How a scientist assesses air quality risk for his kids

Good morning, it’s Tuesday, June 23 and you can expect unseasonably hot weather today. Tomorrow will be worse. 

One of the biggest questions surrounding the Boyle Heights warehouse fire is what, exactly, is burning, and whether traditional air quality monitoring measures are capturing the full extent of the hazards. This sense of the unknown has brought a dark feeling of déjà vu for some, dredging up memories from the January 2025 firestorm. Even those who consider themselves savvy news consumers have struggled to make sense of the official guidance.  

The blaze — which is now in its seventh day — is in a massive cold-storage facility that’s essentially a giant refrigerator, with a solar panel-covered roof and corrugated steel walls filled with dense foam insulation. There were early concerns about the ammonia in the refrigeration system, though that chemical has since been moved offsite, authorities said, but other potential hazards remain.

Yesterday, my colleague Antonia Cereijido wrote about the unique and acute fears of Boyle Heights and East L.A. residents living in the shadow of the crisis with uncertain guidance from the authorities. 

Which leaves people across Los Angeles – those in the plume this time, those for whom the smoke has been intermittent, those who know that there will always be a next fire – with the question: What is the best way to make sense of their air quality risks?

Air Quality Index readings can offer a good baseline, but they don’t necessarily tell the full story in a fire like this, said Yifang Zhu, a professor at UCLA Fielding School of Public Health’s Department of Environmental Health Sciences who studies air quality. 

The commonly-cited AQI measures five major air pollutants, including particulate matter. But AQI readings can only tell us how much particulate matter is in the air, not what toxic metals or other substances might be in that particulate matter. 

“With fires like this, there are most likely toxins that are not captured by those traditional measurements,” Zhu said, explaining that there are gaps in scientific knowledge about what could be generated from burning some of these industrial materials. And that measuring these potential toxins requires highly specialized instruments that are not typically used in a regulatory setting. 

Given the unknowns and the lessons learned from last January’s firestorm (when research suggested that traditional readings could understate the air quality hazards), Zhu advised remaining vigilant even when the AQI readings dip into the yellow, or moderate, range, and continuing to take precautions. 

Sam Silva — an assistant professor at USC who also studies air quality  — has been using the AQI “as part of a larger set of tools” to make decisions for his own family. Silva has young kids and lives in an area where there’s been a lot of smoke.

When his children wanted to go to the playground on Sunday morning, he pulled up the regulatory-grade AQI reading on AirNow and saw that pollutant levels remained “reasonably high.” He decided to keep his kids inside to play after he opened the door and could smell smoke. 

When he checked again in the afternoon, the reading looked a little better and it smelled less smoky outside. 

“Then I sort of made the executive decision that we could go to the playground here where I live,” Silva explained. “I think I would make a different decision if I lived in Boyle Heights.”

The degree to which other parts of the region are affected can also shift with the winds, as L.A. County Health Officer Muntu Davis noted during a briefing Monday. 

“Right now in some areas that were unhealthy yesterday, they're good or they're moderate. And in other areas, they're still very unhealthy,” Davis said. “So, you really have to pay attention to where you are.”

In a riveting new report, my colleague Matt Hamilton takes readers inside the untold story of the eight hours that Palisades fire suspect Jonathan Rinderknecht spent with two detectives, welcoming them into his home and ultimately hiking with them to the scene of the fire.

Matt’s story is culled from hours of testimony given during Rinderknecht’s trial, which remains ongoing.

THE GLENDALE MCDONALD’S BACKSTORY: In a new video for L.A. Material, Greg Ruben goes deep on the first-ever drive-through McDonald’s in a high-rise office building, right here in Glendale.

RECORD ICON: Music mogul Clive Davis — who helped shepherd the careers of everyone from Janis Joplin to Whitney Houston — died Monday at 94.

STICKY ICKY WEATHER: A heat spell will peak Wednesday, accompanied by a heavy dose of humidity and the threat of thunderstorms. 

ASTRO PROBLEMS? After nearly seven decades, the California Institute of Technology is in danger of losing its role managing NASA’s Jet Propulsion Laboratory, the Pasadena Star-News reports. NASA announced plans last month to explore other bidders for the job. 

A NERVE-WRACKING SCRAMBLE: Under their deal with FIFA and the U.S. government, the Iranian World Cup team and its support staff are only allowed to remain in the country for roughly 24 hours at a time, meaning they have to race back to their base camp in Tijuana after games. The Wall Street Journal reports on how the complicated choreography unfolds. 

THE NEW MATCHMAKERS: Forget the awful algorithms — the new way to find love is in the personals sections of local newsletters, which tend “to feel both more grassroots and more curated than the newspaper-based personal ads of yore.”

A Topanga Treehouse Compound

Time to dab a little Patchouli on your wrists, put on some natural fibers and make sure that “Coexist” bumper sticker is fully affixed to your Tesla. Nestled high in the canyon but walking distance to the village, this Topanga abode is the perfect moneyed bohemian getaway. There’s a three-bedroom two-bathroom main house, along with a separate studio and half bath for storing crystals or guitars. The structure feels very Big Sur, with its wraparound redwood decks and woodsy setting. The house is 1,378 square feet and listed for $1.7 million. 

AND FINALLY… A poem to pair with your morning coffee:  “Home to Roost” by Kay Ryan.

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