Introducing: Eben Cross

Example of Eben’s ultra-fine particulate matter sampling while biking. The particle counter is in his backpack, air gets sucked through the inlet tip (grey piece directly over his left shoulder) and sent to the detector, which saves the data (particle concentrations, time, GPS coordinates, etc.). Photo credit: Eben Cross.

Some people – myself included – have to make an effort and learn how to address a room, how to build rapport with a diverse group of people, how to teach without sounding like a know-it-all. Others seem to possess a gift for effortless camaraderie in a variety of situations. Eben Cross is one of these latter individuals.  

Eben – a Research Scientist in Jesse Kroll‘s group at MIT – possesses a talent for making people feel at ease. He conducts research in atmospheric chemistry, a field that might seem somewhat abstract and unapproachable. Yet speaking with him about his research feels like you could just be having a casual chat down at the pub. That’s a valuable skill, one that he puts to good use when teaching middle school kids about air pollution or undergraduates how to troubleshoot in the field.

I had the great pleasure of crossing paths with Eben while I was a graduate student, and we talked recently about his path into a scientific career. Today I’m so pleased to have him explain – in his characteristically approachable style – the importance of mentors, of grabbing hold of opportunities wherever they might arise, and why you might want to hold your breath if you’re walking near a fire truck.

…ON HOW AIR IS NEVER JUST AIR.

Although you can’t see it, in every cubic centimeter of air (that’s the volume occupied by just the tip of your pinkie finger) – in your house right now, in my apartment, especially since I just fried an egg – there are tens of thousands, even hundreds of thousands of tiny particles.  The sheer number of particles that are just floating around in the air is pretty mind boggling. It’s hard to conceptualize that many particles when you can’t see them! In fact, your nose does a much better job than your eyeballs – and it is the smell of that fried egg or vehicle exhaust or wood-smoke that is the first indicator that there are particles in the air.

Eben and fellow TREX leader James Hunter at ~9000 ft, on their way up to the top of Mauna Kea, Hawaii. Photo credit: Eben Cross.

At first, most kids don’t get it. [In a classroom demonstration,] we rip a piece of paper in front of a [particulate] sensor and the number [of particles] goes from 1,000 to 500,000 as the tiny paper fibers are released into the air, sucked into the device, and counted as they cross paths with a laser beam – scattering light into a detector. And the students sit there disbelieving what the sensor is ‘seeing’ – having moments earlier guessed 10, maybe 50 particles. How can there possibly be that many particles!? If there’s that many particles here and we can’t even smell anything, what happens if we’re in a room where we smell something weird? What about the cafeteria? What about the school buses?

There’s an entry to atmospheric chemistry that comes along with grasping the sheer number of particles floating around in the air, and simple exercises like this inspire curiosity-driven questions about where all those particles come from, where they are going, and what impact they have on our daily lives.

…ON FEELING EMPOWERED BY HARD WORK AND PREPARATION.

I have had many outstanding and influential teachers in my life, but a pivotal moment [of my path into science] was taking high school chemistry with Mr Raymond (or ‘Raymond’ as I affectionately called him). You see, Raymond was ‘balls to the wall’ and a little bit crazy. His occasional (and effective) use of profanity was one teaching tactic that as a high school student I really appreciated. Not to mention that he didn’t take any bullshit from anyone and he expected you to work really hard.

Eben (in yellow) and colleagues conducting a black carbon measurement inter-comparison study at Boston College, during Eben’s PhD. Photo credit: Eben Cross.

He made it clear that, in order to understand the subject of chemistry, you had to work hard, probably harder than you’ve ever worked before. His intensity and enthusiasm were unmatched and he managed to highlight the awesome power of chemistry in a way that motivated us to work hard and really try our best to ‘get’ it. For me, Raymond transformed chemistry from a scary, intimidating subject into a fascinating and doable one.

Coming from a public school in the middle of rural Massachusetts, you feel somewhat intimidated when you match up against students from high-powered (wealthy) schools. But Raymond helped us feel powerful, always emphasizing that he was preparing us to be the best (college) chemistry students that we could possibly be, before we were even in college! His expectations instilled a tremendous amount of confidence in me and I felt empowered as a result.

So when I did go to college and I walked into that chemistry classroom with all those other kids (many of whom had come from those high-powered (wealthy) educational backgrounds), I felt like I could do it. Thanks to Raymond, I felt like I was good at it, which is a really neat and powerful feeling, especially for an otherwise easily intimidated college freshman.

…ON HOW QUANTITATIVE CHEMISTRY CAN BE A GATEWAY TO TALKING ABOUT THE ENVIRONMENT.

