and the United States since the 1970s to the present day, as well as working out the reasons for those changes.

The researchers found that although both regions had a similar steady growth in total household wealth, the way the wealth had been distributed has been markedly different since the 1980s.

Dr Clara Martínez-Toledano, Assistant Professor in Finance at Imperial College Business School, and one of the lead authors of the study said: “From the 1980s we see a wealth gap start to emerge, where there’s a more dramatic change in the United States. The wealth that the top 1% richest people own in the States has undergone a significantly larger increase than the top 1% richest in Europe – in other words, the gap between rich and poor in the US became much more pronounced as wealthy Americans became even richer.”

To discover why this gap emerged, the researchers broke wealth down into three key drivers: differences in saving rates; wages; and capital gains rates.

During the decades surveyed, the research showed that house prices had gone up dramatically in both regions, as had financial asset prices. However, stock market prices had increased much faster in the US than in Europe.

Dr Martínez-Toledano continued: “Differences in the composition of these assets across wealth groups is key. The richest people tend to own financial assets such as stocks and bonds, while the middle wealth groups tend to have a house as their major asset. But even with a big growth in house prices in both regions, stock market prices were the standout distinguishing factor, with a huge jump in value of US stocks during those decades.“

Another important factor that can explain the wealth gap between rich and poor in the US is inequality of labour income, with the US economy showing a much bigger contrast in pay between the lowest and highest paid workers than the European economies over the same time period.

To document these findings, the researchers ran simulations that substituted the labour income inequality and asset price trajectories from France into the US figures. They found the hypothetical US wealth concentration levels were lower as a result of the smaller rise in labour income inequality and the larger rise in house prices relative to financial assets in Europe. The results were similar when they substituted the same figures from other European countries into the US data.

The researchers say US policymakers should prioritise job market policies that are aimed at boosting wages at the lower end of the distribution to reduce wealth inequality. They also call on central banks to play a key role in stabilising house prices.

Dr Martínez-Toledano explains: “Less equal societies have less stable economies. High levels of economic inequality can lead to economic and political instability. This is why action needs to be taken before societies become polarised.”

The new Distribution Wealth Accounts for Europe database is already available on wid.world for other researchers to build on this work, with the researchers planning regular updates to stay informed about the state of wealth inequality in Europe and the US.

The project forms part of a bigger international drive by the World Inequality Lab to provide more comprehensive public information about wealth and income inequality across the world.

Wealth inequality dynamics in Europe and the United States: Understanding the determinants is published in the Journal of Monetary Economics.

Split-second of evolutionary mutation could have led to mammals, says UCL researcher

A newly-published hypothesis suggests a momentary leap in a single species on a single day millions of years ago might ultimately have led to the arrival of mammals – and therefore humans.

Published in the Journal of Cell Science, Professor John Martin (UCL Division of Medicine) thinks a single genetic mutation in an egg-laying animal may have resulted in the first formation of blood platelets, approximately 220 million years ago.

In mammals and humans, platelets are responsible for blood clotting and wound healing, so play a significant role in our defence response. Unlike our other cells, they don’t have nuclei – so are unique to mammals, since other classes of animal such as reptiles and birds have blood clotting cells with nuclei.

Our platelets formed from megakaryocytes that mature in the bone marrow. When these megakaryocytes are released into the blood stream and reach the very high pressure blood vessels the lungs, they ‘burst’ apart, each cell releasing thousands of platelets inside the bloodstream.

The researchers suggest that millions of years ago a mammalian ancestor – possibly an animal related to the duck-billed platypus – underwent the very first formation of platelets, thanks to a sudden genetic mutation in its blood clotting cells that meant normal cell division did not take place.

If so, those much larger cells might then have been forced to burst inside the first animal’s blood stream, releasing their cytoplasmic fragments. These fragments proved to be more efficient at stopping bleeding, so if this mutation was inheritable, it would have given its offspring a major advantage through natural selection. An animal with this mutation could stem bleeding from fighting or wounds much better than its competitors, and so live longer.

