Christopher X J. Jensen
Associate Professor, Pratt Institute

Steven Chillrud Visit to Pratt Institute

Posted 17 Sep 2010 / 0
Steve Chillrud with his Pratt host, Associate Professor Damon Chaky of the Department of Mathematics & Science

Every year, Pratt Institute’s School of Liberal Arts and Sciences hosts a “scholar-in-residence” who spends a few days on campus giving talks and workshops to faculty and students. The honor of selecting a scholar-in-residence rotates between the three major departments of our school: Humanities and Media Studies, Social Science and Cultural Studies, and Mathematics and Science. Last year was our year, and we selected as our scholar-in-residence Dr. Steven Chillrud of the Lamont-Doherty Earth Observatory at Columbia University. Planned for last spring, Steve’s visit had to be postponed when he got stuck in Europe thanks to the eruption of the Eyjafjallajökull volcano in Iceland. On September 16th and 17th, we hosted Steve’s “make-up visit” with a series of three events: two lectures and a hands-on workshop.

It is a bit ironic that Steve’s original visit to us would be waylaid by a natural disaster throwing up small particles into the air, because small particles are a big part of what he studies. An environmental geochemist by training, Steve has moved from looking at the historical distribution of small particles in sediment cores to considering how to best measure the effect of exposure to small particles on human health. Most recently he has been a participant in a massive study undertaken to unravel how environmental toxins and genetic variation interact to produce different health outcomes.

Most air quality monitoring is done in a relatively cheap and extremely easy manner: rooftop air monitors have been gathering data in cities for decades. But as Steve is fond of pointing out, we do not live on rooftops, and our individual exposure to toxins in the air can be highly-influenced by a number of very local factors. In terms of the air we breath, each person lives in a microenvironment, and this microenvironment can vary greatly over small intervals of time and space. Our movement even creates an invisible “personal cloud” of aerosolized particles, a phenomenon sometimes referred to as the “pig-pen effect” after the Charles Schultz character famous for being constantly followed by a very visible dust cloud.

What Steve and his collaborators have been working on is finding a way to measure the air quality experienced by individuals over the course of days or weeks. Moving away from fixed, centrally-located air quality monitors, they have pioneered the use of “personal monitors” which can measure the air quality only a few inches away from the user’s mouth and nose. What they have found is that conventional outdoor and indoor air-quality monitors fail to record the locally-high levels of air contaminants that many people experience on a daily basis.

Originally, Steve’s research group created personal monitors that were rather big and bulky, requiring that study participants wear a backpack that housed the monitoring apparatus. As many of the participants in their studies are kids (amongst whom asthma rates are high, making them a prime study group), such a large and unwieldy device created a lot of obstacles to getting comprehensive data. The final blow to the bulky backpacks came after the London bombings of July 7th, 2005: police informed Steve that his backpacks looked exactly like the devices used by terrorists in England, and would likely cause false alarms if worn on subways and buses in New York City.

The internals on the older portable air monitors, which needed to be housed in a backpack

Pushed by the need for a more practical monitor, Steve’s group began working on a series of tiny air monitors that could be carried in a pocket rather than a backpack. After building a few working prototypes, they approached the leading manufacturer of stationary air monitors (Magee Scientific) with the idea of making a personal air monitor. Rather rapidly Magee actually brought their own version to market, and Steve now uses these monitors in his research. When combined with GPS units, the air monitors have the potential to provide very accurate data on local pollutant levels.

Steve demonstrates the features of their portable air monitor
The internals on the portable air monitor created by Steve and collaborators at the Lamont-Doherty Earth Observatory
The Magee portable air monitor (in blue) and a couple of the GPS units used for personal air quality monitoring

The pollutant that Steve focuses on most closely is black carbon, the soot that comes from incomplete combustion. Black carbon has been implicated as a contributor to a number of health problems, and is a common air pollutant in urban areas. In New York City, truck traffic and diesel-burning building furnaces are the major sources of black carbon. During one of his talks, Steve outlined the results of a comprehensive air-quality study published as part of a 2009 PLANYC report on the New York City Community Air Survey. Combined with his local measurements, this large-scale data set is beginning to paint a picture of how air pollution is distributed throughout New York City.

One of the most fun parts of Steve’s visit was a workshop that allowed participants to don a vest containing the Magee personal air quality monitors and test out the air in the Pratt area. It is a long-term goal of mine to conduct some sort of research that requires me to ride my bike all day, so I jumped at the chance to ride my bike over to the nearby Brooklyn-Queens Expressway (BQE) and see how the air quality varied in a big loop leaving from and returning to the Pratt area.

Steve outfits me with a portable air monitor and GPS unit as I get mentally prepared for my run past the BQE
Me before I did my monitoring run to the BQE: notice the air intake port on my vest

To try to get a variety of different microenvironments, I rode down Classon Avenue and made a left onto Park Avenue, which put me alongside the BQE for over fifteen blocks. Making a left onto Flatbush Avenue, I rode alongside bumper-to-bumper traffic coming off the Manhattan Bridge before ducking onto Willoughby Street, riding through Fort Greene Park, and onto to Willoughby Avenue back to Pratt.

A local source of black carbon: a bus idling on Willoughby Avenue near Pratt Institute
A UPS truck idles under the Brooklyn-Queens Expressway during my monitoring ride

When integrated for intervals of one minute, my air monitor definitely showed some pretty big spikes in black carbon exposure. The first spike occurred alongside the BQE, but the really large spike seemed to occur when I was riding briefly on Flatbush Avenue, highlighting the danger posed by idling vehicles stuck in traffic. The air I was exposed to in the immediate area of Pratt was much lower in black carbon content than these high-trafficked areas just a few blocks away, which certainly supports Steve’s claim that microenvironments can vary drastically.

The equipment needed to download the data from portable personal air monitoring units

The Department of Mathematics and Science was honored to have Steve Chillrud as our scholar in residence, and we are grateful to him for his generosity throughout his visit.

Data Limitation, Department of Mathematics & Science, Environmental Justice, Experiments (General), Pollution, Pratt Institute, Public Policy, Urban Ecology

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