The giant warehouse that burned for eight days in mid-June in the Boyle Heights neighborhood of Los Angeles had used thousands of pounds of anhydrous ammonia to cool the facility.
Anhydrous ammonia is a common refrigerant used in cold storage warehouses. But it is also toxic, and if it leaks, it can cause respiratory irritation; in large doses, it can lead to lung and eye damage and even death. In 2020, a contractor at a Lineage Inc. facility in Statesville, North Carolina, was killed and others were injured during an ammonia release.
On June 17, the first day of the Boyle Heights fire, Los Angeles Fire Department Chief Jaime Moore told CBS LA that ammonia had escaped from the facility. “We believe an ammonia line was then compromised, because we had a large powerful stream of ammonia coming out,” Moore said as clouds of smoke and flames rose behind him. Moore said the fire department had ordered residents to close their windows and doors and shelter in place.
Since then, Lineage and the fire department have provided few details to the public about what happened. Lineage has denied that a leak occurred and has said ammonia was removed from its warehouse during the blaze. In July, Moore later reportedly said no ammonia was detected, but the fire department has not released results of its monitoring for the chemical or for other toxics during the fire.
More recent ammonia readings raise a separate question: Why is ammonia, which can remain in the air for about a week, being detected more than a month after the fire? In recent weeks, the South Coast Air Quality Management District has reported levels of the contaminant at a local elementary school about a half mile from the warehouse that far exceed average exposures for the L.A. area. Lineage has reported even higher levels in fine print on the company’s website. On July 10, for example, one of the company’s readings taken less than 100 feet from peoples’ homes detected ammonia at 13,000 parts per billion more than double the level the state of California considers safe for short-term exposures. Another reading that also exceeded the safety guideline at 7,000 parts per billion. Several other readings — one measured as recently as Aug. 6 — were also elevated.
Lineage spokesperson Melanie Mendoza didn’t respond to Capital & Main’s request for comment on ammonia levels that the state considers unsafe. She had previously denied in an email that there were any “measurable ammonia concentrations” detected in the community. She later walked that back, saying ammonia levels had not exceeded the state threshold for acute exposures. “At no point has ammonia reached a level that would pose a health risk,” she said.
There is still no official report of what happened during the fire. But newly obtained fire department records offer a minute-by-minute view from the perspective of first responders as they confronted the blaze in June. A computer-aided dispatch log, obtained by Capital & Main through a public records request, showed that firefighters identified “an active amonia [sic] leak” on the roof of the building at 3:12 pm — about 35 minutes after a 911 caller first reported the warehouse fire.
A minute later, the log reports the appearance of “an unknown vapor cloud” rising over the warehouse. Moore later reportedly said the cloud was the result of cold air mixing with hot air and did not contain ammonia.
By 3:25, the log again notes an ammonia leak and says that firefighters would battle the blaze in “defensive mode,” or from outside the structure, likely because it was considered too dangerous to go inside. At the same time, the fire department ordered residents to close their windows and doors, shut off air conditioners and shelter in place.
Los Angeles Fire Department hazardous materials crews monitored the air for ammonia and other toxic gases during the fire. But the department has not disclosed its findings. Fire Department spokesperson Branden Silverman told Capital & Main in a statement that “collecting it will take some time.”
A spokesperson for Mayor Karen Bass didn’t respond to Capital & Main’s questions about the facts that caused Moore to change his opinion about the ammonia release or about the department’s delay in reporting the results of its air monitoring during the fire.
Lineage reported a “potential spill” to the California Office of Emergency Services about 90 minutes after the fire erupted, according to a hazardous materials spill report. By law, even potential releases of hazardous materials such as ammonia must be reported to state and federal authorities. The report — provided to Capital & Main by the Office of Emergency Services — paraphrases a Lineage representative, whose name is redacted, as saying: “There is no potential release of anhydrous ammonia and no concerned [sic] of release.”
To date, there has been no publicly released investigation of whether or not a hazardous ammonia leak occurred. But on Aug. 4, Los Angeles Public Press reported that the U.S. Environmental Protection Agency demanded that Lineage answer questions about a possible ammonia release. The agency gave Lineage an Aug. 17 deadline to produce a “detailed description and timeline” of what happened, to disclose any contaminants that were released and the calculations made to make that determination. The agency also asked for the results of air monitoring that was conducted when firefighters initially reported an ammonia leak and in the days that followed, as well as any emergency response measures taken to stop or minimize hazards it may have posed.
Mendoza said the EPA inquiry is “the agency’s standard response to the notifications Lineage made in accordance with the law.” She added, “Lineage will continue to provide the EPA with all requested information.”.
Publicly, Mendoza and other company representatives have provided little information and have denied there was an ammonia release.
On Aug. 6, Dominic DiCarlo, Lineage vice president of global safety and compliance, said, “We’re highly confident that ammonia from the refrigeration system was not compromised.” DiCarlo cited tests the company and local fire officials conducted of the refrigeration system and statements by fire officials. He also said “no ammonia readings were picked up outside the facility.” DiCarlo didn’t specify when the readings were taken.
