A team of researchers from the University of Pittsburgh and the Electric Power Institute have developed a method of “fingerprinting” air pollution. The developers collected samples of air emissions from several coal-powered power plant stacks in the nation and discovered a way to detect a unique signature, or fingerprint, in nitrogen oxide (NOx) compounds emitted from the stacks.

The institute is a nonprofit that is funded by the electric power industry.

J. David Felix, a doctoral candidate at the University of Pittsburgh, explains that that nitrogen has two different stable isotopes, and depending on the pollution’s source, there are different ratios of stable isotopes. The composition of NOx emissions coming from the stacks of coal-powered power plants is unique. He says their research is motivated by the results of nitrogen emissions including ozone formation and acid rain.

“Power plants have been using new technologies to reduce these NOx emissions,” Felix said. “We wanted to look at whether we could use these isotope fingerprints to study how the technology has reduced these NOx emissions from power plants.”

The researchers believe that fingerprinting NOx emissions will be significant in identifying the source of air pollution, and tracking where it ends up. Scientists can therefore determine how much of the NOx in precipitation is from coal-powered power plants.

Scientists plan on looking at rain samples to determine how far the NOx travels across the nation and how much actually comes from power plant stacks instead of other sources like vehicles or lighting. Felix says that the findings will have particular significance in the Pittsburgh region.

“For us in the Ohio River Valley, we have a lot more coal-powered power plants,” Felix said, “so this fingerprint that we’ve seen in the study is probably going to be more relevant in our area.”