Professor Martin, Professor of Cardiovascular Medicine at UCL, says: “Because of the uniqueness of platelets, it is reasonable to suggest that a unique event led to their origin. This was a radical, internal evolution occurring in a single animal, on a single day, 220 million years ago, and was then reinforced by natural selection.”

Professor Martin and his colleague Professor D’Avino (University of Cambridge) then suggest that this mutation ultimately led to the development, over 120 millions of years, to the placenta, allowing the foetus to be retained inside the mother for longer-term development and thus allowing evolution to achieve live birth. The ability to clot wounds is an essential element of live birth by means of a placenta, since the placenta splits from the female’s uterus during the birth process. The female would not survive birth and therefore not be able to suckle her offspring if she was unable to stem the bleeding.

In their paper, Professors Martin and D’Avino propose experiments that would support their hypothesis, including in vitro and in animal models.

“Without this critical mutation, we suggest mammals would never have evolved, and therefore human beings would not be around today”, says Professor Martin. “With this research, we’ve laid down a marker based on the available evidence – and we’re suggesting these experiments that will either support or refute our hypothesis.”

New therapy for bile duct cancer extends patients’ lives

A new personalised cancer treatment can radically improve the outlook for some patients with bile duct cancer, a new study involving UCL researchers has found.

The clinical trial – the European arm of which was led by UCL researchers – found that patients who were otherwise facing end of life care survived for up to two years when treated with the drug futibatinib. The results are published in the New England Journal of Medicine.

The drug targets a particular genetic alteration found in around 14% of bile duct cancers, called FGFR2 fusions. Around 300 patients a year in the UK are diagnosed with bile duct cancer with this genetic alteration.

There are very few treatment options for bile duct cancer and the survival is poor, with patients newly surviving on average for just 12 months. Although the cancer is uncommon, incidence is on the rise globally.

This international trial recruited 103 patients with bile duct cancer who had undergone at least one chemotherapy treatment, but whose cancer had become resistant. The patients’ cancer tumours had been genetically analysed to check that they had an alteration in a particular group of genes, known as fibroblast growth factor receptors (FGFR). The drug, futibatinib, is known as an FGFR-2 inhibitor, as it targets this genetic alteration.

When the patients were treated with futibatinib, the results were striking. The drug was more effective at reducing the size of the tumour, with the cancer shrinking by over 40%, compared to 25% with chemotherapy. The drug also produced modest side effects compared to chemotherapy.

Patients on treatment survived for up to two years, even though they had advanced cancer and had sometimes tried up to five other treatments before entering the trial.

European lead and senior author on the paper, Professor John Bridgewater (UCL Cancer Institute and University College Hospitals NHS Foundation Trust) said: “This is a gamechanger, which turns treatment for this group of patients on its head. Instead of treating them with the blunderbuss that is chemotherapy, which attacks healthy cells alongside the cancer, we can offer a truly personalised treatment that just targets a specific alteration within the cancer”.

“The benefits that patients saw in the trial were remarkable. It’s absolutely essential that patients with bile duct cancer get their cancer tested to find out if they have this abnormality. We can’t afford to miss one of these alterations: the difference they could make to treatment outcomes is dramatic.”

There are currently other FGFR inhibitors already in clinical use, including one called pemigatinib, which has been approved for use in the UK by the National Institute for Care and Health Excellence (NICE). However, existing FGFR inhibitors are known to be susceptible to resistance within the cancer. Laboratory tests have shown this is less likely to be a problem with futibatinib, as it targets the FGFR abnormality in a more specific way, and so is likely to be more effective than existing drugs.

Trials are already underway looking at the possibility of using futibatinib as a first line treatment in place of chemotherapy. Professor Bridgewater said: “The question these trials now need to answer is not whether patients should be getting this treatment, but when.

