Toxic chemicals often found in trace amounts were detected in much higher levels a few days after the Eaton fire in Altadena and Pasadena ignited, underscoring warnings that wafting smoke from urban fires can contain unusually high levels of harmful toxins, Caltech researchers reported on Friday, Jan. 31.
Monitoring an air quality site in Pico Rivera, Caltech researchers reported spikes in chlorine, lead and black carbon from the evening of Jan. 7 — the night the fire erupted — through Jan. 11. The chemicals were found mixed with more common particulate pollution, known as PM2.5, which are air particles 2.5 microns in size or smaller that can also come from ordinary chimney smoke and tailpipe emissions.
Lead levels on Jan. 9 on average were 100 times higher than the typical range, while chlorine was 40 times higher at the peak, and average black carbon levels were 8 times higher than pre-fire concentrations, said Haroula Baliaka, a graduate student in environmental science and engineering at Caltech who analyzed the data.
She said the high lead levels on Jan. 9 were surprising, so much so that she tripled checked the data.
“We did see unusually elevated pollution levels for lead, especially,” she said during an interview on Friday. Many of the 7,000 homes that burned were older homes painted when outdoor paint containing lead was more common, she said.
Lead, listed by the U.S. Environmental Protection Agency as a toxic air contaminant, has been reduced over the decades. Lead levels in air in the United States have improved dramatically since lead was removed from gasoline due to federal government regulations requiring a switch to unleaded gasoline.
Lead exposure can interfere with brain development and damage the nervous system.
When it comes to chlorine found at higher levels after the fires, the sources could be plastics, pool supplies and PVC in pipes, researchers said. And black carbon is a product of incomplete combustion of buildings, fuels, automobiles and wood in fireplaces, Baliaka said.
During those first few days, smoke from the Eaton and Palisades fires degraded the air quality in a wide swath across the South Coast Air Basin, the researchers reported. Smoky air traveled more than 100 miles, reaching Catalina Island, they reported.
Beginning on Jan. 9, researchers reported PM2.5 levels were declining, and on Jan. 12 the levels of air pollution returned back to pre-fire levels, explained JPL science system engineer Sina Hasheminassab, who specializes in air pollution monitoring, during a webinar.
“Rain events further helped reduce PM2.5 levels,” he said.
The Air Quality Index (AQI) showed most of Southern California’s air was listed as moderate on Friday, with a small pocket of unhealthy air for sensitive people in Riverside, Rialto and Colton. Air quality was good in the Angeles National Forest and most of the Big Bear area.
The AQI accounts for smog components such as ozone, PM2.5, carbon monoxide, nitrogen dioxide and sulfur dioxide. But it does not account for toxic chemicals or metals that the Caltech and JPL researchers found in real-time measurements during the few days after the fires started, said Hasheminassab.
The Pico Rivera site is connected to a more sophisticated, nationwide air monitoring network and is equipped with advanced monitors to measure toxic air contaminants, he said. “Very few resources can in real time measure those chemicals,” he added.
Caltech professor of geochemistry Francois Tissot tested the soot and dust that accumulated on the inside window sills of four Caltech buildings in Pasadena a few miles south of the Eaton fire. Dust samples contained more lead and cadmium, another metal, than ash samples. The indoor dust had elevated levels of lead but many of the samples tested found lead at or below EPA acceptable levels.
He advised owners of homes and offices to clean window sills with a wet cloth. He said simple, basic cleaning removes 90% of heavy metals. When cleaning an indoor space, wear gloves and put on an N-95 mask, he said.