3Q with Lydia Bourouiba: How has our knowledge of the coronavirus changed since last spring

January 9th, 2021MIT Civil and Environmental Engineering

Lydia Bourouiba is an Associate Professor in the Department of Civil and Environmental Engineering at MIT, where she directs The Fluid Dynamics of Disease Transmission Laboratory. Her research and contributions in 2020 led to a newer understanding of respiratory emission dynamics and had implications for mask and respiratory design, social distancing recommendations, and other public health interventions during and after the COVID-19 pandemic. Professor Bourouiba sat down to share insights gained from her research over the past year. Q. How has our knowledge of the virus changed since last spring and what has that meant for your work? A. Many [...]


Lydia Bourouiba is an Associate Professor in the Department of Civil and Environmental Engineering at MIT, where she directs The Fluid Dynamics of Disease Transmission Laboratory. Her research and contributions in 2020 led to a newer understanding of respiratory emission dynamics and had implications for mask and respiratory design, social distancing recommendations, and other public health interventions during and after the COVID-19 pandemic. Professor Bourouiba sat down to share insights gained from her research over the past year.

Q. How has our knowledge of the virus changed since last spring and what has that meant for your work?

A. Many things changed, and some didn’t. Most of the changes we have seen in terms of our knowledge are, in part, related to the pathology and the reaction of the immune system — how the virus interacts with the body is one of the keys for patient treatment.  Another aspect is the ability to develop vaccines currently being deployed. Compared to historical precedent, this was done in a very short timescale of one year. Even with the massive effort it took to do that, we’re not really going to see the level of deployment that we would want to see for probably another year. The last important piece we have learned relates to knowledge about transmission; we now know that SARS-CoV-2 is definitely not just transmitted via large drops over short distances as was originally claimed. There is a very important component of transmission that occurs through inhalation of what remains in the air after a cough or sneeze and there are a number of questions remaining about that and the environmental conditions that promote or inhibit such routes of transmission and how much certain locations or indoor spaces enhance such routes of transmission versus others. We know that the airborne route definitely contributes significantly to transmission, but we still need more information to understand precisely how and what biophysical mechanisms are at play. So, we learned a lot but there is a lot that we still need to learn if we are serious about improving future prevention and mitigation of the spread of this pathogen.

Q. People are now being vaccinated but it will be some time before society is safe enough to return to normal. With the winter months still ahead, how can people avoid spreading coronavirus in indoor spaces with poor ventilation?

A. We still have a long road ahead of us before the vaccine covers the percentage of the population that we need in order to prevent further spread and stop the pandemic. In the meantime, indoor spaces that are poorly ventilated are a major issue and improving those situations should be of the highest priority. This could require making full infrastructure upgrades if the means are sufficient to do so, but if not, there are low-cost ways to improve natural ventilation and localized filtration systems that are more affordable. Steps should also be taken to minimize the number of individuals that occupy such indoor spaces, making sure that those who are vulnerable are not in contact with others that are highly and actively connected and interacting with many others regularly. So, essentially applying high standards of control and mitigation with respect to occupancy, face covering, air and surface hygiene, and distancing remain critical. Wearing high-grade masks is also an option for individuals that are at particularly high risk. Finally, it will be important to enable full and sufficiently homogeneous air changes in rooms with poor ventilation by opening the windows and ensuring adequate patterns of air circulation at regular intervals, even in the winter.

