Pine Needles Predict Air Quality? USU Researcher Says Yes

Modern science has provided equipment for sampling air quality, but Mother Nature has been doing it much longer — with nothing but a bundle of pine needles.

Professor Randy Martin from the Utah Water Research Laboratory has used pine needles as passive air quality samplers in a recent study comparing urban air quality in Rose Park and Spanish Fork, Utah.

Many compounds in the air, such as pesticides, are attracted to the fats on the surface of pine needles. Martin wanted to know if those same fats would attract toxic compounds known as polycyclic aromatic hydrocarbons, or PAHs.

PAHs are a series of hydrocarbon compounds with linked benzene rings. All the hydrocarbons are joined together “kind of like a pair of bug glasses,” Martin said. And more important than their look is their effect on human health.

Martin said PAHs are mostly associated with petroleum activities, including cars and refineries, as well as burning wood, grass and coal. They are toxic, and the Environmental Protection Agency has 16 compounds on their hit list.

Martin wanted to know how those 16, plus a few others, show up in different communities.

“We know some communities are subject to worse levels of environmental contaminants, and it’s usually tied to economics and demographics,” Martin said.

To get a broad picture of his two sample Utah cities, Rose Park and Spanish Fork, Martin and his team looked to pine needles as long-term passive samplers.

“They’re always out there in the environment, so over a period of a year, they’re really good at averaging the concentrations that the neighborhoods would be exposed to,” Martin said.

They recruited students from the Salt Lake Center for Science Education and Spanish Fork Middle School to help them collect pine needles from Austrian pines, Scots pines and blue spruces.

Once they had the samples, they took them back to the lab at the UWRL to freeze, grind up, and then extract the PAHs to separate and analyze.

Mother Nature was good to her word. The pine needles were effective at attracting PAHs. Martin said each type absorbs differently, so they had to account for that in their lab tests, but they were able to get an overall map of each city’s PAH concentrations, which told them where they needed more intense sampling.

They found that Rose Park had concentrations about five times higher of these toxic compounds. They could even identify specific regions of the city with the highest concentrations near the interstate, airport and refineries.

“It’s not surprising that Rose Park concentrations were higher, but now we have evidence,” Martin said.

He also said the students were excited to see the results from their citizen science efforts.

“We say, look, here’s where it’s really highly concentrated, here’s where it’s not,” he said. “This is from your data.”

The pine needle project is part of a larger National Science Foundation grant to link metabolites in wastewater to neighborhood air quality.

“Just like you do with disease states, just like you do with COVID, with measles,” Martin said, “you can look at the wastewater and see what the local population has.”

While Martin looked for air pollutant concentrations through first pine needles and then traditional localized samplers, Jennifer Weidhaas at the University of Utah collected water samples to look for those same pollutants in local wastewater. They hope that in the future it’ll be possible to use wastewater surveys to see where people are being exposed to air pollutant compounds.

Martin expressed excitement for this new way of connecting the dots for air quality exposure.

“We’re actually now looking at the relationship between air and incorporating that into your body and into the waste stream,” he said.

He also said he wouldn’t be surprised if the pine needle method of sampling gets more attention in the future. He said it gives a great generalized picture, and it’s a pretty cool way to do science.