Nav: Home

Princeton scientist solves air quality puzzle: Why does ozone linger long after its ban?

April 20, 2020

When high in the atmosphere, ozone protects Earth from harmful solar radiation -- but ozone at ground level is a significant pollutant. Exposure to high concentrations of ground-level ozone aggravates respiratory illnesses, thus exacerbating the negative health effects of heat and contributing to the catastrophic impacts of recent heatwaves and drought in Europe.

In Europe, despite laws limiting pollution from cars, trucks and factories, there has been little improvement in ozone air quality. An international team led by atmospheric scientist
With hot and dry summers expected to become more frequent over the coming decades, this has significant implications for European policymakers, noted Lin, a research scholar in atmospheric and oceanic sciences and the Cooperative Institute for Modeling the Earth System at Princeton University.

In a new study published today in Nature Climate Change, Lin and her colleagues demonstrated that vegetation feedbacks during drought worsen the most severe ozone pollution episodes.

"We show that declining ozone removal by water-stressed vegetation in response to climate warming can explain the slow progress towards improving ozone air quality in Europe," she said. "Under drought stress, plants are less effective in ozone removal via stomata -- small pores in the leaves of vegetation that are responsible for controlling carbon dioxide transport for photosynthesis and water vapor losses."

Such land-biosphere feedbacks have often been overlooked in prior air quality projections. This study quantified these vegetation feedbacks using six decades of observations and new Earth system model simulations developed at the Geophysical Fluid Dynamics Laboratory, a division of the U.S. National Oceanic and Atmospheric Administration located on Princeton's Forrestal campus.

Lin and her colleagues found that severe drought stress can cause as much as 70% reductions in ozone removal by forests. "Accounting for reduced ozone removal by drought-stressed vegetation leads to a three-fold increase in high-ozone events -- above 80 parts per billion," Lin said. That is significantly worse than the European Union's ozone target: 60 parts per billion, not to be exceeded on more than 25 days per year. For reference, the U.S. standard is 70 parts per billion, not to be exceeded on more than 4 days per year.

The European Union has established an extensive body of legislation to reduce regional emissions of smog-forming chemicals from member states, but despite 45% to 70% reductions in smog-forming chemicals across a 40-year period, summertime ozone levels measured in Europe actually climbed, especially during the 1980s and '90s.

Based on their findings, Lin said, governments will need even stronger emission controls to lower ozone air pollution.

While this study focused on Europe, their findings have broad implications. Substantial reductions in ozone removal by vegetation were also observed during North America's historic heat wave and drought in summer 2012, according to an

Over the coming decades, as the climate warms, it will be increasingly important to account for vegetation feedbacks to determine the effects of extreme pollution events, she said.
Lin conducted the research with

"Vegetation feedbacks during drought exacerbate ozone air pollution extremes in Europe," by Meiyun Lin, Larry W. Horowitz, Yuanyu Xie, Fabien Paulot, Sergey Malyshev, Elena Shevliakova, Angelo Finco, Giacomo Gerosa, Dagmar Kubistin and Kim Pilegaard, appears in the April 20, 2020 issue of Nature Climate Change (DOI: 10.1038/s41558-020-0743-y). The research was supported by NOAA (NA14OAR4320106 and NA18OAR4320123) and the U.S. Department of Commerce.

Princeton University

Related Ozone Articles:

Investigating the causes of the ozone levels in the Valderejo Nature Reserve
The UPV/EHU's Atmospheric Research Group (GIA) has presented a database comprising over 60 volatile organic compounds (VOC) measured continuously over the last ten years in the Valderejo Nature Reserve (Álava, Basque Country).
FSU Research: Despite less ozone pollution, not all plants benefit
Policies and new technologies have reduced emissions of precursor gases that lead to ozone air pollution, but despite those improvements, the amount of ozone that plants are taking in has not followed the same trend, according to Florida State University researchers.
Iodine may slow ozone layer recovery
Air pollution and iodine from the ocean contribute to damage of Earth's ozone layer.
Ozone threat from climate change
We know the recent extreme heat is something that we can expect more of as a result of increasing temperatures due to climate change.
Super volcanic eruptions interrupt ozone recovery
Strong volcanic eruptions, especially when a super volcano erupts, will have a strong impact on ozone, and might interrupt the ozone recovery processes.
How severe drought influences ozone pollution
From 2011 to 2015, California experienced its worst drought on record, with a parching combination of high temperatures and low precipitation.
New threat to ozone recovery
A new MIT study, published in Nature Geoscience, identifies another threat to the ozone layer's recovery: chloroform -- a colorless, sweet-smelling compound that is primarily used in the manufacturing of products such as Teflon and various refrigerants.
Ozone hole modest despite optimum conditions for ozone depletion
The ozone hole that forms in the upper atmosphere over Antarctica each September was slightly above average size in 2018, NOAA and NASA scientists reported today.
Increased UV from ozone depletion sterilizes trees
UC Berkeley paleobotanists put dwarf, bonsai pine trees in growth chambers and subjected them to up to 13 times the UV-B radiation Earth experiences today, simulating conditions that likely existed 252 million years ago during the planet's worst mass extinction.
Ozone at lower latitudes is not recovering, despite Antarctic ozone hole healing
The ozone layer -- which protects us from harmful ultraviolet radiation -- is recovering at the poles, but unexpected decreases in part of the atmosphere may be preventing recovery at lower latitudes.
More Ozone News and Ozone Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at     You can read The Transition Integrity Project's report here.