This story was updated based on a more recent FAQ shared Aug. 11 by the state Department of Toxic Substances Control.
The West Contra Costa Unified School District originally shared a list of nine questions and answers for its Aug. 6 town hall about the toxic chemical PCE discovery that led to the temporary closure of Kennedy High School on Aug. 3. The list, now 23 questions, from the California Department of Toxic Substances Control is posted below. There are separate FAQs with more information about Kennedy, the Omo drycleaner case and the Miraflores PCE plume. It has been lightly edited to include clarifying details and relevant links.
Are students and staff safe at Kennedy High School?
Based on current information, DTSC does not believe there is an immediate risk to the community. Sampling is underway and results will guide possible next steps. To this point, we have not collected evidence that contamination has moved from the soil to the air inside the Kennedy High School buildings. Ongoing tests will show if tetrachloroethylene (PCE) detected in soil has made its way into the indoor air. If that is the case, additional steps may be warranted. In the meantime, DTSC continues its investigation to determine the source of the contamination and the extent of impacts both on the school site and the surrounding neighborhood.
What is happening?
Testing is underway and preliminary results are expected this week. In the meantime, we have no evidence that PCE contamination has moved from underground into the school buildings. The testing and the upcoming results will help provide more answers.
How did we get here?
During studies of a nearby cleanup site in April 2026, DTSC found levels of PCE above DTSC’s residential screening levels in a soil gas monitoring point located approximately 500 feet north of the school. In June 2026, the City of Richmond and DTSC reached out to West Contra Costa Unified School District (WCCUSD) to discuss these results and recommend testing in case mitigation could be added to the new buildings as a precautionary measure. In July 2026 and August 2026, after finding PCE in soil gas on Site, the school district, with DTSC’s support, started testing indoor air, outdoor air, and soil gas at the school. The school district will decide next steps after receiving the new test results.
What is tetrachloroethylene (PCE)?
PCE, also known as perchloroethylene, is a solvent. It has been used in dry cleaning, metal degreasing, and other industrial work. In 2023, California banned PCE for dry cleaning. However, it is still present in many products that consumers can buy. Products with PCE include adhesives, sealants, auto products, degreasers, lubricants, spot cleaners, etc.
What is soil gas? What is vapor intrusion?
Soil gas (also called soil vapor) is the air found between soil particles underground. Some chemicals in soil can form vapors that travel through the soil and collect beneath buildings or along utility pipes. Vapor intrusion is when vapors from polluted soil or groundwater move into buildings and indoor air, where they can be breathed.
What are plumes?
Plumes are the spread of contamination or pollution in soil gas or groundwater. We can find the spread by collecting samples, mapping the results, and comparing the results to screening levels. The plume can be found by mapping where the levels are greater than screening levels. Because soil gas and groundwater move over time, the plume also spreads over time, which is why it can take many years to study.
At what level does PCE in indoor air become dangerous?
To protect people inside homes and school buildings, DTSC uses a value (called “screening level”) that would have virtually no effects even for someone who lives for 26 years, 24 hours per day, 350 days per year in that building. The screening level for PCE (0.46 µg/m3) is so low that the theoretical effect would be to cause one extra case of cancer in one million people.
What are the health effects from PCE exposure in indoor air?
Health effects depend on dose, length and frequency of exposure, and individual sensitivity. Cleanup goals at contaminated sites are usually based on possible longterm exposure, which for PCE can include:
- Changes in mood, memory, attention, reaction time, and vision.
- Harm to the nervous system, liver, kidneys, and reproductive system.
- An increased risk of cancer, such as bladder cancer, non-Hodgkin lymphoma,
or multiple myeloma.
More information from the California Office of Environmental Health Hazard Assessment.
What levels of PCE have been found at Kennedy High School?