Q. Is there anything we can learn from this experience to avoid future outbreaks causing such global problems?

A. First, we shouldn’t repeat the pattern of past epidemics or pandemics in which within a year a resolution of the COVID-19 crisis we would see a return to completely ignoring the issue of infectious diseases and risks of epidemics and pandemics of respiratory infectious diseases in particular. We must ensure that there is more investment in monitoring and prevention in addition to massive efforts in developing vaccines. We need to think more holistically. It’s not just about vaccine development because as you can see, even with a historic level of resources, coordination, and some of the biggest pharmaceutical companies of the world coming together, we still need at least two years in the best-case scenario before an emerging pathogen that causes a serious pandemic can be tackled with a vaccine. In one sense, we were lucky with SARS-CoV-2 because another virus could have transmitted just as easily but with a much higher death rate. We are currently experiencing a bad-case scenario, but it’s not the worst-case scenario and we know that these pathogens will keep emerging. We need a strong mobilization system for early detection information-sharing worldwide so that the very early cases for such new emerging pathogens are identified and information is centralized and can be used quickly. But we also need a chain connected to that, ensuring proper investment in prevention before we even know what the pathogen can really do and to ensure that a system is in place to minimize the risk of worst-case scenarios triggered by high-frequency transmission settings that we know can occur. That’s something that I think we really need to think about from a societal standpoint, and which would have a big impact in terms of not having entire areas of the economy shut down before a vaccine is deployed, if it becomes available. Such holistic investments in early detection and prevention of transmission would have a big return on investment because the economy would simply be much more resilient, even when facing new pathogen threats.

One other piece that is really important to touch on is the need for fundamental research; often it is not obvious early on what will become important when a crisis hits. It is thus critical to fund research that sometimes does not necessarily look ready for immediate application. The type of research I do and have started years prior to this pandemic was not particularly popular in terms of funding but ultimately a lot of the insights we gained were helpful in guiding key policies and implementing mitigation strategies. So, the importance of investment in fundamental science and early vision, even when it’s not immediately applicable is critical to also keep in mind because when we face new challenges, it is often the insights from such research become or drive part of the solutions.

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Looking beyond luxury: MIT researchers eye silk as a powerful tool in the fight against climate change and global food sustainability

December 2nd, 2020Uncategorized

According to the United Nations, the world has seen a rapid, seven-fold increase to the global population, leading to an important question in our quest to address human impact on climate change: how can we continue to feed everyone without devastating our natural resources? In the United States alone, the U.S. Department of Agriculture estimates that about 13.7 million households experienced food insecurity in 2019. Benedetto Marelli, a professor of Civil and Environmental Engineering at MIT, is willing to bet on an unusual source to help tackle these challenges around food insecurity and sustainability: silk. “We are wasting 30 to [...]


According to the United Nations, the world has seen a rapid, seven-fold increase to the global population, leading to an important question in our quest to address human impact on climate change: how can we continue to feed everyone without devastating our natural resources? In the United States alone, the U.S. Department of Agriculture estimates that about 13.7 million households experienced food insecurity in 2019. Benedetto Marelli, a professor of Civil and Environmental Engineering at MIT, is willing to bet on an unusual source to help tackle these challenges around food insecurity and sustainability: silk.

“We are wasting 30 to 40 percent of the food we are producing which means we are wasting 25 percent of the freshwater that the entire world consumes. Food waste is the third CO2 generator in the world behind China and the United States, so it has a big impact.” says Marelli. “On top of that, we are wasting food that can feed 1.6 billion people while 800 million people suffer from food insecurity – in the U.S. almost 10 percent of the population.”

Marelli studies the properties of silk to understand how the material can be optimized to improve the way food is packaged and stored in the hope of reducing waste. He is the cofounder Mori, Inc – previously Cambridge Crops – a company working to design silk-based products to extend the shelf life of perishable food, such as meat and produce . Marelli also recently unveiled a sensor using silk microneedles, designed to identify consumers when a product has gone bad, reducing the need for guessing that can lead to products being thrown out before they’ve spoiled.

Silk is a versatile natural byproduct harvested from silkworms made for their cocoons. Humans have coveted the material’s luxurious textile properties for centuries, but it only recently has silk has garnered interest as a preservative. Since silk is nontoxic to humans, it can be packaged with or even placed into food consumed by humans, but more importantly, like with a silkworm in a cocoon, silk actually works to keep pathogens out, protecting food from disease-causing microbes.

“Silk acts like a barrier for microbial spoilage, when you think about the cocoon, that’s what it does – it protects the silkworm from the environment,” says Marelli. “One of the problems we face is not only food security but food safety, especially food that has pathogens inside. Right now, you have several thousands of people in the United States die each year from food borne pathogens.”