“Hopefully, this kind of genetically driven treatment will become the new normal for oncology. Personalised treatment has long been a buzz word in cancer, but this trial is the real thing – proving that it can be done and bring huge benefits to specific groups of patients.”

More effective protected areas needed to halt biodiversity loss

Protected natural areas of the UK are struggling to halt declines in insects and spiders that have occurred over the past 30 years, according to a new study led by researchers from the UK Centre for Ecology & Hydrology (UKCEH).

Nature reserves, Sites of Special Scientific Interest (SSSIs), Special Areas of Conservation and other forms of protected habitat have long been regarded as a key tool in conservation efforts to preserve and restore natural habitats.

But the new study, which collated nearly one million records for more than 1,230 invertebrate species between 1990 and 2018, suggests these protected areas are just as susceptible to the wider declines in biodiversity occurring across the country.

The authors found that protected areas were richer in species than unprotected areas of the country, but both areas have suffered similar rates of decline in native insects and spiders over the past 30 years.

Pollinators, such as bees and hoverflies, have suffered particularly severe declines, according to the findings.

The results suggest that while protected areas are helping to conserve valuable habitats and the species within them, they need more assistance to tackle wider threats posed by climate change, pollution and invasive species that are causing biodiversity loss across the country.

“We see parallel trends for invertebrates in both protected and unprotected areas,” said Dr Rob Cooke, an ecological modeller at UKCEH and lead author of the study. “It is worrying, as you would expect species to show more positive trends in protected areas.”

The declines found in the study equate to the loss of more than three species per decade for protected areas and less than two species per decade for unprotected areas.

The study, which is published in the journal Biological Conservation, used data from a number of different invertebrate recording schemes across the UK that contained observations of ants, bees, hoverflies, ladybirds, spiders and wasps. Dr Cooke, together with UKCEH colleagues Dr Francesca Mancini, Dr Robin Boyd, Dr Nick Isaac and researchers at the University of Sheffield, then examined changes in biodiversity through the study period.

They found there were almost double the number of rare species in protected areas compared to unprotected parts of the UK. The trends of these rare species also remained stable in both protected and unprotected areas, suggesting they were benefiting from conservation efforts. But the authors found strong declines for common species, especially in protected areas.

Dr Cooke said: “Protected areas are often designated specifically to help rare species. But the more common species appear to be falling through the cracks. It should serve as a warning as today’s common species can be tomorrow’s rare species.”

The researchers conclude that the large number of protected areas around the UK could play a bigger role in the future. Protected areas have supported some notable conservation success stories, such as the bittern, the ladybird spider and the chalkhill blue butterfly. But the authors suggest more can be done to ensure protected areas are benefitting all of the country’s biodiversity. They say evidence-based policies, targets and management focused more on the effectiveness, rather than just the coverage of protected areas, may be needed.

Dr Cooke added: “I think the positive thing we can take from this is that we have a clear opportunity to make protected areas better for biodiversity.”

COVID-19 increased the vulnerability of people living with obesity

Adults with obesity surveyed in the study reported that their mental health – which is known to be associated with weight gain – had deteriorated between the end of the UK’s first COVID-19 lockdown in July 2020 and September 2021.

The number who struggled to get access to affordable, nutritious food was also substantially higher among this group during the pandemic than was reported in the general population.

The findings serve as a warning about the potential impact of the rising cost of living on people with the disease, according to the researchers. They call for greater support for people living with obesity, both to help address the ongoing impact on their mental health and food poverty longer-term.

The research, which is published in the Journal of Human Nutrition and Dietetics, involved an online survey of 1,187 adults living with obesity in the UK about their mental health, food insecurity and loneliness.

Nearly half of the participants (47.3%) in the study reported that their mental health had grown worse over that period. Nearly a third (32.6%) said they had sought medical support for their mental health. A third (32.4%) reported experiencing moderately severe to severe depression.

Food insecurity – which was assessed using a questionnaire about food they had bought or eaten during the study period – also worsened for some, with 3.1% saying at times they did not eat for a whole day as they lacked enough money or food. Very low food security was identified in 8.1% – nearly three times higher than the levels seen in the general population before the pandemic.

