The firefighter pulled the black hose down a hill.
“Good?” she called out.
“All the way down,” a voice responded.
Brea Kirklen kept walking. Below her were the remnants of a homeless encampment in a small canyon by San Diego’s Valencia Park neighborhood. While the county had recently gotten some rain, the sun was again out and baking the foliage on Tuesday afternoon. Kirklen stopped a few feet from the bottom, aimed the hose’s nozzle upward and squeezed a trigger.
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The clear liquid that shot out toward leaves and debris alike was a citrus-based fire retardant called Citrotech that leaders hope will limit the size of any future blazes, including those started by people living outside. Officials began spraying brush along evacuation routes last year and added probable encampment spots to the list in January, all of which should now be less likely to ignite for the next several months.
This approach to fire prevention is new for both San Diego and the nation: The company making Citrotech, Mighty Fire Breaker, only launched a few years ago and is in the early stages of selling cities on the spray, according to records filed with the federal government.
“I’ve never seen anything else like it,” said Tony Tosca, a deputy chief at the San Diego Fire-Rescue Department.
A central part of the pitch is that, in contrast to many cancer-linked chemicals that firefighters have long relied on, Citrotech won’t kill you. It shouldn’t even bother the plants. The company on its website touts the use of “environmentally benign chemicals” that are “safe to use around our homes, schools, pets and children.”
In 2023, the U.S. Environmental Protection Agency gave the company an award for using safer ingredients. One caveat: Mighty Fire Breaker notes online that the award is not the same thing as an endorsement, nor did the EPA conduct its own tests of the spray. The agency instead relied on the company for “information on the product’s composition, ingredients, and attributes.”
The San Diego Union-Tribune asked the organization for a list of ingredients and information about its safety tests. Steve Conboy, founder and president of Mighty Fire Breaker California, responded in an email that the spray is made with water and “food grade constituents” pulled from the EPA’s “Safer Chemical Ingredients List.” He sent a link to the agency’s directory of safe chemicals.
Regarding safety checks, Conboy said they’d run 90 aquatic tests at a lab in Ventura and that the U.S. Forest Service had spent months confirming the substance didn’t hurt trout or mammals. (The forest service did not immediately return requests for comment.)
San Diego’s fire department appears to be the only one nationwide that’s widely employing the spray. Conboy was not aware of others.
San Diego used a nearly $367,000 state grant to buy about 4,000 gallons of Citrotech. Officials estimate that around half has so far been sprayed on more than 40 fire-prone acres, including at least six places where homeless people have been known to camp. (Firefighters wait until after city crews clear the area.) The grant also helped pay for equipment to distribute Citrotech, including a Ford F250 pickup.
All of the sprayed sites can be tracked online through a publicly available map.
Now comes the monitoring. The fire department didn’t create a full environmental impact report before work began — city officials decided the pilot program was limited enough to be exempt from the California Environmental Quality Act — but staffers are now watching to see if the spray has any effect on local plants and animals.
Firefighters will additionally track whether fewer fires begin in areas covered by Citrotech, or if future blazes stop spreading once they reach a treated area. Hopes are high. One video from the company shows a pile of sprayed wood chips refusing to ignite despite being surrounded by roaring flames, and the product’s fans include Jeff Bowman, a former San Diego fire chief who’s now listed as a member of Mighty Fire Breaker’s advisory board.
If results are good, leaders are open to buying more.
Officials say dozens of recent blazes likely originated in encampments, and police officers are now supposed to report any fire-starting material they find outside so supervisors can alert both clean-up crews and firefighters, who should then come by to spray the site, according to acting Lt. Brent DeVore.
Kirklen, the San Diego firefighter, moved the nozzle back and forth over the canyon on Tuesday. The air smelled faintly of hand sanitizer, although some observers said they couldn’t detect any odor. The area had certainly burned before: A short walk away were more than three dozen palm trees with blackened trunks.
After a minute or so, Kirklen switched off the spray, trudged back up the hill and shot out some more. The whole operation took maybe 15 minutes. An estimated 10 gallons had been used.
Sitting in a tent across the street was 33-year-old Geryl Andrews. Andrews had been living around the canyon for about a month, following the loss of a job and some “poor decision making,” he said.
Andrews had started fires at night, but nothing that burned out of control, he added. The name Citrotech was new to him. He hadn’t known that the spray was now on nearby trees, and a reporter asked whether Andrews was still comfortable camping in the area.
“I do want more information,” he said.