In addition to the potential direct benefit for U.S. and global consumers, Marelli envisions silk as a cash crop that farmers can tap into for a regular source of income, while also helping to reduce the amount of food wasted each year. Because of the extremely short stage of the silkworm – 28 days from egg hatched to cocooning – harvesting the silk would allow farmers to count on a consistent monthly wage. Additionally, the mulberry tree that silkworms prefer for the environment to make their cocoons are relatively low-maintenance and do not require a lot of additional resources to grow, provided the right climate conditions.

“It is important to find solutions that can minimize the amount of inputs that we’re putting in agriculture and food production. At the moment we are using too much fertilizer, pesticides, too much water, so we need to be able to develop new agricultural practices, and inform the growers who are already doing a lot of work to modernize themselves,” says Marelli. “We need to provide them with simple tools which help them minimize the amount of inputs, which is also good for them because their costs decrease.”

Reducing our reliance on crops that require huge investments of resources to grow them isn’t just good for farmers living in traditional areas either  it opens up a new realm of opportunity where and when crops can be grown, which would shift the paradigm in how we currently think about farming in general. New techniques such as vertical farming and other alternative farming methods are becoming more common, charting a path forward for shifting production from land to cities as we move towards soilless agriculture. But for Marelli, sustainability is key metric to consider in any forward-thinking agricultural process, and this mindset continues to inform his approach to design and refine his silk technologies.

“When it comes to regenerating silk to make coatings, that is where we need to be sure that the process, we develop can be made sustainable at scale, not just in the lab,” says Marelli. “No matter what, sustainability needs to be part of the process.”

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Projecting climate change impact on malaria transmission in Africa

November 30th, 2020Uncategorized

For Elfatih Eltahir, malaria symptoms always began the same way: chills that eventually gave way to high fever, a pounding headache, and nausea that persisted until this cycle finally broke days later. First encountered at a young age and again throughout his college years, Eltahir, now a Professor of Civil and Environmental Engineering at MIT, only had about two weeks until symptoms would return to sideline him again. “This pattern became my norm to the extent that I stopped checking with doctors first, and often chose to go directly to the nearest lab to check for evidence of malaria in [...]


For Elfatih Eltahir, malaria symptoms always began the same way: chills that eventually gave way to high fever, a pounding headache, and nausea that persisted until this cycle finally broke days later. First encountered at a young age and again throughout his college years, Eltahir, now a Professor of Civil and Environmental Engineering at MIT, only had about two weeks until symptoms would return to sideline him again.

“This pattern became my norm to the extent that I stopped checking with doctors first, and often chose to go directly to the nearest lab to check for evidence of malaria in my blood,” says Eltahir. “From there, I would stop by a pharmacy to buy chloroquine injections and bring them home to my sister who is a doctor, to ask her for help performing the injections.”

Growing up in Africa and attending university in Khartoum, capital of Sudan, malaria was a shadow that loomed large over everyday life like most cities in that region. This formative early life experience ultimately shaped Eltahir’s decision to study the environmental determinants of malaria for much of his career. In his new book, Projecting the Impacts of Climate Change on Malaria Transmission in Africa, Eltahir combines his personal experience contracting and treating the disease with his work, using it as an example to better understand the nexus of climate change, health, and poverty in Africa.

“Using rigorous field research and advanced disease transmission modeling, we were able to understand how climate change will impact this disease, which is one of the major public health challenges in Africa, and we were able to identify which regions of the continent are going to be more impacted by the hazards from increased transmission of malaria,” says Eltahir. “When you think of disease impact, you have to think socioeconomic status too – poverty.”

The book, coauthored by former graduate students in Eltahir’s Research Group: Arne Bomblies, now Assistant Professor of Civil and Environmental Engineering at the University of Vermont, and Teresa K. Yamana, an associate research scientist at Columbia University, and Noriko Endo, Product Manager at Biobot Analytics, summarizes the results of their research, representing the culmination of nearly two decades of work. Mosquitoes carrying malaria thrive in wet, warm temperature that is not too hot. Using custom made computer models, Eltahir’s group predicted that in Western Africa, climate change may keep environmental potential for malaria transmission the same or slightly hurt mosquito populations as temperatures rise. But in parts of Eastern Africa where the climate is more temperate, impacts of climate change could lead to a rise in the ideal conditions for mosquitoes carrying the disease.

