CU-Boulder and NCAR ozone gardens reveal harmful effects of pollution

Published: July 23, 2014

Everyone has heard about the harmful effects of pollution on human and plant health, but until recently, visualizing such effects took some imagination.

Now, new “ozone gardens” at the University of Colorado Boulder’s Museum of Natural History and the National Center for Atmospheric Research (NCAR) Mesa Laboratory make the evidence startlingly clear. Visits to the gardens are free and open to the public.

Scientists at CU-Boulder and NCAR are growing plants that develop brown and black spots on their leaves when exposed to harmful air pollution.

“Many air pollutants are not visible to the naked eye,” said Kateryna Lapina, a post-doctoral researcher in the Department of Mechanical Engineering at CU-Boulder who founded the gardens along with post-doctoral scientist Danica Lombardozzi of NCAR. “We planted these gardens to shed light on air pollution in Boulder by making its impacts easily observable by anyone. The leaf injury developed by these plants by the end of the summer will tell us how unhealthy the air we breathe in Boulder can be and how ozone affects living systems.”

The ozone gardens feature particular varietals of milkweed, snap bean, potato and coneflower, which are natural bioindicators capable of detecting the presence and frequency of high ozone concentrations. As pollution levels increase so, too, does the severity of damage exhibited on the plants’ leaves.

Pollution occurs when ozone concentration levels, formed by hydrocarbons, carbon monoxide and nitrogen oxides, increase due to emissions from vehicle exhaust and industrial and agricultural activities.

“Ozone concentrations peak in summer, when sunlight is more abundant and intense and stagnant meteorological conditions characterized by clear skies and high temperatures make pollution worse,” Lapina said, noting that ground-level ozone in the Denver metro area and Front Range region has exceeded U.S. Environmental Protection Agency (EPA) standards since 2007. 

While EPA standards call for ground-level ozone in the Denver-Boulder area to stay below 75 parts per billion on average over an eight-hour period, the Colorado Department of Public Health and Environment has recorded measurements as high as 83 parts per billion in some areas.

These harmful levels can result in breathing problems -- particularly in children and elderly residents. They also can threaten food supplies as crops become damaged and their yields are reduced.

With ozone damage recently detected on plants in Rocky Mountain National Park, the National Park Service was one of several agencies that generously provided plants for the ozone gardens.

“Despite our region’s reputation for protecting the environment, the Front Range faces an ozone pollution problem that has serious harmful effects on people and plants,” said Lapina. “We think it’s really important to educate the public about this issue.”

Students at the CU-Boulder garden and monitoring equipment at the NCAR garden will take ozone measurements on several occasions throughout the summer. Plans are in development for interactive educational activities at the gardens including public workshops for students and teachers.

Beyond education, the researchers hope the gardens will encourage changes in behavior to reduce emissions from vehicles, gasoline vapors and chemical solvents, which lead to ozone production.

“By seeing the damage that ozone causes on plants, we hope the gardens raise awareness about the harmful effects of ozone on both people and plants,” said Lombardozzi. “If enough people make small changes, like using electric rather than gasoline-powered lawnmowers, it might make a big difference to the quality of the air we breathe every day.”

Lapina and Lombardozzi got the idea for the gardens from researchers in St. Louis who are sharing their experiences with ozone gardens as part of NASA’s Air Quality Applied Sciences Team. Separately, the NASA team funds Lapina’s work with mechanical engineering professors Daven Henze and Jana Milford to model ozone-induced biomass and crop losses.

For more information about the gardens and other research being conducted by Lapina, Henze and Milford visit

Kateryna Lapina, 970-231-1717
Danica Lombardozzi, NCAR, 303-497-1777
Daven Henze, Mechanical Engineering, 303-492-8716
Courtney Staufer, CU Engineering Communications, 303-492-7190

Snap bean leaves showing moderate ozone damage. (Photo courtesy Saint Louis Science Center and Saint Louis University)