Eben teaching air pollution with LEGO to a classroom of 8th graders at Susan B. Anthony Middle School in Revere, MA. Photo credit: Eben Cross.

I really liked the fact that you could quantify things in chemistry; in many ways it felt tangible. I think the combination of physics and chemistry is particularly powerful when speaking about the environment and our (human-kind’s) influence on it.

[Atmospheric chemistry was] where I discovered how I could use my passion for chemistry to tackle environmental issues. I think atmospheric chemistry allows you to make inroads with people who don’t necessarily think or align themselves with environmentalists. Through the chemistry of the atmosphere, you can have a tangible, concrete, and powerful conversation and help folks realize that the projects that you’re working on overlap with things that they actually care about.

You can use chemistry in a quantifiable way that says: if you or your kids are exposed to this chemical, it’s really harmful. And it’s not about increasing taxes or big political issues; it’s about what’s best for your overall health and the health of the people you care about. I think chemistry has a way of getting through all the muck of the politics and getting right at issues that have some traction with a broader swath of the community.

…ON WHY YOU MIGHT WANT TO HOLD YOUR BREATH WHILE WALKING DOWN THE STREET.       

One of my recent projects has been biking with a particle sensor. You see, I have this sensor that can detect (and count) all of the ultrafine particles – the really tiny ones – in the air. We care about these ultra-fine particles because they are so small that they are efficiently transported through your nose and deposited deep within your lungs. I’ve been biking to and from work for almost a year now with my particle sensor counting all the particles I encounter along the way. I’ve also got a little GPS that tracks my position, so I can map the ultrafine particle pollution concentrations in real-time.

Eben sampling the emissions from cook stoves in the D-Lab at MIT. Photo credit: Eben Cross.

Ultimately, we want to be able to understand, on a second-by-second basis, how many particles you get exposed to during your daily routine.  As you can imagine, there are remarkable changes in your personal air quality throughout the day.  For example, if a fire truck happens to drive by me while I am biking to/from work, the number concentration of ultra-fine particles goes from 10,000 particles per cubic centimeter of air to as many as 12,000,000 particles per cubic centimeter of air! That’s crazy!

Mapping individual exposure to ultra-fine particles is an aspect of air quality/pollution monitoring that has largely been left unmeasured until recently. There are tremendous research opportunities to pursue micro-environment air quality issues and help fill in this knowledge gap, and this is one reason why atmospheric chemistry is so exciting.

…ON TEACHING THROUGH PLAY.

There are a lot of aspects of chemistry that are completely invisible [to the naked eye] and very hard to conceptualize. As Melissa [Garren] said, making the unseen seen, or the invisible visible – that theme is also at the heart of everything I do with respect to air pollution.

Using LEGO^© is one way that I try and make the invisible visible: With colleagues in the MIT Edgerton Center, I’ve developed a teaching tool for middle school students that uses LEGO to teach and model complete and incomplete combustion.

[Side note: you can read more about the Understanding Air Lego teaching tool here.]

This effort feeds back to the idea of confidence building – for a sixth grader who’s never talked about chemistry before, it can be a pretty intimidating subject.  But these very same 6^th graders are super confident with LEGO. In fact, for many of them, they feel like they’re more competent with LEGO than I am (which at this stage of my career, is probably true). When I ask them to build a certain molecule, they’re off and running.

View of the sampling tower (60′) at the SOAS field site in Brent, Alabama, where Eben spent several weeks this summer. High volume filter samplers in the foreground. One of the smaller research aircraft is flying over the tower during this particular shot. They do this routinely to compare the pollution measured at the tower with air aloft. Photo credit: Eben Cross.

So without even necessarily having seen the periodic table before, they have suddenly built a molecule out of LEGO, they can determine its formula based on which color blocks they used, they can learn the molecule’s name, and discover that their molecule has real-world implications with concrete and tangible effects on their everyday life. They start to feel more and more confident unraveling the complexities of the atmosphere (and chemistry in general) one LEGO brick at a time.

…ON THE HUGE PUBLIC HEALTH IMPLICATIONS OF AIR POLLUTION, AND WHY SMALL THINGS MATTER.

Major air quality issues are often driven by primary emissions from combustion sources close to populations.

For example, there was an MIT study released recently [about air quality issues in China]. The ambient background concentrations of particles in regions of China are in hundreds of micrograms of particulate per cubic meter. The MIT study showed that each increase of 100 micrograms per cubic meter lowers life expectancy at birth by 3 years. So if you’re in born in an environment that has 150 micrograms per cubic meter rather than 50 micrograms per cubic meter, you’re going to die 3 years earlier.