“Bands of warmer temperature are likely to creep up into the highlands of Ethiopia, pushing it into the sweet spot for mosquito breeding,” says Eltahir, who predicts that low-income residents of the area will be disproportionately affected by the disease. “Now, when people think of the main challenge of our times, which is climate change, there is more interest in the nexus of climate change, health and poverty. This is a big topic now, but something we started looking at fifteen years ago.”

For Eltahir, it is important not only for scientists to talk about the global effects of climate change, but also to illustrate how people will see those changes occur at regional and local scales, and most importantly, what concrete steps can be taken to mitigate the harmful effects of climate change.

“The main reason for writing this book, and doing the research, is to inform society of these impacts, and hopefully that would motivate effective adaption policies to climate change.”

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CEE Profiles: Building a community for all

Luke Bastian holds his Navajo cultural heritage close to him wherever he goes. The child of a German father and Navajo mother, Bastian spent a lot of time visiting his relatives living in the Four Corners region of Arizona and New Mexico. As a young child growing up in Arizona, Bastian’s Navajo culture had always been an important part of his life and he knew before ever setting foot on a college that he wanted to seek out a community of fellow students with indigenous roots. His passion for math and science eventually led him to Cambridge. A self-proclaimed “nerd” [...]


Luke Bastian holds his Navajo cultural heritage close to him wherever he goes. The child of a German father and Navajo mother, Bastian spent a lot of time visiting his relatives living in the Four Corners region of Arizona and New Mexico. As a young child growing up in Arizona, Bastian’s Navajo culture had always been an important part of his life and he knew before ever setting foot on a college that he wanted to seek out a community of fellow students with indigenous roots. His passion for math and science eventually led him to Cambridge.

A self-proclaimed “nerd” Bastian says he developed a strong interest in math from a very young age.

“One of my first memories is of my sister giving me addition problems to solve when I was like three or four, so I was trained from pretty early on to like that,” says Bastian, a senior set to complete his undergraduate degree in the department of Civil and Environmental Engineering. “I thought architecture was interesting because I liked designing buildings in The Sims game, but at a certain point I was like, I like math and science more than art and felt that civil structural engineering was more the way to go.”

Bastian has a particular interest in concrete sustainability; he credits MIT Professor Franz-Josef Ulm’s Mechanics of Materials class with first opening his eyes to the realities of concrete’s carbon footprint in the world and provided a lot of thought in the way of solutions.

“The big premise of the class was getting us to address how carbon-intensive concrete is and the huge problems posed by the construction industry with respect to global warming and climate change,” says Bastian.

But for Bastian, it was more than just simple interest that led him to the mechanics and materials track for structural engineering; infrastructure in the United States needs a lot of work, and problems are often particularly pronounced on reservations. On the Navajo Nation, he would see dilapidated structures and imperfect roads and still to this day, many Navajos lack reliable access to clean water.

“I figured that one, I am interested in this and two, it could potentially be a way to give back to my community down the line.” Says Bastian.

Armed with a passion for math and science and a desire to give back to his community, Bastian quickly fell in with the American Indian Science and Engineering Society (AISES) at MIT. AISES is a national nonprofit organization focused on substantially increasing the representation of American Indians, Alaska Natives, Native Hawaiians, Pacific Islanders, First Nations and other Indigenous peoples of North America in science, technology, engineering and math (STEM) studies and careers. The group was small when Bastian arrived as a freshman, only about seven members total – but Bastian says the group has greatly expanded in four short years. Bastian was elected president of the group in the fall of his sophomore year and quickly began working on ways to grow the community and its influence on campus.

“We had a good amount of budget from alumni and company donations – AISES is a nationwide organization that focuses on engaging Native Americans, pairing them up and helping them become more active in STEM fields,” says Bastian. Companies often reach out to the group to offer assistance finding jobs, but since AISES was until very recently the only native group on campus, it has served an important social role for the members as well.

Since Bastian assumed the role of president, the group has focused more of its effort on public events as well as trying to raise awareness for Native Americans and Indigenous peoples. The MIT AISES chapter has become an important leading voice advocating for change within the Institute, and was one of the major players involved in MIT’s decision to rename Columbus Day to Indigenous Peoples Day, which the Institute formally recognized for the first time, just this past October.

