Important Hexavalent Chromium Info

On Thursday 8/28 LA Fire Health Study reported airborne hexavalent chromium nanoparticles—carcinogenic particles small enough to travel 6 miles, infiltrate homes, and accumulate in the body over time—at levels higher than EPA indoor air safety thresholds.

It’s important to understand that while hexavalent chromium is a known carcinogen, the risk comes mainly from long-term, repeated exposure.

Its harmful effects accumulate in the body over time, rather than from a single brief encounter. This means that reducing everyday exposure is critical to lowering long-term health risks. EFRU, with partners Post-Fire and Resilient Palisades, hosted a Q&A to help residents understand the risks and learn steps to reduce exposure. View the recording here. Review the data brief here.

Key take-aways from the Q&A webinar for all:

  • Characteristics of Hexavalent Chromium 

    • Hexavalent chromium nanoparticles and lead are invisible to the naked eye.

    • These contaminants cannot be removed with standard at-home cleaning methods.

  • Samples were From Spring 2025
    The hexavalent chromium that was recently discovered was from air samples taken in March - May 2025. More research is currently being done on more current air samples and LA Fire Health Study hopes to have more current data in late September 2025. In the meantime it’s best to take precautions.

  • Outdoor vs Indoor Levels
    The samples were taken from outdoor air in the Eaton and Palisades Fire impacted areas. The level discovered was below the threshold for outdoor air but above what is safe for indoors. It’s important to ensure your indoor air quality is safe. If you are within, or up to 6 miles around either burn scar, use HEPA air filtration in all indoor spaces.

    • Install HEPA filters in central air systems where possible.

    • If your HVAC cannot support HEPA, upgrade to the highest MERV rating it can accommodate. MERV 14 or 15 is ideal, but some units may only allow MERV 13.

    • Avoid “electrostatic” or “electret” MERV filters, which are less effective for wildfire contaminants.

    • Regional Asthma Management & Prevention information on air purifiers here.

  • Info on Air Filtration Units for your Home

    • Look for highest CADR (Clean Air Delivery Rate) and HEPA filters

    • Avoid add-ons (such as ionizers)

    • Activated Charcoal/Carbon filters in addition to HEPA filters can also capture gases, but are more expensive. 

    • Use this calculator to help you judge the size of the portable air filtration unit or how many units you may need for your home.

  • Outdoor Personal Protection

    • LA Fire Health Study recommends individuals wear a P100 + Multigas respirator when visiting burn scars or highly contaminated areas.

    • Wear an N95 mask in adjacent areas.

    • How to choose the right mask/respirator.

    • Avoid strenuous outdoor exercise in or near burn scars, where airborne contaminants are more concentrated.

    • Children, elders, and pregnant people are especially vulnerable to smoke and contaminant exposure and should take extra precautions.

  • The best practices to recover your standing structure post WUI fire is to

    • Hire a Certified Industrial Hygienist (CIH) to test for contaminants (pre-remediation testing) which should include:

      • an array of heavy metal testing, at minimum RCRA 8 or the full CAM 17 array with lithium in addition

      • TEM testing for asbestos.

    • Hire a remediator certified for lead and/or an abatement contractor depending on what contaminants your home tests positive for.

    • After remediation, have your home re-tested by a CIH to confirm clearance of all contaminants (post remediation testing) – not all remediation is effective and another round of remediation may be necessary

  • Prolonged Exposure & Health Impacts

    • Common short term contamination exposure symptoms may 

      • Headaches 

      • Irritation of the nose, throat, and lungs

      • Wheezing or shortness of breath

      • Persistent coughing or difficulty breathing

      • Itchy hands and feet

    • If health symptoms persist, please consult a doctor.

  • Blood Testing for Hexavalent Chromium 

    • Regular doctors cannot test for hexavalent chromium. These tests can only be done through a research study.

    • Dr. Kari Nadeau from Harvard is working on a project to provide free mail-in blood test kits and will also offer in-person testing in Los Angeles this September.

    • If you’d like updates when testing becomes available, please share your email here.

  • Recontamination Risk

    • Homes and lots can become re-contaminated during rebuilding as airborne particles may resettle on soil and surfaces nearby if the lots with rebuilding activity haven’t been fully remediated. 

  • Other Info to Know