That has huge public health and economic consequences. Exactly why that’s the case isn’t understood very well. So I think a key question becomes when we really dig in and understand the chemistry of these particles, what is it about the particles that causes them to be so deleterious to our health?

It could be a very small part of the chemistry of that particle. It could just be a trace species that happens to be there, rather than the bulk of the mass of the particle. But if you breathe in a very small particle that gets deep into your lungs and transferred into your bloodstream, it is probably not going to be healthy for you.

The TREX 2013 crew, Hawaii, with an airborne Eben. Photo credit: Eben Cross.

It’s such a heterogeneous environment – if I’m standing on the road and a FedEx truck drives by, I get pummeled with particles, but if you’re standing 100 meters away from the sidewalk you don’t get any of them. So people’s proximity to pollution becomes a key factor and I don’t think anyone has a strong handle on the exposure of humans in transient environments on timescales that are actually very short.

…ON TAKING ADVANTAGE OF OPPORTUNITIES WHEREVER THEY ARISE.

Spring semester of my senior year in college, I took a class called Instrumental Methods and Analysis with Professor David Lewis.  Professor Lewis was also a part-time Principal Scientist at Aerodyne Research, a small company located in Billerica, MA, that focused on air pollution research. As part of the lab component for the class, one of our options was to wake up at 5 AM on a couple Tuesdays that semester and drive the 2 hours from Connecticut College to Aerodyne.

I was captivated by Professor Lewis’ initial description of what they did at Aerodyne: ‘They shoot lasers across roadways, measure the absorption signal in the light beam and quantify the gas-phase emissions from passing vehicles.’ As an undergrad who wanted to solve environmental problems through the power of chemistry, I felt like I had hit the jackpot! So I happily woke up early and drove to Billerica with Dave a few times that semester.

I didn’t get into graduate school directly following my time at Connecticut College and this turned out to be a blessing. When Professor Lewis learned that my situation [after college] wasn’t really clear, he offered me a 10-week internship to work at Aerodyne over the summer. So literally the day after I graduated, I moved to Lexington, MA, and started working with Aerodyne. I’ve been working closely with my Aerodyne colleagues ever since.

Eben showing MIT undergraduate students Phoebe and Alex how to set up a few of the sampling instruments in the back of their make-shift mobile air quality sampling lab (a rented mini-van), as part of the TREX project. Photo credit: Eben Cross.

That felt a bit serendipitous – to be in that class at that time and for Dave to see my potential and offer me the opportunity to jump head-first into the world of atmospheric chemistry research.

…ON THE UNFORESEEN BLESSINGS OF A CAREER IN SCIENCE.

I’ve had the privilege of participating in many field experiments in different parts of the world, from the coast of Nova Scotia, to the forests of Alabama, to the heart of Mexico City. Field research has taught me to never take anything for granted and that if my instruments breaks – I have to do whatever it takes to get it back up and running. The intensity and MacGyver-mentality of field work is both exhausting and rewarding and creates an exceptionally strong camaraderie amongst your fellow scientists. Working alongside such passionate, smart, and enthusiastic people is another reason why atmospheric chemistry is awesome.

Leading the TREX (Traveling Research Environmental eXperiences) course on the Island of Hawaii for the last 2 years has also been extremely rewarding. Since few of the undergraduates have done field research before TREX, this experience has allowed me to introduce the students to the intensity and MacGyver-aspects of field work and share my enthusiasm for atmospheric chemistry with them.  In many ways, TREX has allowed me to feel most like Mr Raymond, encouraging the students to work hard, push their limits, and have fun in the process.

[Side note: here is an article written about the TREX student’s work on West Hawaii Today.]

…ON THE IMPORTANCE OF HAVING GOOD MENTORS.

It’s all comes back to that empowerment [having mentors who encourage you]. I can’t say enough about the confidence factor and having Raymond say over and over again, as we’re struggling through a lab experiment,

Eben’s wedding vows. Yes, he actually delivered his vows in the form of a graph… and he is still happily married. Photo credit: Eben Cross.

“When you get to college and you walk into chemistry class, you’re going to kick these titrations in the ass because you will have done a hundred of them already! It’s not going to be a big deal and you’re going to power on through. All this hard work hard is going to pay off.  Trust me.”

He was adamant about wanting us to succeed beyond the walls of Ralph C. Mahar Regional High School.

My scientific journey is a product of many outstanding mentors.  My continued development as a scientist reflects their collective wisdom, support, encouragement, and enthusiasm. I am extraordinarily lucky.