Additionally, members of the MIT AISES recently worked with local Wampanoag community members to develop a statement acknowledging that MIT rests upon the traditional territory of the  Wampanoag Nation. The land acknowledgement is an official MIT statement that can be used at public events.

“Being able to give back to my community and affect change within the Institute feels special and I’m glad to be part of such an organization.” Says Bastian.

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The New (Ab)Normal, by Professor Yossi Sheffi, details how businesses and supply chains may be changed forever in the wake of the COVID-19 pandemic

October 23rd, 2020MIT CEE, Uncategorized

When COVID-19 hit, it threatened the way of life much of society had become used to and challenged countries, governments and businesses to respond with ingenuity and technology. In his new book, The New (AB)Normal, MIT Professor of Civil and Environmental Engineering Yossi Sheffi provides an inside look at the ways in which business, supply chains, and the global economy worked to overcome the circumstances brought on by the outbreak, and how those responses could reshape the way companies operate and our way of life permanently. Sheffi has served as the Director of the MIT Center for Transportation and Logistics [...]


When COVID-19 hit, it threatened the way of life much of society had become used to and challenged countries, governments and businesses to respond with ingenuity and technology. In his new book, The New (AB)Normal, MIT Professor of Civil and Environmental Engineering Yossi Sheffi provides an inside look at the ways in which business, supply chains, and the global economy worked to overcome the circumstances brought on by the outbreak, and how those responses could reshape the way companies operate and our way of life permanently.

Sheffi has served as the Director of the MIT Center for Transportation and Logistics since 1992; he has written several books on logistics and supply chain management – but this book was his first attempt as his own publisher as well. The book sets the stage by taking readers through the early days of the pandemic outbreak and leads into what Sheffi calls the “finest hour” for supply chain managers and workers. Sheffi explains how businesses were able to position themselves to meet the unique supply chain management challenges posed by the pandemic.

“Flexibility is key, especially for companies that buy and sell all over the world. During the next year or so companies will face a “whack-a-mole” recovery, involving random flare-ups, shutdown and recovery around the world in random places in random times. Think about Spain – plants and manufacturing there is closing down as we speak. If you buy your raw materials, parts, or finished products there, you cannot get it so you have to quickly adjust. Companies have to be very agile.” Explains Sheffi.

The book also addresses misconceptions around the notion everyday consumer supplies have become unavailable during lockdown periods as governments closed manufacturing to contain the spread of the virus. As Sheffi puts it, with the exception of medical supplies, almost nothing consumers regularly buy is in danger of running out. And most of the spot shortages were due to headlines that exasperated these spot shortages into a crisis, such as the toilet paper saga.

“There was meat, maybe they didn’t have exactly the cut consumers were looking for, but they did have protein to buy. Toilet paper shortage was in regard to the very soft stuff that we are used to, but the second tier-grade paper was almost always available and now, you see it in stores and there is little problem,” Sheffi continues. “When we talk about critical supplies, such as medical supplies we will need to have inventories. However, we do not need years’ worth, even if the pandemic may last for years – you need it for three to five months until the industry can adjust. As we have seen, many companies started producing every needed item from ventilators to masks.”

Ultimately, Sheffi sees the problems brought on by COVID-19 as very similar to those posed by climate change: both are global problems that require global solutions. In both cases the world did not listen to the warnings and we are now facing the consequences. Sheffi also believes that in both cases the solutions are technological.

“In the case of the pandemic the world had turned to engineers and scientists to develop vaccines and pharmaceuticals. To deal with global warming, technology has already produced renewables whose cost is lower – in many cases – than carbon-based technologies. However, the ultimate solution will be in technologies that reduce the green house gases already in the atmosphere, not only in reducing the rate of emissions and changing behavior. Finally, the pandemic has shown that when the problems are dire, there is money to solve them. One can only hope that a fraction of the money thrown at the pandemic will be used to develop and scale appropriate technologies to fight global warming. When the world takes the threat of global warming seriously, we will find a solution that will not only mitigate but reverse the effects of global warming.” Says Sheffi.

