More plants and trees could help the US reduce air pollution by 27% according to new research

Trees and other plants can help slash pollution near factories and other sources by an average of 27%, a new study suggests.

Planting trees tends to be cheaper than implementing new technology. And, according to a new paper, they can be of great help in our efforts to curtail air pollution. The study shows that plants are a cheap but effective alternative to cleaning the air around industrial sites, roadways, powerplants, or drilling sites.

Plant a tree, get fresh air free

“The fact is that traditionally, especially as engineers, we don’t think about nature; we just focus on putting technology into everything,” said Bhavik Bakshi, lead author of the study and professor of chemical and biomolecular engineering at The Ohio State University.

“And so, one key finding is that we need to start looking at nature and learning from it and respecting it. There are win-win opportunities if we do — opportunities that are potentially cheaper and better environmentally.”

For the study, the team collected public data on air pollution and vegetation, on a county-by-county basis, for the continental 48 states. They analyzed the effect trees and other plants have on air pollution levels and then calculated the costs of adding extra plants and trees. In effect, they checked to see how able current vegetation levels are at mitigating air pollution, and then estimated the effect of increased plant presence on air pollution.

The team reports that for 75% of the counties that were included in this analysis, it was cheaper to use plants to mitigate air pollution instead of technological solutions (smokestack scrubbers for powerplants, for example). In several cases, the team explains that plants may actually be the better choice when combating pollution.

There is one area where the team found technology to be superior to plants at cleaning air pollution — industrial boilers. In the manufacturing industry, both ecosystem upgrades and technological solutions can perform the task, and both offer up cost-saving opportunities. However, because this sector is so broad and varied, it’s hard to find a one-size-fits-all solution. They should be implemented on a case-by-case basis while taking account of the particularities of each situation.

They found that adding trees or other plants could lower air pollution levels in both urban and rural areas as well, though the success rates varied depending on, among other factors, how much land was available to grow new plants and the current air quality.

“[The findings] suggest that even though vegetation cannot fully negate the impact of emissions at all times, policies encouraging ecosystems as control measures in addition to technological solutions may promote large investments in ecological restoration and provide several societal benefits.”

All in all, they estimate that restoring vegetation “to county-level average canopy cover” can reduce air pollution by an average of 27% across the investigated counties. The figure varies by county and region — for example, a county in Nevada would have a lower plant cover than a same country in Ohio, because the desert can support less vegetation. The analysis didn’t include ozone pollution because data on ozone emissions is lacking, the team explains. Furthermore, they didn’t consider whether certain species are better at cleaning air pollution, although Bakshi said it’s likely that the local species will have an effect on air quality.

“The thing that we are interested in is basically making sure that engineering contributes positively to sustainable development,” Bakshi said. “And one big reason why engineering has not done that is because engineering has kept nature outside of its system boundary.”

The paper “Nature-Based Solutions Can Compete with Technology for Mitigating Air Emissions Across the United States” has been published in the journal Environmental Science & Technology.