Dr Adrian Brown (UCL’s Centre for Obesity Research), lead author of the study, said: “Our findings suggest that people living with obesity were disproportionately impacted at a time when mental health and food security was declining for everyone during the pandemic.

“We are now entering another period where we are seeing large numbers of people experiencing food poverty, and in some cases, making a choice between buying food or having the heating on. Our findings indicate that people living with obesity will need greater support.”

Obesity affects 28% of adults in England, 25% in Wales and 29% of adults in Scotland. Through the pandemic, people living with obesity were urged to shield themselves by avoiding close contact with others due to the increased risk posed to them by the virus.

Perhaps as a result, the researchers said, almost two thirds (61.7%) of those taking part in the UCL research said they had felt lonely between March 2020 to September 2021, with 27.4% reporting high loneliness – levels that were higher than those seen in other surveys of the general population.

The study follows earlier research by the same team that looked at the mental health of people with obesity during the first COVID-19 lockdown in the UK between March 2020 and July 2020.

Professor Rachel Batterham (UCL Medicine), senior author in both studies, said: “Adults with obesity are twice as likely to die as the result of a COVID-19 infection in England than those without, but our results show that poorer mental health has been another hidden health concern for this group of people.”

The latest UCL study also revealed that many of those living with obesity (79.6%) took active steps to potentially reduce their risk by making changes to their lifestyles. This included buying healthier food, doing more physical activity and eating a healthier diet.

Those with the lowest levels of food insecurity were most likely to buy and eat healthier food.

Despite this, the researchers raise concerns that the combination of COVID-19, the soaring cost of living and a potential reduction in government support due to a recent review of the UK’s Obesity strategy could have long term health implications for the country.

Professor Batterham said: “Poor mental health and food poverty are among the complex factors that drive weight gain. More emphasis is needed to address these if efforts to address obesity are to be successful.”

Dr Brown added: “Obesity is a complex, relapsing, long-term condition. The traditional view has been that we should ‘eat less and exercise more’. But this doesn’t take into account the biological, genetic, social and psychological determinants which all interact in someone developing higher body weight.”

Signal processing algorithms improved turbulence in free-space optic tests

New signal-processing algorithms have been shown to help mitigate the impact of turbulence in free-space optical experiments, potentially bringing ‘free space’ internet a step closer to reality.

The team of researchers, from Aston and Glasgow universities, used commercially available photonic lanterns, a commercial transponder, and a spatial light modulator to emulate turbulence. By applying a successive interference cancellation digital signal processing algorithm, they achieved record results.

The findings are published in the IEEE Journal of Lightwave Technology.

Free space optical technology wirelessly transmits data as light through the air around us – called ‘free space’ – for use in telecoms or computer networking. Because free space optical communication doesn’t require the expensive laying of fibre cables, it’s seen as an exciting development in bringing communications to places where there is limited existing infrastructure.

But because data is sent as pulses of light, weather conditions can cause problems. A bright sunny day or thick fog can diffract or scintillate the beam of light, creating turbulence which causes data to be lost.

The researchers simultaneously transmitted multiple data signals using different spatially shaped beams of light using a so-called photonic lantern. Turbulence changes the shape of the beams, often losing the signal if only a single simple shape is transmitted and detected, but by detecting light with these shapes using a second lantern, more of the light is collected at the receiver, and the original data can be unscrambled. This can greatly reduce the impact of the atmosphere on the quality of the data received, in a technique known as Multiple-input multiple-output (MIMO) digital signal processing.

Professor Andrew Ellis at Aston University said: “Using a single beam, when a single beam was transmitted, turbulence similar to a hot sunny day destroyed the signal 50% of the time. By transmitting multiple beams of different shapes through the same telescopes and detecting the different shapes, not only did we increase the availability to more than 99%, we increased the capacity to more than 500 Gbit/s, or more than 500 ultra-fast Pure-Fibre broadband links. ”

A project investigating the real-world applications of FSO technology is presently underway in South Africa, where researchers from Aston and Glasgow University are working with the University of the Witwatersrand in Johannesburg to attempt to bring internet access to communities living in informal settlements and schools in underprivileged areas.

