Last week the Pasadena Unified School District released the first batch of results from soil testing done at all district sites. The results were in line with Los Angeles County testing, which found elevated lead levels in and around the Eaton fire burn scar.

Testing found 18 PUSD sites with an elevated level of harmful substances present in soil samples. The sites included: Allendale, Altadena Arts Magnet, Blair, Field, Jefferson, John Muir, Longfellow, Madison, Marshall, Octavia Butler, San Rafael, Washington STEM, Webster, Cleveland, Hodges, LaCasita, the District Service Center and the district’s main office.

In the process, questions emerged about the testing. We pursued some answers. Here is a short Q&A bring together some insight gained during the reporting.

Is there a way to tell whether the contamination found in PUSD soil testing came from the Eaton fire or was previously present in the soil?

USC Professor of Earth Sciences and Environmental Studies Josh West said that question is one of the toughest when it comes to analyzing contaminated soil. Without data from before the fires there is not a good way to know if the lead or other materials came from fires or was already present in the soil via another source.

“For context, there are a lot of sites across the L.A. area with elevated lead in soils, because of the history of contamination from leaded gasoline, paint, and industry,” West said in an email.

What screening criteria did PUSD use to determine what test results needed to be flagged?

Pasadena Unified School District said it used California lead screening levels set at 80 mg/kg of concentration. By contrast, the federal standard set by the EPA is 200 mg/kg for lead concentration.

I’m a parent. What do I need to know to keep my kid safe?

West said parents should emphasize cleanliness with their children because the main pathway for exposure for most soil contaminants is playing outside, then eating food or sticking hands in the mouth. To prevent this, children should wash hands regularly after playing outside, not eat with dirty hands and not track dirt into the house.

What is PUSD doing on campuses where contamination was present?

In response to the initial findings PUSD announced it would take the following steps:

-Areas with impacted soil will be closed until investigation and remediation is complete. The areas will be clearly marked and secured to prevent access.

-Remediation will be completed before the new school year starts.

-Additional testing will take place before and during the remediation process.

Will the district be releasing more test results?

PUSD said that the results released last week were merely the first phase of testing. Testing for additional harmful substances is still pending and updates will be posted on the district’s website.