National Ozone Bioindicator Garden Network Workshop: a Great Learning Experience for ARMN’s Own Ozone Garden

By Todd Minners

I was able to attend a national workshop in August as ARMN’s representative in the Ozone Bioindicator Garden Network. Our own garden was established in 2020 at the Walter Reed Community Center and has been tracked each year since the 2021 growing season. [For more information about the garden, see “ARMN’s Ozone Bioindicator Garden: Year Six.” ]

Did you know kudzu contributes to ground ozone? Neither did I until I attended the 2026 National Ozone bioindicator garden network workshop in Boulder, Colorado. Yes, especially when stressed by heat and/or drought, Pueraria montana produces a ground ozone precursor called isoprene which along with other volatile organic compounds (VOCs) and/or nitric oxide and nitrogen dioxide (NOx) and sunlight produce ground ozone. Why should we care? Because extended exposure to ground ozone concentrations above 70 ppb (parts per billion) can cause respiratory distress in animals and humans and disrupt some plants’ ability to photosynthesize. (EPA’s U.S. National Ambient Air Quality Standard sets the public safety threshold at 70 ppb averaged over 8 hours.)

Origins of the National Ozone Garden Network

The National Ozone Garden Network traces its origins to 2012 when climate scientists at the National Center for Atmospheric Research (NCAR) created physical, public bioindicator gardens in Colorado as a hands-on way to help the public visualize otherwise invisible ground-level air pollution. Inspired by an earlier NASA-funded project in St. Louis, they planted sensitive “bioindicator” species (like cutleaf coneflower, milkweed, snap beans, and potatoes) that develop visible brown spots—known as stippling—when exposed to high ozone levels. NCAR Scientists worked with informal educators, citizen scientists, and regional sites to replicate the garden model across the U.S. and internationally. Managing organizations including the University Corporation for Atmospheric Research (UCAR), the Center for Astrophysics/Harvard-Smithsonian, and the NASA Langley Research Center secured funding through the NASA TEAM II initiative to expand the grassroots effort into a formal nationwide network. Today, the network links community science sites across the U.S., using standard bioindicator plants to gather data on ozone damage while engaging the public in air quality research. Hands-on manual ozone damage data collected at these gardens combined with airborne, satellite-based and ground sensor networks now provide a more complete look at ground level ozone concentrations, movements, and distributions. The plant leaf observations specifically tell us when ozone damage occurs, the differing severity across plant species, damage across locations year-to-year, and how damage is related to ozone concentrations measured by instruments.

The 2026 Workshop Attendees, and What We Learned

The 2026 workshop brought together representatives from 25 NASA grant-funded gardens at locations as diverse as national parks, city museums, juvenile justice centers, hospitals, nature centers, and university campuses all over the country. These included: the Walter Anderson Museum of Art in Ocean Springs, MS; Valparaiso University in Valparaiso, IN; The Nueva school in San Mateo, CA; Spelman College in Atlanta, GA; Colorado State University in Ft Collins, CO;  Gathering Ground on Washington Island, WI;  South Carolina Department of Juvenile Justice Coastal Evaluation and Development Center in Ridgeville, SC; South Dakota Discovery Center in Pierre, SD; Stony Brook Hospital in Stony Brook, NY; Snug Harbor in Staten Island, NY; Timpanogos Cave National Monument and Natural History Museum of Salt Lake City, UT; Hoyt Arboretum in Portland, OR; Marymout University and Walter Reed Recreation Center in Arlington, VA; McWane Science Center in Birmingham, AL; Fernbank Science Center in Atlanta, GA; Denali Education Center in Denali Park, AK; Durham Public Library in Durham, NH; Avon Lake Public Library in Avon Lake, OH; Reeves Meadow Visitor Center in Sloatsburg, NY; and Framingham State University in Framingham, NH. We met for three days in August at the NCAR I.M. Pei-designed Mesa Laboratory campus. It was the second of two planned workshops.  

The workshop included multiple breakout and focused small group discussions, data collection practice outside in the local bioindicator garden, and continuous opportunities to exchange insights and ideas. It helped garden team representatives develop “elevator pitches” about the program, garden vision statements, and outreach plans—including writing ourselves a postcard to be mailed in a month reminding us of all the things we “promised” to do. 😊 

One of the most interesting days featured 6-minute presentations by each garden representative. We heard complaints such as, “Why do your plants look so ragged?” (Response: “that’s how native plants look, and the other plants are past their prime growing season”); and: “Can’t you just use a sensor?” (Response: “the plants physically show ozone damage which makes it more ‘real’ and ‘tangible’ as opposed to sensor data”); as well as: “Why aren’t you growing native plants?” (Response: “because USDA selected plants for which there are known ozone-tolerant varieties that we can compare to the ozone-sensitive varieties”). We also learned how to share this information with juvenile detention kids, as well as the challenges of growing potatoes or tobacco. One of the bioindicator gardens in the program is surrounded by huge commercial wheat and soybean farms where visitors are mostly farmers and their families, another is just two planters in front of a big city science museum, and others are on rooftops, trailheads, hospital grounds, and high school or college campuses. So, despite the science focus of the gardens, we were reminded that these are all just plants growing in all sorts of environments and managed by largely amateur gardeners. Garden managers’ experiences ranged from “barely can keep plants alive,” to “harvestable crops,” and “can’t get any data when the deer eat all the plants,” to hourly sensor data being shared via a custom data link on a public library website.

