UCLA air quality experts on what you’re breathing in the Boyle Heights fire

Since June 17, a fire has raged through a massive frozen food warehouse in Los Angeles' Boyle Heights neighborhood just east of downtown, smothering the San Gabriel Valley with smoke and raising health concerns. UCLA air quality scientists Yifang Zhu and Suzanne Paulson told reporters about what some of the health risks might be, explained what we know and don't yet know and offered suggestions for staying safer.

Yifang Zhu

A UCLA professor of environmental health sciences and in the UCLA Institute of Environment and Sustainability, Zhu told LAist that materials including plastics, electronics and even rotting meat are likely burning, which means the pollution particles emitted "tend to be highly enriched with toxic organics, toxic metals, that are above and beyond what just normal, day-to-day air pollution would look like. You'll have almost like a double jeopardy in a sense that the levels [of particulate matter] are higher, and the toxicity is also higher." She said that measuring heavy metals or volatile organic compounds requires specialized monitoring equipment, and that she suspects at least some health-harming heavy metals are likely present in the smoke. " I think people really need to take precautions by staying indoors as much as possible, keeping windows closed, running a HEPA or MERV 13 air filter, and wearing an N95 or similar mask."

Zhu told the LA Daily News that particles forming when warehouse components, such as refrigerants and solar panels, burn are so small they bypass the nose and throat and can cause cardiovascular and respiratory diseases in addition to ordinary irritation. "What makes this fire unique is the composition of these particles could be very different. There is a lot of construction materials, solar panels and electronics burning. The resulting smoke can be more toxic. For fires like this, we don't know what has been created with high combustion. The lessons we learned from the January LA fires is we don't look for [components] specifically. And for this fire, we don't have the understanding of what we should be looking for. We need to take precautions. We can't take this lightly. There are lots of unknowns."

Typical wind flow patterns can compound the problem locally, Zhu said. "The onshore winds blow everything to the mountains, but in the San Gabriel Valley, it has nowhere to go, so it stays there. So Pasadena area will be the worst (outside of Boyle Heights and East L.A.)."

The air quality index reports the amount of particulate matter in the air, not what kinds of toxic metals or other substances might be in that particulate matter, Zhu told LA Material. These measurements require specialized instruments. "With fires like this, there are most likely toxins that are not captured by those traditional measurements," Zhu said.

Suzanne Paulson

Paulson, a UCLA professor of atmospheric and oceanic sciences and in the UCLA Institute of Environment and Sustainability, told the New York Times that smoke from a fire is likely more dangerous than everyday urban air pollution, with industrial fires producing particularly potent smoke. Air quality indexes are "set for kind of what we know well, which is normal urban air pollution. When we have smoke, it's probably more toxic," she said.

On KNX radio, Paulson said, "There's no such thing as safe smoke. Any smoke is something that should be avoided. There are millions of compounds that are included in any kind of smoke plume, and they depend on what is burning, and these new industrial fires will have potentially some other more unusual or more exotic compounds, but in all fires, there are lots of things that are very problematic for human health." In the Boyle Heights fire, "It is an unusual situation where the PM levels are not very high, but there is the smell of smoke in the Los Angeles area. If you can smell smoke, then it's definitely a problem and it should be something that should be avoided."