Is it safe to eat from your garden after the Boyle Heights warehouse fire?
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- After an eight-day blaze at a Boyle Heights warehouse, toxic ash may have tainted backyard food gardens. Experts urge caution but say contamination may be limited.
- Gardeners are advised to strip away contaminated topsoil, water gently, cap beds with clean mulch or straw and avoid leaf blowers that can spread hazardous particles.
- Most fruits and root vegetables can be salvaged with vigorous washing and peeling, while lab testing and bioremediating plants help eastern L.A. gardens recover from industrial and fire pollution.
After the eight-day-long fire in a 500,000-square-foot Boyle Heights warehouse, eastern Los Angeles residents are contending with putrid smells, soot and potentially hazardous airborne chemicals after heavy plumes of smoke spread throughout the city. But those who grow food in nearby neighborhoods may also be wondering: How will the fires affect the plants and produce in my garden?
The Boyle Heights warehouse, owned by Lineage — a global temperature-controlled storage facility operator — housed 85 million pounds of frozen food and other products. In the days since the fire, local emergency visits for smoke inhalation and throat pain spiked while agencies still scramble to measure the amount of PM 2.5 — harmful fine particles — and heavy metals, like lead and arsenic, in the air.
According to researchers, any toxic airborne chemicals would likely stem from the charred foam insulation, metal exterior, burned solar panels and any lithium batteries that might have been present inside the warehouse.
On a recent sunny afternoon, volunteers took part in a collaboration between Farm Party and the Solano Canyon Community Garden.
After a fire, heavy metal particles can spread through ash and smoke over gardens and inhibit growth, said Olukayode Jegede, an agricultural toxicologist and assistant professor at UC Davis. Since the warehouse fire is so recent and cleanup has just begun, Jegede said the precise impact on gardens can’t be measured until comprehensive soil tests are conducted in the area.
While the L.A. city government hasn’t announced plans for soil testing, the Contaminant Level Evaluation and Analysis for Neighborhoods project at USC is offering free contaminant testing for Boyle Heights and East L.A. residents. Residents can collect soil samples and deliver them to Boyle Heights City Hall and other locations for an evaluation of lead, arsenic, chromium and mercury levels.
The good news is produce, plants and roots can still be preserved. According to Jegede, many of the soil tests conducted last year in the Altadena area after the Eaton fire showed that gardens and poultry were not as contaminated as one might expect.
“Quite a number of the soils we tested [in Altadena] were not really contaminated,” Jegede said. “We weren’t seeing many soils with concerning elevated levels of metal, so gardeners should not be too alarmed when these things happen.”
Nevertheless, there are several measures that gardeners can take to keep themselves, their children, plants and produce safe from potentially harmful contaminants stemming from the fire. Researchers, gardening experts and horticulturists offered some guidance on the handling, recultivation and cleanup that can keep you and your garden in good health.
The Eaton and Palisades fires likely made polluted soils worse, but soil experts say bioremediation may be an alternative to scraping, especially for gardeners.
How do I remove ash and contaminants from my garden?
Altadena horticulturist Leigh Adams said Boyle Heights plants and produce already live in a difficult environment, surrounded by industrial warehouses that spread contaminants daily.
“That area has been used industrially for 100 years, and the soil is impacted by many, many, many things,” Adams said. “Low-income neighborhoods and gardens usually don’t have a lot of resistance against dominant manufacturing.”
This means that the contamination of gardens in eastern L.A. won’t be as catastrophic as compared with those in Altadena, a more suburban environment, Adams said. But fallen ash still poses major health risks if ingested or inhaled.
An advisory from University of California Agricultural and Natural Resources last year recommended suiting up in an N95/KN95 mask, long sleeves, pants, close-toed shoes and gloves before attempting to deal with ash in the garden to limit exposure to potentially toxic contaminants. The advisory added that individuals should make sure all of this gear is cleaned thoroughly before bringing it back inside.
Once in the proper gear, Adams recommends removing the top two inches of topsoil from gardens, where the highest concentration of contaminants will settle after a fire. Using a plastic bag to collect the soil and disposing of it in the garbage — not green yard waste bins — will help to reduce the spread of airborne chemicals.
Gardeners with raised beds are advised to remove approximately six inches of soil, because excess ash can raise the pH level and prevent nutrients from soaking into the soil bed.
After this, watering the garden gently but plentifully will help to promote soil health and get rid of most of the ash present on plant leaves and stems. Adams said replacing the top two inches of soil with store-bought mulch or straw will help to contain any remaining ash and prevent it from spreading any further.
Experts say to avoid using leaf blowers if ash is present in the garden because they can send particles airborne. Doing so will increase the likelihood of heavy metal particles, which can carry lung irritants and carcinogens, being spread and inhaled.
Is it safe for me to eat produce from my garden?
Several studies, including one from the UC Cooperative Extension of Sonoma County, have shown that consuming produce in a fire-affected area poses minimal health risks.
Jegede said most root vegetables like potatoes and carrots, along with any fruit that has an outer layer, can be washed to remove potential contaminants, even if they were covered in ash. Peeling the outer layer of your produce can also help to reduce potential risks, he said.
Lettuce and other leafy foods with multiple layers pose a higher risk of contamination, but with a vigorous wash and peeling the outer layers, even the greens can be saved. The County of Los Angeles Department of Public Health recommends soaking leafy produce and fuzzy fruits like peaches in a 10% white vinegar and 90% water mixture.
Jegede said if the leaves or fruit are too delicate to wash or ash is still visible, it would be best to dispose of the produce.
How can I tell if my soil is contaminated?
After ridding your garden of visible ash, you might wonder how to tell if your plants will still thrive in the soil.
At-home soil tests that measure for alkaline, fertility and pH levels are widely available and can be purchased for $15 to $100 (for more detailed results) online. But Jegede said these tests can’t tell the full story of soil health.
Comprehensive soil testing is “something you can’t do properly at home,” Jegede said. “In labs, we are testing for metals like lithium and zinc, stuff that an at-home test will not show … If it comes to the point that you’re worried about your soil, I would just send it out to a lab.”
Wallace Laboratories in El Segundo, Babcock Laboratories in Riverside, Waypoint Analytical in Anaheim and other labs offer more detailed soil tests that measure heavy metal particles in addition to other fertility factors. Prices at Wallace Laboratories can range from $115 to $295 for a complete compost test.
The soil below two inches should be unharmed, Adams said, so long as new compost is set and plants are watered plentifully, which will promote natural biological cycles.
“What you’re doing is capping the soil, so that moisture stays in there, and instead of being dirt, it’s a living system called soil,” Adams said. “The more carbon we can get into our soil, the better.”
What can I do to help my soil recover?
For the last 12 years, Adams has been working with Metabolic Studio, a Los Angeles-based art and research hub focused on environmentalism, on methods for bioremediation, the practice of using additional fungi, plants and compost to decontaminate ash and break down contaminants.
Adams said straw, mushrooms, corn, rye and sunflowers are great bioremediators that can help to repair damage to soils. She said certain samples she’s worked on with Metabolic Studio have gone from testing at high heavy metal levels to nearly contaminant-free.
But for a more immediate fix, wash your produce, water your plants and have a little patience during ash cleanups. Your garden should look better in no time, Adams and Jegede said.
