In West Oakland, thick tree barriers meant to reduce residents’ exposure to roadside air pollution are set to begin moving from planning to construction, with planting scheduled to start in March along Frontage Road near the I-880 freeway. The Prescott Greening project, long in development according to the report, is now breaking ground as part of a broader effort to surround major roadways in the neighborhood with trees and other buffers.
The initial phase is focused on a stretch of Frontage Road, where the project plans to add dozens of trees that start at about 10 to 12 feet tall and are expected to grow to roughly 40 feet. The project’s timeline calls for completing the work within about five months, after steps to prepare the site are carried out first.
Art Garden Design, the landscape designer overseeing the planting, will begin in the coming weeks by removing older trees, upgrading irrigation, and regrading the site. Once that preparation is finished, workers are expected to start planting trees in March, with the project continuing through the following months.
In describing the approach, Art Garden Design owner Alana Corpuz said the corridor reflects “broken infrastructure” tied to neglected maintenance and that nearby activities contribute to air pollution. She said the goal is to create a tree buffer with enough depth to reduce off-gassing for nearby residents, pointing to waste management on 10th Street, a skate park, and other sources of emissions and burning in the area.
Hyphae Design, an Oakland ecology firm that developed the planting concept, said it designed the project “with foliage from the ground up” to form a canopy where pollution can get stuck or drift upward into the atmosphere rather than returning into neighborhood areas. Hyphae’s design plan specifies both tree species and shrubs, including fern pines, long-leafed yellowwoods, and Japanese blueberry trees, as well as California lilacs, manzanitas, and bottlebrushes.
Brent Bucknum, Hyphae’s director, said research behind the dense planting pattern found it can reduce roadside pollution by “between 20% to 40%.” He contrasted that with what he said is a “1% to 4% drop” from trees placed randomly and spaced apart, and he said Hyphae’s work in Louisville has already led to a 25% drop in air pollutants.
Bucknum also said the project is intended to keep delivering air-quality benefits as California’s vehicle fleet shifts to more electric power. He said some of the most harmful pollution comes from ultrafine particles associated with brake and tire wear, and he argued that attention should not focus only on trucks. “We’re learning that really fine particles are more impactful health-wise because they move through the blood-brain barrier and through the lungs,” Bucknum said. “A lot of people want to just blame the trucks, but it’s actually passenger vehicles and the number of them that are going by this location in West Oakland that has a bigger impact.”
The Prescott Greening plan is being presented as a pilot within a larger strategy to green other parts of West Oakland and potentially extend to highly polluted areas in San Leandro. The planting along Frontage Road is listed as the first of three components, with Hyphae saying that if the project receives additional funding, teams would work with Caltrans on greening land next to I-880 and incorporate dense tree plantings into road-diet construction projects where vehicle lanes and parking are reduced and pedestrian and bike infrastructure increases.
The effort’s background traces to residents’ longstanding complaints about polluted air in West Oakland, with the report describing how pollution levels rose as highways were built around the area and the port expanded. Hyphae said it later developed and refined a master plan—Adapt Oakland—using technology including lidar and computer modeling to understand where pollution accumulates and how wind patterns spread contaminants, including at the 7th Street and Frontage Road interchange near I-880.
Hyphae said modeling helped identify the area as a major source of pollution entering the Prescott neighborhood, and it pointed to a Kaiser Permanente cancer study in the vicinity, which it said found a correlation between emissions and health impacts for residents of a nearby senior housing complex. Bucknum said funders including the Metropolitan Transportation Commission, the Alameda County Transportation Commission, the Port of Oakland, and the Sustainable Transportation Equity Project supported the planting based on that work.
Hyphae designer Mei Visco described the modeling analogy behind the project’s focus on proximity to emissions, saying that people right next to the freeway were far worse off than those even a few blocks away. Bucknum said the organization is writing a report it hopes to publish in the spring, and that it will argue that $20 million could significantly expand the project to reduce more pollution affecting West Oakland, with the report intended for presentation to Oakland, the port, and the county transportation commission.
Beyond the planting itself, Bucknum and Visco said routine maintenance may be central to maximizing any air-quality gains, given that tree health and canopy density depend on ongoing care. They said they have told Caltrans that when freeways are built through environmental justice neighborhoods, maintenance needs to be approached differently than in other locations.
Hyphae said it is in conversations with the state about similar projects in Stockton and Los Angeles, and that it is also modeling the costs of endowment funding to support long-term upkeep. For the Prescott Greening project, Hyphae and Art Garden Design are developing a three-year maintenance plan with Wood Street Commons, the West Oakland nonprofit, for regular weekly volunteer cleanups.
“If we want to be able to have a better future, a cleaner future, if you want to be able to prevent pollution from getting to people, to lower the heat island, you have to take care of the trees,” Visco said.