The Fibre Before the Fibre Project, aims to provide the internet performance of a Pure-Fibre connection without the need to install cables. It uses a free space optical communication system that can link to remote sites using a wireless optical line of site signal to link to nearby fibre sources in more affluent suburbs.

Professor Ellis said: “Our role in the project is to look at the impact and educational benefit free space optics will have for the school children who will finally be able to access the internet.”

Mountain ecosystems should be prioritised in biodiversity policies

More action is urgently needed to safeguard the world’s precious mountain ecosystems, according to a University of York researcher whose policy brief is being presented at this month’s United Nations Biodiversity Conference (“COP15”) in Montreal, Canada.

Professor Robert Marchant is calling on national governments to put mountain environments at the centre of their climate change and biodiversity policy efforts and actions.

The UN General Assembly named 2022 the International Year of Sustainable Mountain Development – some 20 years after the first International Year of Mountains. But while some successes have been achieved in that time, Professor Marchant says national policy simply isn’t keeping pace with land use change, development, population growth and the impacts of climate change on global mountain systems.

“Twenty years on, climates are still changing, populations are still growing, and mountain environments continue to be developed and transformed – but what hasn’t happened is any corresponding establishment of sustainable policies,” he explains. “Government environmental and business policies are rarely joined up and we are seeing continued widespread land degradation in mountain habitats. This includes uncontrolled grazing, deforestation, or overdevelopment – and much of it is resulting from weak policies and changing tenure laws.”

Mountains cover around a quarter of earth’s land mass. They host about half the world’s biodiversity hotspots. They are a hugely important component of global water supply because they receive more rain than lowland areas, experience less evaporation at high elevations, and contain large stores of water as snow and ice.

Well-functioning mountain ecosystems are more resilient to climate extremes – they can buffer shocks such as high intensity rainstorms or prolonged dry spells – and are important stores of carbon and storehouses of biodiversity.

Despite this, mountains don’t receive the corresponding policy attention and investment from their national governments. They are particularly vulnerable to climate change and human interventions, which threaten their globally important ecosystem services.

For example, the area around Mount Kilimanjaro in Kenya is an area of high population density and rapid economic development. It has seen a major expansion in agriculture over the past twenty years, as land has been privatised and companies have realised they can drill deep boreholes in the land to extract water from the mountain’s aquifer.

Professor Marchant notes: ““Once you’ve paid for that borehole, that water is a free resource to you. But these services are provided by nature – and no-one is presently paying for either the water resources or for stewardship of that land. Asking companies to pay for this kind of service, by issuing controllable permits for example, would be a step towards treating our mountain resources with more respect.”

Professor Marchant and his co-authors are calling on countries to invest more in mountain ecosystem restoration activities, and to formulate effective climate change policies that consider the unique nature and resources of mountains. Also urgently needed is more international information sharing and data collection on mountain use, as well as better analysis of the current restoration initiatives taking place around the world.

He says: “We are hoping for some progress at COP15, but what is really needed is an international treaty or code of practice that accepts the value of our mountain ecosystems, and I suspect that is some way off.”

Brexit changes caused 22.9% slump in UK-EU exports into Q1 2022

Research by the Centre for Business Prosperity at Aston University has shown that UK exports to the EU fell by an average of 22.9% in the first 15 months after the introduction of the EU-UK Trade and Cooperation Agreement, highlighting the continuing challenges that UK firms are facing.

Building on earlier work funded through Aston’s Enterprise Research Centre, the researchers found that a negative effect on UK exports persisted and deepened from January 2021-March 2022.

