A preprint study found hexavalent chromium at an average of 13.7 nanograms per cubic meter in air samples taken in recent months
Air quality researchers have detected elevated levels of toxic hexavalent chromium and silver nanoparticles in Pacific Palisades, one of the Los Angeles County communities hardest hit by the January 2025 Eaton and Palisades wildfires, raising concerns about potential health risks for residents and cleanup workers.
A preprint study, co-authored by researchers from the University of California, Davis, and the UCLA Fielding School of Public Health, found hexavalent chromium, or chromium-6, at an average of 13.7 nanograms per cubic meter in outdoor air samples collected in Pacific Palisades and Altadena during March and April 2025. This toxic metal, a known carcinogen linked to asthma, bronchitis, and lung cancer, was detected alongside silver nanoparticles averaging 1.6 grams per cubic meter, with over 90% in particles smaller than 1/1000th the width of a human hair.
While the full health impact remains uncertain, researchers urge caution, noting that nanoparticles can easily cross cell membranes and circulate throughout the body. To reduce exposure, the California Department of Public Health and the LA Fire HEALTH Study recommend using HEPA filters, MERV-13 or higher HVAC filters, and wearing KN-95 or N-95 masks during cleanup in fire-damaged areas.
