Community Radio of Northern California asks: “What if you could look at the plants in your garden in order to learn if the air around you is clean or dirty?” Turns out the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, enables us to do just that with their new ozone garden. There, the plants show a visible reaction when ozone reaches a certain level.
Ozone is an oxidant in our atmosphere that can be harmful to both people and plants. NASA, which also has an ozone garden for research, further explains: “One of the primary components of air quality is the amount of ozone found in the air we breathe (troposphere). While ozone in the upper atmosphere (stratosphere) protects life from harmful ultraviolet radiation, ozone in the lower atmosphere (troposphere) is a pollutant that damages plants and human lung tissue.” Surface-level ozone can reach dangerously high levels on hot, sunny days, causing create breathing problems, especially for children.
The Environmental Protection Agency (EPA) has set the limit for humans at 75 parts per billion, but Community Radio writes that it’s considering lowering that level. Some plants start showing effects at 40 parts per billion.
NCAR’s test garden has four types of plants, which have been selected for their “sensitivity to ozone.” These include “milkweed, snap bean, potato and cutleaf coneflower.” When ozone begins to take its toll, Danica Lombardozzi, a postdoctoral researcher at NCAR, told Community Radio: “You start to see damage on the leaves. A bunch of little black spots.”
These plants are “like a canary in the coal mine,” said Lombardozzi. When the plants react to the ozone, some of the chlorophyll cells in the plant’s leaves die. “The effect isn’t instant, though – the leaf blackening depends on how long the ozone is in the air and how long the plants are exposed.” Typically, the worst ozone comes in later July and August.
As NASA explains in a comprehensive report about their bioindicator ozone garden, ozone could also be very bad news for the plant world, and, in turn, us. During high periods of ozone, there have been known negative impacts: “Ozone air pollution has been known since the late 1950s to cause significant injury and economic losses to many agricultural crops, herbaceous ornamentals, and native plants.” Forests could also be affected.
Here’s a guide on how to set up an ozone garden as a monitoring station. NASA also created a toolkit that explains how educators and middle school students can create their own ozone garden as a scientific learning exercise.
If you have kids or existing breathing problems and are concerned about ozone, you can also check out OzoneMatters.