Marr studied engineering at Harvard University and graduated Summa Cum Laude in 1996. During her undergraduate degree Marr developed an energy efficient lamp. She moved to the University of California, Berkeley for her graduate studies, where she worked in the department of environmental engineering. Her doctoral research considered how ozone levels were impacted by transport, population and industrial development. Marr joined Massachusetts Institute of Technology as a postdoctoral researcher, where she worked alongside Mario J. Molina. At MIT, she collected data to better understand pollution in Mexico, joining a measurement campaign on board a mobile scientific laboratory. As part of the campaign Marr tried to track down Mexico's most significant polluters, following taxi drivers as they made their way around Mexico City. The research informed environmental policy in Mexico and was proposed as a means to protect the inhabitants of other over polluted megacities.
Research and career
Marr joined the faculty at Virginia Tech in 2003, where she established her own research group that investigates engineered nanomaterials interact with the atmosphere. Marr showed that when released into the air, engineered nanomaterials can aggregate with other matter to form structures of various sizes. Beyond nanomaterials, Marr has considered how airborne pathogens pollute the atmosphere. To Marr, airborne pathogens are self-replicating assemblies of nanoparticles. In 2013 she was award a National Institutes of Health New Innovator award to study virus transmission by bioaerosols. Her early research considered the spread of influenza, looking at the viral concentration in the air of aeroplanes and play centres. She showed that it was in childcare centres that the influenza viral load was highest, and it was the lowest in hospitals. In an attempt to understand these findings, Marr has studied the viral and bacterial microbiome in different environments. Marr has demonstrated that viruses were more active in very high and relatively low humidity. In an effort to establish the dynamics of these pathogens, Marr has developed sensitive, multi-layer sensors. The sensors include a custom-DNA that has been designed to immobilise specific viruses, which are subsequently bound to another DNA strand which can be attached to a gold nanoparticle for viral detection using Raman spectroscopy. Alongside virus transmission and nanomaterial – atmosphere interactions, Marr has investigated the emissions and transport of air pollutants. She was appointed the Charles P. Lunsford Professor of Civil and Environmental Engineering in 2018.
Covid-19
During the COVID-19 pandemic Marr studied airborne disease transmission of SARS-CoV-2. She believed that the virus could be transmitted via inhalation of air contaminated with SARS-CoV-2 aerosols. Throughout the pandemic, Marr provided advice to the general public about the transmission of airborne viruses, and how they interacted with and survived on surfaces. Marr said that she would be concerned about transmission of the virus in elevators, because they have little mechanical ventilation and are a confined space in which the virus may spread. After the Skagit County chorale resulted in 75% of the choir members falling ill with coronavirus disease, Marr told the Los Angeles Times that the event should be a "wake up call" to members of the public who thought social distancing was over the top. As for other mechanisms by which the virus may spread, Marr has remarked that there is no such thing as a "safe" distance to stay from one another. She said that infected runners may release more virus into the air than walkers, because they would be breathing harder, but that they would also create a more turbulent stream of air around them, which could act to dilute the viral load. She recommended that runners keep at least ten feet apart from other members of the public. In early April 2020 Marr told Chemical & Engineering News that she believed that face masks should be worn to prevent the spread of the virus. Marr predicted that the viral transmission may decrease slightly during the summer, but that the difference would not be particularly significant as people spend more time in air conditioned rooms.
Awards and honours
2013 National Institutes of Health New Innovator Award
2014 Virginia Tech Dean’s Award for Excellence in Research
