Hexavalent Chromium in West Rancho Dominguez


In June 2019, South Coast AQMD (SCAQMD) revealed higher levels of hexavalent chromium or chromium 6 in an industrial part of West Rancho Dominguez (WRD), an unincorporated community in Los Angeles County (see Figure 1). SCAQMD has been investigating the source of these emissions and working with facilities to reduce them.

SCAQMD monitors in West Rancho Dominguez
Figure 1 - SCAQMD air monitors in West Rancho Dominguez

What has been found through air quality testing?

At the beginning of the SCAQMD investigation, monitors found that levels of chromium 6 in the industrial area of WRD were 50 to 100 times higher than average levels in the Los Angeles Area. However, these levels have decreased substantially since 2019. Ambient chromium 6 levels have continued to show a downward trend during 2020-2021, with occasional elevated levels reported in the industrial area on certain dates due to equipment repairs, loss of power for emission control devices, and other malfunctions. Current ambient chromium 6 levels continue to remain above typical levels for the region (0.04 to 0.06 ng/m3). Please see Figure 2 below.

Figure - West Rancho Dominguez Hexavalent Chromium in Outdoor Air April 1, 2021 - March 31, 2022
Figure 2 - Hexavalent Chromium Monthly Monitoring for West Rancho Dominguez

What is being done to address the high levels of chromium 6 in WRD?

Details about the SCAQMD investigation, including air monitoring data and enforcement actions can be found in West Rancho Dominguez Emissions Investigation page. A joint SCAQMD-DPH fact sheet on the air pollution investigation has been developed; and planned outreach activities are pending resolution of the COVID-19 crisis.