According to the research, the UK has also experienced a significant contraction in the variety of goods being exported to the EU, with an estimated loss of 42% of product varieties. The researchers say this, combined with an increased concentration of export values to fewer products, has serious implications for the UK’s future exporting and productivity.

The authors are calling for an urgent national debate from politicians about the UK’s post-Brexit trade arrangements.

The researchers assessed the impact of the TCA, which allows goods to continue to be bought and sold between the UK and EU without tariffs in the wake of Brexit, by creating an ‘alternative UK economy’ model, based on the case that the UK had remained within the European Union. By comparing the model UK’s exports and imports with actual figures for the UK, they could accurately isolate the impact which the new trade rules were having.

“What we are seeing is the effect of Brexit on exports; and that is persisting. It’s not diminishing, and exports have yet to show signs of recovering,” says Professor Jun Du of Aston University. “Until this serious problem with exports is openly acknowledged and discussed, we won’t see any necessary actions being taken.”

Unlike exports, an initially significant drop on EU imports to Britain has recovered during the same period, suggesting that UK businesses and consumers have quickly adjusted to new rules. This stands in contrast to the persistent decline in UK exports, which the researchers believe is caused by more fundamental factors.

Professor Du said: “It seems that the UK can buy, but it can’t sell – and that’s reinforcing the problem of Brexit. A reduction in import bottlenecks might help exports to rebound, but this recovery is likely to be offset by the rising costs of imports.”

Researchers found that as many as 42% of the product varieties previously exported to the EU have disappeared during the 15 months after January 2021. This, they say, is principally caused by a large number of exporters simply ceasing to export to the EU, while the remaining exporters are streamlining their product ranges.

Co-author, Dr Oleksandr Shepotylo, says: “The product varieties that have disappeared are mostly those with low export value – we know this because the average export value increased as the number of varieties declined. These products are the ones typically exported by small firms or new exporters, or are exported to new markets. And It’s those smaller businesses that would normally export much more in future, as they grow their volumes and products – so that’s the UK’s future export pipeline being affected, which has bleak implications.”

Professor Du says: “The evidence we present here shows the real loss of Brexit, the overall competitiveness of the UK as a global trader. The considerable contraction of the UK trade capacity, combined with an increased concentration of export values to fewer products, signify some serious long-term concerns about the UK’s future exporting and productivity. Debate is essential so that the UK can start to address its current challenges. Of course, no one is suggesting going back into the EU, but there are collaborations, conversations and discussions that must be had. If the UK’s political leaders don’t acknowledge the facts, they are setting the course towards even longer-term problems.”

Less intensively managed grasslands have better soil health

Researchers have shown – for the first time – that less intensively managed British grazed grasslands have on average 50% more plant species and better soil health than intensively managed grassland. The new study could help farmers increase both biodiversity and soil health, including the amount of carbon in the soil of the British countryside.

Grazed grassland makes up a large proportion of the British countryside and is vital to farming and rural communities. This land can be perceived as only being about food production, but this study gives more evidence that it could be key to increasing biodiversity and soil health.

Researchers at the UK Centre for Ecology & Hydrology (UKCEH) studied 940 plots of grassland, comparing randomly selected plots which sampled the range of grassland management across Great Britain; from intensively- managed land with a few sown grassland species and high levels of soil phosphorus (indicating ploughing/reseeding and fertiliser and slurry application), to grassland with higher levels of species and lower levels of soil phosphorus. The plots were sampled as part of the UKCEH Countryside Survey, a nationally representative long-term data set.

The study counted the number of plant species in sample areas and analysed co- located soil samples for numbers of soil invertebrates and carbon, nitrogen and phosphorus levels.

Researchers found that less intensively managed grassland had greater diversity of plant species and, strikingly, this correlated with better soil health, such as increased nitrogen and carbon levels and increased numbers of soil invertebrates such as springtails and mites.

In the same study, the researchers used the same methods to examine the plant diversity and soil from grasslands on 56 mostly beef farms from the Pasture Fed Livestock Association (PFLA) – a farmer group that has developed standards to manage and improve soil and pasture health.

