Soil Study Summary:

The independent, peer-reviewed soil study, Radioactive Microparticles related to the Woolsey Fire in Simi Valley concludes that while most samples collected were at normal levels;

Some ashes and dusts collected from the Woolsey Fire zone in the fire’s immediate aftermath contained high activities of radioactive isotopes associated with the Santa Susana Field Laboratory (SSFL).

Figure 3: Map of the notable alpha, beta, gamma, and SEM/EDS results

Figure 3: Map of the notable alpha, beta, gamma, and SEM/EDS results

The study determined:

  • The most radioactive sample was found nine miles away from the Santa Susana Field Lab, in Thousand Oaks. The sample was 19 times more radioactive than normal levels. Radioactive samples were also collected from Simi Valley, West Hills and near Oak Park and Agoura Hills.

  • The results of the study determined that 1 out of every 30 samples, or three percent, contained radioactive particles that were chemically identified as originating from the Santa Susana Field Lab.

  • The purpose of sampling is to apply the found percentage to the total un-sampled area. For example, 730,000 people live within ten miles of SSFL. Three percent of 730,000 means that potentially 22,000 people may have been exposed to radioactive smoke and ash during the Woolsey Fire.

  • Because the limits of the study were set for radioactive contamination, we don’t know what type or amount of chemical contamination was released into the community during the Woolsey Fire. Since radioactive contamination from the SSFL reached the community during the fire, it’s reasonable to assume that chemical contamination was also released.

About the Study:

The study Radioactive microparticles related to the Woolsey Fire in Simi Valley, CA was conducted by Marco Kaltofen of the Dept. of Physics, Worcester Polytechnic Institute, and Maggie and Arnie Gunderson of Fairewinds Energy Education. It examined 360 samples of household dust, surface soils, and ash from 150 homes as well as other locations collected in December 2018 through February 2019 by community volunteers who received training in sample and safety protocols.

Press release:

October 14, 2021: Physicians for Social Responsibility-Los Angeles