The workshop featured several expert panels of NASA or UCAR scientists, data managers, and modelers, along with USDA presentations on how ozone bio-monitors help with food security. Here the focus is on tobacco, clover, snap bean, wheat, and soybean, as well as ongoing testing of ozone sensitivity with redbud (Cercis canadensis) trees. USDA provided the sobering estimate that in 2030, global soybean yields may be reduced by 16% due largely to ozone damage to crop plants. NASA engineers provided a detailed overview of their new (launched 2023) geostationary tropospheric emissions monitoring of pollution (TEMPO) instrument, which for the first time, continuously measures daytime air pollution over North America.

There was quite a bit of discussion about types and brands of ground ozone sensors, their placement, calibration, and data format, as well as data collection protocols and how to manage and integrate the manually-collected data with ground sensor-produced—and soon—satellite-produced ground ozone concentration data.

We were reminded that tropospheric ozone (less than 10km altitude) is formed by the reaction of volatile organic compounds (VOCs) with nitrogen oxides (NOx) and is thus worst during hot daytime periods. The worst recent ozone concentration in Arlington (greater than 100ppb for a few hours) was during the August Canadian wildfires.

Of course, like any good workshop we came away with homework!  Among the most significant: Share advice with our local residents on daily actions we all can consider to reduce the possibility of elevated ground ozone levels. In Northern Virginia, where vehicular exhaust and regional transit density are significant drivers of ozone, everyday actions should focus on reducing fuel emissions, minimizing chemical evaporation, and shifting the timing of daily routines.

How Can These Goals Be Accomplished?

Transportation and Commuting: 
•  Shift to public transit or micro-mobility, like taking Metro, buses, or riding an E-bike or pedal bicycle for daily commutes instead of driving solo. Trips under three miles account for a large portion of urban and suburban drive trips. Because internal combustion engines and catalytic converters take several minutes to reach optimal operating temperature, these “cold-start” short drives produce disproportionately high rates of both unburned fuel evaporation and exhaust emissions per mile.

•  Avoid unnecessary idling: Turn off the engine while waiting during school pickups, park-and-waits, or curbside drop-offs.

•  Consolidate driving trips: Group household errands into a single trip rather than taking multiple short, cold-engine drives throughout the day.

Vehicle Maintenance and Refueling:
•  Pump gas after sunset. Refueling vehicles after dark prevents gasoline vapors—a major source of VOCs—from reacting with intense midday sun.

•  Stop at the “click” to avoid topping off the gas tank and prevent fuel spillage and vapor escape.

•  Maintain correct tire pressure: Keeping tires properly inflated improves fuel efficiency, directly lowering exhaust emissions.

Around the Home and Yard:
•  Transition to electric yard tools: Replace gas-powered lawnmowers, leaf blowers, and trimmers, with battery-powered alternatives. Gas yard equipment emits a disproportionately high level of unburned hydrocarbons both during operation and via daytime fuel evaporation from vented fuel tanks and carburetors while stored. Transitioning to battery-electric or manual tools eliminates fuel-related VOC evaporation entirely, along with direct exhaust emissions. Battery life is increasing with these tools as well, and they are significantly quieter than gas-powered ones. Also, mow lawns late in the afternoon or evening. If using gas equipment, mowing during cooler hours reduces the immediate photochemical reaction of emissions.

•  Refuel and use solvents during cooler evening hours. Refueling vehicles or outdoor equipment, as well as using solvent-based products (such as paints, stains, or degreasers) during the heat of the day, accelerates chemical evaporation. Handling these tasks after sunset or in the evening when it’s cooler can slow the rate of volatile liquids turning into gas. Also, the absence of active sunlight prevents escaping vapors from immediately reacting to form ozone, giving them time to disperse safely overnight.

•  Choose low-VOC paints and solvents: Look for zero- or low-VOC interior/exterior paints, stains, and household cleaners to limit chemical evaporation into the atmosphere.

•  Ensure gas cans, paint tins, thinners, and cleaning solvents are closed with airtight seals immediately after use. Use EPA-compliant, self-sealing fuel containers that prevent vapor venting.

Mow lawns late in the afternoon or evening: If using gas equipment, mowing during cooler hours reduces the immediate photochemical reaction of emissions.

Energy Conservation:
Reduce peak electricity usage: Setting thermostats slightly higher on hot summer days (e.g., 78°F) cuts down on regional power plant emissions, which are a primary source of NOx​.

Clean Air Action Days:
During local Air Quality Action Days issued by the VA Department of Environmental Quality and Clean Air Partners (https://www.deq.virginia.gov/air-energy/reports; https://www.deq.virginia.gov/air-energy/air-quality-forecast) on high-ozone summer days, the above behavioral shifts carry the highest impact. Signing up for regional AirNow EnviroFlash alerts helps anticipate when to defer gas-powered yard work or shift trips to transit or even when smoke from wildfires may be impacting our region.