Looking at smog from both sides now: Jathar lab receives grants to study urban air pollutants

A mechanical engineering professor at Colorado State University struck federal funding gold, not once, but twice this year.

Shantanu Jathar
Shantanu Jathar, Energy Institute researcher and associate professor of mechanical engineering.

New grants from the NSF and NOAA to CSU’s Shantanu Jathar promise to advance our understanding of how air pollution is affected by volatile chemical products, or VCPs — things like personal care products, cleaning products, paints, solvents, inks, pesticides, and other consumer and industrial chemicals.

“Both of these grants are thinking about volatile chemical products as an emerging source of air pollution,” Jathar said. “To give you one example, there’s a chemical compound called limonene. Limonene is what you smell when you squeeze an orange peel. It’s in everything — your dishwasher soap, your hand soap, things like that. And once it’s in the atmosphere, limonene and similar compounds can react and form these fine particles, and on very, very hot days, it can account for a quarter of the man-made ozone pollution in large metropolitan areas. And the question is, do we need limonene for the product to do its cleaning job?”

The two awards approach the problem of VCP pollution from very different angles:
• NSF supports a detailed study of VCP pollution chemistry in controlled laboratory conditions
• NOAA supports contributions to the broad AEROMMA field campaign, which combines airborne and ground-level air quality sampling with satellite observations to create the most complete picture yet of the real-world behavior of VCPs in the environment.

An emerging focus at CSU

As VCPs gain attention as an important public health issue, CSU researchers are eager to advance the basic scientific understanding of these factors. Jeff Pierce, professor of Atmospheric Science at CSU and a co-principal investigator on the NOAA grant, said, “We are excited to work to understand the chemistry that governs the pollution from these less-considered sources.”

The work adds to a growing body of research on air quality, aerosol behaviors and air pollution happening at CSU, said Delphine Farmer, professor of chemistry at CSU and a co-principal investigator on the NSF grant.

“As so little is known about VCP chemistry, we really needed a diverse team of researchers with different measurement and modeling capabilities to capture the many facets of these molecules,” Farmer said. “This project is part of a general thrust of multiple research projects here, so I think CSU is well positioned to be a leader in the topic.”

Jathar, too, sees CSU as an emerging leader in the field with chemists, epidemiologists, climate scientists, air pollution scientists, and mechanical and civil engineers all working together on the problem.

“Some of our success in winning some of these competitive proposals is because we have this collaborative cohort that brings together expertise that a single person just cannot have,” he said.

Massive collaboration, different models

Still, the work wouldn’t be possible without bringing in expert collaborators at institutions across the United States.

VCPs pose a dauntingly complex problem, both because of how many different chemical compounds are involved and because of how little is known about their interactions with each other and with environmental factors once they’re released into the atmosphere. This complexity is reflected in the massively collaborative nature of the grants.

“The two grants that we have actually have very different models for collaborative work,” Jathar said. “The NSF project is what’s called a ‘collaborative proposal,’ with CSU serving as the lead of four institutions. We have a total of four co-PIs, the total grant is slightly more than $850k, and we have an additional seven collaborators, so this is a pretty big effort. The reason for that is that we are calling on expertise in very different areas.”

The NOAA grant, part of its Atmospheric Chemistry, Carbon Cycle, and Climate (AC4) program, seeks input from roughly a dozen teams to support a broader, ongoing inquiry into urban air quality.

“The Chemical Sciences Laboratory at NOAA is doing a field campaign where they have this fantastic suite of instrumentation on this state-of-the-art aircraft that they’re going to use to measure the chemical composition of the air pollutants in these five big cities,” Jathar said. “And they’ve said OK, how can you support this aircraft campaign by doing ground measurements or adding novel instruments to the aircraft, or modeling the data to develop much more insight into the problem?”

Brian McDonald, an atmospheric scientist at NOAA’s Chemical Sciences Laboratory, describes the campaign’s thrust: “These collected ground-to-air-to-satellite observations help us to get a more complete picture of particulate formation. This work has a chance to help lead to advancements in the chemistry we use in NOAA air quality forecast models. One of the gaps right now is our understanding of sources of VOCs that react with sunlight and NOX and contribute to particle formation. We’re looking forward to the results of Shantanu’s project helping us understand the formation of fine particles in and downwind of cities.”

For Jathar, the research – and the support he’s receiving from two federal agencies – is an important first step toward mitigating public health impacts.

“If you think about traffic pollution, the people who live close to highways experience a larger fraction of the burden from traffic emissions. But when it comes to consumer products, we all use them, near highways or not. We don’t know who uses more chemical products, or who is affected, and one of the reasons we don’t know is because we don’t have good models that represent the emissions of these chemical products, or how they react in urban atmospheres to cause air pollution. That understanding would be an important precursor to understanding who it affects, and how much, and what we can do about it.”