Following best practices from previous federal post-wildfire soil-testing efforts, The Times collected samples from residential properties in Altadena and Pacific Palisades.

Representative soil sample testing done in a Los Angeles County Public Health study found a higher percentage of samples with lead levels above health-based screening thresholds taken from parcels ...

Testing shows toxic heavy metals like lead, arsenic, and mercury at levels hazardous to human health, with children and workers bearing the brunt of the risk.

Adam Love with Roux Inc., the firm which conducted the soil sampling study for the county, said soil was collected in 200- or 500-milliliter jars and taken from the first three inches of soil.