It’s a time machine. It’s a tanning booth. It’s … a mobile smog chamber

The blue ultraviolet glow that often bathes the Powerhouse Energy Campus’ first floor isn’t a time machine, nor a tanning booth, as curious onlookers have guessed.

It’s an experimental smog chamber, and it’s going to help CSU scientists decipher just what harmful particles may lurk in the air we breathe.

engineering students
Master’s student Abril Galang (foreground) and undergraduate researcher Liam Lewane perform calibration testing on the smog chamber, of which Lewane led construction and design.

The smog chamber is a project led by air quality researcher Shantanu Jathar, assistant professor in the Department of Mechanical Engineering and a member of the CSU Energy Institute. Devices that simulate atmospheric processes in controlled settings, smog chambers were first employed to study Los Angeles’ famous haze in the mid-20th century. Today, atmospheric chemists use them to analyze photochemistry of individual compounds.

But Jathar is an engineer, so he’s more interested in a messier mixed bag of actual pollutants, rather than the well-defined lines of this or that model compound. That’s why his smog chamber, unlike standard ones, is mobile – designed to be packed on a truck and transported to pollution sources in the field.

Liam Lewane, a third-year undergraduate researcher working with Jathar, has led the construction of the nearly complete chamber. It features a modular design, ultraviolent lights that mimic important wavelengths in the solar spectrum, and a self-cleaning flushing system for rapid back-to-back experiments.

Downstream of the tailpipe

The smog chamber is just one tool Jathar is deploying for his overarching research aim: to better understand emissions and the atmospheric processing of pollutants from a range of energy sources, be they gasoline, diesel or natural gas engines, or biomass cookstoves. His focus isn’t on primary emissions of organic pollutants, but rather, what happens to those emissions “downstream of the tailpipe” – how they change and disperse in the atmosphere. This moving target of pollutants paints a trickier picture; anything from wind speed to temperature to sunlight can affect their fates.

Most environmental regulations focus on direct emissions – the stuff spewing from the smokestack or tailpipe. Car emissions tests, for instance, measure concentrations of gaseous compounds like oxides of nitrogen that are byproducts of combustion.

“The question is whether tailpipe regulations are actually effective in reducing impacts on the environment, and on our health,” Jathar said.

The formation of secondary organic particulate matter accounts for a large portion of atmospheric pollutants, but they aren’t as well understood as their more easily tracked primary counterparts. New technologies like three-way catalysts, diesel particulate filters or selective catalytic reduction systems, all aimed at emissions reduction, trigger questions about whether these systems are altering the chemical properties of the emissions, and possibly making them more harmful.

From wildfires to biodiesel

Jathar leads or co-leads several studies on such pollutants downstream of the tailpipe. Most recently, he received a Ralph E. Powe Junior Faculty Enhancement Award from the Oak Ridge Associated Universities (ORAU) to study fine-particle pollutants from combustion of biofuels.  Biofuels are increasingly used as substitutes for traditional fuels.

For the ORAU proposal, he’s analyzing differences in particle pollution between conventional diesel and biodiesel combustion. He will investigate how much particulate pollution is reduced by burning biodiesel, what happens to those particles when they are dispersed in the atmosphere and how that alters their toxicity. Department of Chemistry Professor Chuck Henry is helping Jathar develop a method for quantifying those toxicity levels.

The chemical composition of diesel and biodiesel are completely different. But their post-combustion emissions are oddly similar. Why is that? One hypothesis is that most of the emissions are actually coming from the lubricating oil, not the fuel. Jathar and Henry aim to find out.

Beyond the ORAU work, Jathar is involved in several other studies relating to secondary particulate matter. He’s working with Jeff Pierce in the Department of Atmospheric Science to look at the chemical evolution of wildfire smoke particles. He also has an ongoing project with Delphine Farmer in Chemistry about the production of isocynanic acid, a highly toxic gas, from diesel engines.

As for the smog chamber, Jathar and Lewane are currently performing calibration and validation testing before bringing it into the field. One of their first projects will be in collaboration with the Fire Sciences Laboratory in Missoula, Mont. In an effort supported by the National Oceanic and Atmospheric Administration, they’ll use the smog chamber to study smoke particles from wildfires.