DiCarlo was testifying at a South Coast Air Quality Management District hearing, which was held to resolve odor complaints resulting from the warehouse cleanup. The issue of community exposure to toxic chemicals came up repeatedly during the two-day proceeding. The company agreed to 93 conditions to mitigate odors and reduce residents exposure to toxics, including additional “fenceline monitoring” at the warehouse site for ammonia and other contaminants and notifying AQMD and the community if readings exceed state or federal thresholds.
Mohan Balagopalan, one of the five-member panel that presided over the hearing, in closing remarks, expressed skepticism about the company’s assertion that there was no ammonia release during the blaze. “I would take that with a grain of salt,” he said. Balagopalan, a retired AQMD manager and a toxics expert, said he thought the ammonia hazard was likely one reason firefighters battled the fire from the ground and the air via helicopters instead of remaining on the roof.
Angelo Bellomo, a retired Los Angeles County Department of Public Health deputy director, said an investigation is required to discover whether there was a hazardous materials leak. But he said first responders’ observations can provide important information. “If they say there is an active anhydrous ammonia release, you don’t have to drill them over that,” he said, adding that ammonia is easily detectable because of its distinctive odor.
A month after the fire erupted, there are renewed concerns about community exposure to ammonia. Ammonia can remain in the atmosphere for a week, according to the federal Agency for Toxic Substances and Disease Registry. But five weeks after the fire, AQMD air monitoring found ammonia at “much higher than typical levels in the air in urban Los Angeles,” according to Jill Johnston, an associate professor of environmental and occupational health at the University of California, Irvine, who has reviewed the data. The AQMD monitoring was conducted outdoors at Eastman Elementary School, about a half mile from the warehouse.
The Los Angeles Unified School District’s Office of Environmental Health and Safety also found elevated ammonia levels inside a classroom at the school according to an Aug. 10 report, which found elevated levels in a classroom at the Eastman Early Education Center and in one at Humphreys Avenue Elementary School.
Ammonia “can cause wheezing, coughing, irritate the eyes, nose and throat, exacerbate asthma or COPD,” (chronic obstructive pulmonary disorder), Johnston said, adding that “kids in particular tend to be more vulnerable to adverse impacts.” Boyle Heights residents have told Capital & Main they’ve experienced sore throats, skin rashes, headaches, irritated eyes and worsened asthma, among other symptoms during the fire and its aftermath.
Two of Lineage’s own measurements — conducted by private contractor Onterris — registered ammonia levels that far exceeded safety guidelines. The state Office of Environmental Health Hazard Assessment advises that ammonia levels at 4,500 ppb or higher can cause adverse health effects during short-term exposures. One of the readings, on La Puerta Street — no more than about 50 feet from homes — was more than double the state standard at 13,000 ppb, while the other registered 7,000 ppb. Several other readings by the company showed elevated levels near Boyle Heights homes as recently as Aug. 6, when ammonia levels reached 3,000 ppb near the warehouse on Prado Street and as far back as July 3, with a 4,000 ppb measurement at the facility fenceline about 50 yards from Indiana Street.
It is not unusual for corporations like Lineage to hire their own environmental testing firms. But Onterris, which until April 2026 was known as the Center for Toxicology and Environmental Health, has earned a reputation for producing health and environmental assessments that favor the companies that hire it. In 2023, when a train derailed in East Palestine, Ohio, and spilled dozens of hazardous chemicals that caught fire, ProPublica and the Guardian reported that CTEH tested residents’ homes with hand-held monitors and told them the air was safe. But independent experts the news organizations consulted said the monitoring devices were insufficient to detect all the chemicals that may have been present and the monitoring period was too short to capture accurate results.
In 2010, two then-U.S. Congressmembers, Rep. Lois Capps, D-Calif., and Rep. Peter Welch, D-Vt., who is now a U.S. senator, cited the company’s track record as they urged Tony Hayward, then-CEO of BP PLC, not to use CTEH to assess the health of cleanup workers in an oil spill in the Gulf of Mexico. “CTEH has a history of being hired by companies accused of harming public health and releasing findings defending the corporate interests of those that employ them,” they said in a letter.
Ontario’s media representatives did not answer a Capital & Main email inquiring about the company’s environmental track record.
In Boyle Heights, the source of the ammonia detected weeks after the fire broke out isn’t known. The company stored between 10,000 and 24,999 pounds of ammonia in the warehouse daily, according to a report posted by the California Environmental Protection Agency. At the Aug. 6 hearing, DiCarlo said the company had removed all of the ammonia from the facility —more than 10,000 pounds – from the facility.
But Johnston said the elevated levels in the environment could suggest that some ammonia remains in the burnt remnants of the warehouse. Rotting meat that still has not been removed from the structure could also emit ammonia, she said.
Boyle Heights residents may have an opportunity to question Lineage about whether there was an ammonia leak and how extensive it was. In its letter to Lineage, the U.S. EPA says the company could be required by federal law to hold a public meeting within 90 days of “a reportable accident,” depending on what substances were released. Capital & Main asked Mendoza if such a meeting is planned, but she didn’t respond before this story was posted.
Residents may still face barriers in getting the information Lineage provides in answer to the EPA’s questions. EPA spokesperson Julia Giarmoleo told Capital & Main in an email that “documents are available to the public in response to a FOIA [Freedom of Information Act] request,” which can take weeks or months to be fulfilled.
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