Sheffi is hopeful that the shared experience of COVID-19 and the poor handling of the response will be a wake up call that will ultimately benefit our society in the future.

The New (Ab)Normal: “Reshaping Business and Supply Chain Strategy Beyond Covid-19” is available now on Amazon. Professor Sheffi will be giving a book talk to the MIT community on Monday, 10/26 at noon. You can register for the talk here.

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CEE undergrad shares internship experience with World Bank

Natalie Northrup '22 is an incoming junior in the MIT Department of Civil and Environmental Engineering. Working from home is a challenge. I made it through the end of spring semester and I will make it through another semester this fall, but working from home for the World Bank this summer has been a different kind of challenge. My work with the Bank was made possible by the MIT Washington DC Summer Internship Program (MITDC), a program run by the Political Science (17) Department. The program funds travel and housing for 10-20 MIT students who have in interest in science [...]

Natalie Northrup ’22 is an incoming junior in the MIT Department of Civil and Environmental Engineering.

Working from home is a challenge. I made it through the end of spring semester and I will make it through another semester this fall, but working from home for the World Bank this summer has been a different kind of challenge.

My work with the Bank was made possible by the MIT Washington DC Summer Internship Program (MITDC), a program run by the Political Science (17) Department. The program funds travel and housing for 10-20 MIT students who have in interest in science policy and are looking to work in Washington, D.C. In a traditional year, the student cohort attends seminars and networking sessions while in D.C. for their internships, and participates in a 12-unit class, split between spring and fall semester, to help provide context for their summer work.

The program caught my attention after an internship working with brownfield site remediation in the Rust Belt. During the internship I learned just how important environmental regulations are in maintaining good stewardship of the environment. Many of the companies we worked with cleaned up sites or installed systems because there were regulations or subsidies to promote those behaviors. This example of the importance of government regulation inspired me to look at policy as a path to greater sustainability.

With this interest, I applied for the MITDC program in January and by the end of February knew I was accepted. From there, I reached out to think tanks, congressional committees, and other organizations in the D.C. area, using contacts from previous years of the program and applying for posted internships. Through a connection made by a connection of the program, I ended up with a position in urban systems analytics at the World Bank.

Natalie Northrup’s remote workspace as she interns at the World Bank in Washington, D.C.

When the coronavirus came full swing to the U.S. the program decided not to cancel for the summer, but to have all internships and seminars take place remotely. Though it was great to still have a job for the summer, this news was really disappointing. This meant no more meeting other MIT students and UVA students (the summer programming is a joint effort between MIT and UVA) while we all lived together in dorms, no more walking around the Capital in professional clothing (passing as a VIP to anyone who didn’t get too close), no more watching the 4th of July celebration on the National Mall, and most unfortunately, no more workplace culture and networking opportunities.

This brings us back to my initial point: working from home has been a challenge. I thrive on human connection. Building relationships with coworkers and peers is something that brings me joy alongside the work I am doing. It creates trust that leads me to coworkers when I need a question answered or need help finding direction for the project. It gives me exposure to the many different paths I could take to bringing positive change to the world.

But alas, we persevere. In my position for the Bank, I am working with environmental indicators, traffic data, and industry data to analyze pollution levels in Romanian cities. With this position I have strengthened my data analytics skills, making the available datasets workable, identifying correlations, and presenting the results in illustrative figures. I have also had more responsibility for my work than ever before. The internship started with my supervisor presenting the dataset and telling me ‘Do something interesting with it.’ So, I brainstormed and then got started. Now, nine weeks later, I am working on a report on urban sensor networks that will be supplementary material for the urban policy being presented to the Ministry of Regional Development and Public Administration in December. The goal is for this report to aid the country of Romania in effectively using funds from the EU’s Green Deal while building a monitoring network that will accurately inform environmental and quality-of-life measures moving forward.

It has been a challenge working from home on a largely self-motivated project, but challenges are opportunities for growth and I can definitely say I grew as a scientist, employee, and student this summer

My interest in science policy is not short lived. After this internship, I am excited for future opportunities to combine my technical skills with policy goals to design a more sustainable future!

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