The researchers found that plots of land from PFLA farms had greater plant diversity – on average an additional six plant species, including different types of grasses and herbaceous flowering plants, compared to intensively farmed plots from the Countryside Survey. In addition, grassland plants on these farms were often taller, a quality which is proven to be beneficial to butterflies and bees.

Pasture Fed Livestock Association grasslands did not yet show increased soil health, but the research indicated that this may be due to a time lag between increasing numbers of plant species and changes in soil health, particularly on farms which have been intensively managed in the past.

Lead author Dr Lisa Norton, Senior Scientist at UKCEH, says: “We’ve shown for the first time, on land managed by farmers for production, that a higher diversity of plants in grasslands is correlated with better soil health. This work also tells us that the Pasture Fed Livestock Association members are on the right track to increase biodiversity, though it may take longer to see improvements in soil health.

“Grassland with different types of plants able to grow tall and flower is associated with improved soil health measures, and is beneficial for creepy crawlies below and above ground. Having this abundance of life in our grasslands can in turn support small mammals and birds of prey, and farmers have told us that they are seeing voles and mice in their fields for the first time.”

Dr Norton adds: “My hope for the future is that our grasslands can be managed less intensively – with all the improvements in plant and animal biodiversity and soil health that brings – but still remain productive for farmers.”

The study was published in the journal Ecology Solutions and Evidence today [25 November, 2022] and was funded by the UK Research and Innovation Global Food Security Programme.

Low-traffic neighbourhoods reduce pollution in surrounding streets

Low-traffic neighbourhoods (LTNs) reduce traffic and air pollution without displacing the problem to nearby streets, new research has shown.

The study by Imperial College London looked at three LTNs in London, to identify their impact on both air pollution and traffic within the LTN zones and in the surrounding area.

LTNs aim to reduce through traffic in residential areas, usually by the use of barriers which prevent cars from using certain streets, while leaving them open to pedestrians and cyclists. Many LTNs were put in place during 2020, to prevent an increase in vehicle traffic as people avoided public transport through fear of infection. However, they also provoked opposition, with critics claiming that LTNs increased traffic and pollution in surrounding areas.

The researchers studied three LTNs in Islington, one of London’s most densely populated boroughs, which were put in place during 2020. The team compared pollution and traffic levels at monitoring stations inside the zones, on streets surrounding the zones, and at control sites further away, using data gathered by Islington Borough Council. The LTNs – in St Peter’s, Canonbury and Clerkenwell – were put in place between July and September 2020. The team analysed data gathered from July 2019 to February 2021.

Because each of the LTNs was set up at a different time and not all monitoring sites gathered data continuously, averaging out the results between the three LTNs would not provide an accurate overall picture. So the team carried out a more complex statistical analysis to ensure other factors that might affect traffic volumes and air pollution at particular times – such as the Covid restrictions in place, school holidays or weather – could be taken into account.

Using this analysis, the researchers found that concentrations of nitrogen dioxide fell by 5.7 percent within the LTNs and by just under nine percent on their boundaries, compared to the control sites. They also found that traffic dropped by over half inside the LTNs and by 13 percent at the boundaries, compared to the controls.

Dr Audrey de Nazelle, from Imperial’s Centre for Environmental Policy, said: “This research effectively disproves the argument that low-traffic zones will necessarily cause an increase in traffic and air pollution in neighbouring streets. In the three areas we looked at, they reduced both traffic volumes and, significantly, air pollution both inside and on the edges of the zone. Alongside the other benefits of LTNs that have been shown in previous research – such as improvements in safety and an increase in walking and cycling – this makes a very strong argument in their favour.”

Co-author, PhD student Helen Yang added: “This is the first study to use a robust statistical approach to show the impact of LTNs on surrounding areas, and the results are really encouraging. We worked with a relatively small data set and further research is now needed to confirm these findings at a larger scale.”

The research is published in Transportation Research Part D.