“The world is our real laboratory”

Fire, earth, air and water. The research carried out by Dr. Athanasios Nenes covers all the elements – from microscopic to the global scale. Professor Nenes joined EPFL in September 2018 as a full professor of environmental engineering, and at the same time opened the Laboratory of Atmospheric Processes and their Impacts (LAPI) at the school. His team of 15 scientists spend their time collecting data in the field, conducting experimental research and running computer models to study cloud particles and assess the effects of air pollution on the climate, human health and our planet’s ecosystems.

After obtaining a chemical engineering degree in his native city of Athens, Professor Nenes earned a Master’s degree in atmospheric chemistry from the University of Miami and a PhD in chemical engineering from the California Institute of Technology (Caltech). He was appointed assistant professor at the Georgia Institute of Technology (Georgia Tech) in 2002, and was promoted to full professor in 2011 – a position he held until coming to EPFL.

Professor Nenes received the American Meteorological Society’s Henry G. Houghton Award in 2009, the American Association for Aerosol Research’s Kenneth T. Whitby Award in 2011 and the American Geophysical Union’s Atmospheric Sciences Section Ascent Award in 2012.

In 2016, he won a European Research Council Consolidator Grant for his PyroTRACH project to study air particles caused by fires. He serves as an affiliated researcher for the Greek Foundation and the National Observatory of Athens; he also sits on the United Nations’ Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection and is Deputy President of the European Geosciences Union’s Atmospheric Sciences Division.

Can you tell us about your field of research?

My field covers everything related to air particles and their impacts. I specifically look at the composition of these particles and the effects they have on clouds, the atmosphere and the environment in general. For instance, from the concentration of particles in the air, you can determine the amount of water they absorb and their acidity levels. The more water they hold, the more sunlight they reflect and consequently the more they help cool the atmosphere. The degree of acidity affects how much particle mass can be formed later in the day, how toxic particles can be or how much of the contained nutrients are available to fertilize ecosystems. My initial research involved writing computer codes to predict important aspects of these processes; today these codes are widely applied in air quality, weather and climate models, for example in China and Eastern Europe – regions that have major problems associated with haze and air pollution.

You also helped develop an instrument for counting these particles.

During my PhD research at Caltech, my colleague Greg Roberts and myself came up with the idea of designing a prototype instrument that could measure something that was quite challenging at the time: the concentrations of particles that eventually became cloud droplets. The instrument, called a "Cloud Condensation Nuclei Counter", was then patented and licensed to a company in Colorado, USA, and is available on the market since 2005. Today it’s used by research groups worldwide, and deployed on aircraft, ships and ground stations to generate a much needed climatology of Cloud Condensation Nuclei, which in turn allows us to make more accurate weather and climate models. We were lucky – not only did scientists really need the kind of instrument we developed, but found a company that did an amazing job in producing a commercial version that is as close to a “plug and play” instrument as it gets. For 14 years now, our group has been deploying these instruments everywhere we can. For example, by installing the instrument on an airplane, we were able to analyze particles in the Arctic air, in hurricanes and polluted airmasses in the US and Europe. The world is our real laboratory!

What about your research on ecosystems and public health?

That’s a field we branched into just a few years ago. It is now established that breathing air particles at elevated levels can be a major cause of premature death worldwide. We want to understand why this happens, and also look into the effects of air pollution on entire ecosystems, especially those of our oceans. Airborne particles containing iron, copper and phosphorus (which are ubiquitous and come from a wide range of sources) that can serve as fertilizers for oceans and provide important nutrients – but the same compounds may be toxic to humans. So we are developing instruments that measure the concentrations and toxicity of these particles and help us better comprehend their environmental impacts. We are also working on tools and methods to detect and quantify viruses, bacteria and fungi in the air and assess their consequences. These are all areas where we still have a lot to learn.

You received an ERC Consolidator Grant for your PyroTRACH project on air particles created by fires. Is that also a field that remains largely unexplored?

Climate change is creating more and more extreme events – including fires – and we still need to learn much about what the resulting particles do. We know that they stay in the air for around seven days after they are emitted, but the methods used now to detect their origin (i.e., from fires) work well only up to about two days from their emission. For this reason, the impacts of smoke particles on public health, ecosystems and climate are highly underestimated because we cannot identify them for most of their lifetime! Resent research from the group indicates that the toxicity of such “aged” smoke particles can be as much as four times higher than freshly emitted smoke. These particles could also be a factor in global warming, since they absorb sunlight and warm the planet just like greenhouse gases. PyroTRACH aims to develop ways to better detect these particles long after their emission and understand how properties changer over their lifetime and affect humans and the climate.

Why did you decide to come to EPFL?

I was attracted by the opportunity to work with people from a wide variety of fields, at the crossroads of urban development, healthcare and ecosystem research. Today most of the world’s population lives in cities and the trend towards urbanization is accelerating. This kind of joint research can therefore benefit our global society. And a school that combines architecture, civil engineering and environmental engineering is perfectly positioned to develop effective solutions and responses to these challenges. In addition, both Switzerland and the EU make considerable resources available to researchers in my field. And this region offers an excellent quality of life for my colleagues and my family. We’re really happy to be here.

You split your time between teaching and research. How do you view these two roles?

I like every aspect of my job. I enjoy problem-solving through research, and teaching is a source of constant rejuvenation. It’s very gratifying to instruct the next generation; they have incredible enthusiasm. These budding engineers will face an array of new challenges and problems to solve. Talking with students also inspires new research ideas and approaches. Even though you may think you know a subject well, when you teach it you often come across areas where your knowledge is lacking, or you begin to see things from a perspective that you never considered before. It’s both an enriching and humbling experience.