Follow-up air quality testing in the Altadena and Pacific Palisades areas has found that chromium-6 (Cr6 or hexavalent chromium) levels have decreased and are currently back to the typical low levels detected in Los Angeles.

• Background: In August, the LA Fire HEALTH Study consortium reported that it had detected elevated levels of chromium-6 (Cr6) nanoparticles in air samples that were taken in March, April, and May in the Altadena and Pacific Palisades areas. These findings were published in a preprint journal article and in a Data Brief on the LA Fire HEALTH website.
• Testing in September found that those levels have decreased and are currently back to the typical low levels detected in Los Angeles. This was consistent in both the mobile measurements and stationary air samples we collected. South Coast AQMD found similar results with their stationary samples, also collected in September.
• This is good news for the community. Our interpretation of the measurements is that chromium-6 weathered back to its more stable and less toxic chromium-3 form over time. Measurements of total chromium in the air are consistent with this interpretation.
• Further investigation is still needed to determine the source of the Cr6 in earlier measurements, to help us understand how to prevent more exposures in future wildfires, and to ensure that future debris removal or construction activities in the area do not cause additional exposures.

View the Updated Data Brief

Read more about the updated findings in the new Data Brief 7.1 Addendum.