Based on current information, we are not aware of any PCE in indoor air at the school. Indoor air is currently being tested and results should be available late in the week of Aug. 10. However, PCE was detected in soil gas underground at Kennedy High School at levels between 5.8 µg/m3 and 5,000 µg/m3. DTSC’s screening level for recommending further investigation is 15 µg/m3 in soil gas. Ongoing tests will help us determine soil gas (under buildings), indoor air, and outdoor air levels of PCE and other chemicals.
What are the preliminary test results from Kennedy High School that came in on July 31, 2026? Where were samples collected?
Six soil gas samples (the air between soil particles, underground) were collected from the school property on July 17, 2026. Three samples were collected just south of Cutting Boulevard in the footprint of future Building A. Two were collected just west of the northeastern parking lot, alongside the eastern edge of future Building A. The final sample was collected near the eastern edge of the future Student Center (and northwest of the Swim Center). In the three samples near Cutting. PCE was either not detected by the laboratory or detected below DTSC’s screening levels. PCE was detected at 2,200 micrograms per cubic meter (µg/m3) in the northern sample from the parking lot and 5,000 µg/m3 in the southern sample from the parking lot. PCE was detected at 39 µg/m3 at the sample near the future Student Center. DTSC’s screening level for PCE in soil gas is 15 µg/m3. This is the level at which DTSC recommends further evaluation of a site including sampling of indoor air.
What prompted DTSC to recommend PCE testing at the Kennedy High School site at this time? Is that standard for any construction?
This was not prompted by the construction work. As part of the investigation of a cleanup site to the north of Kennedy High School, levels of PCE above DTSC’s residential screening levels were detected from a soil gas sampling location approximately 500 feet north of the school. DTSC reached out to WCCUSD to discuss the results and recommended sampling in the event some mitigation was needed and could be added to the new buildings.
How long is the additional sampling expected to take? When do you expect to have results?
The sampling of indoor air, outdoor air, and soil vapor is expected to take three days. Indoor and outdoor air sampling require a full day to collect a representative sample. Soil vapor sampling will start after indoor air sampling is complete. Following collection, the laboratory will analyze the samples for volatile organic compounds (including PCE) on an expedited turnaround. Results are expected by Aug. 13, 2026.
WCCUSD said the tests indicate PCE is under the school site. Does that mean it will move into the air? How is this determined?
On July 31 we received preliminary results confirming the presence of PCE contamination underground. However, based on current information, we have no evidence that the contamination is in the indoor air. To make sure we know what is and is not in the indoor air, the WCCUSD is collecting samples throughout the school campus. Keep in mind that PCE can also sometimes be found in consumer products (e.g., cleaning supplies) and in ambient outdoor air (e.g., from industrial pollution).
Can the public access the testing data?
Yes, DTSC has created a listing for Kennedy High School on our EnviroStor database, which can be accessed at the following link. After the data are reviewed, they will beadded to the page under the “Community Involvement” or “Site/Facility Docs” tabs.
Did the construction at the high school release the PCE into the community’s air?
We are not aware of any PCE releases to community air due to the construction at Kennedy High School. It is important to note that volatile organic compounds are sometimes detected in outdoor air in cities, which is a result of living in an urban area with many pollutant sources. DTSC is aware of some local data within a mile of the high school (at San Pablo Avenue, Macdonald Avenue, and 45th Street), collected in 2023 to 2026, which confirmed there are low levels of PCE in outdoor air in Richmond.
If PCE is found in indoor air, what are the next steps?
If PCE is found in indoor air at levels above DTSC’s screening levels, further evaluation of the data will likely be needed. DTSC will continue to advise and support WCCUSD regarding what possible mitigation might be needed depending on the indoor air levels detected.
How can I remove PCE from indoor air? What are some mitigation options?
There are several ways to stop or reduce the movement of PCE in soil gas to indoor air, whether or not the site is the source. First, cleanup of the soil and groundwater can greatly reduce the potential for vapor intrusion. Second, other actions that mitigate, or decrease the impacts, can include:
- Increasing ventilation inside by opening doors and windows.
- Sealing cracks in a building’s foundation and resurfacing floors with epoxy.
- Adjusting the heating and ventilation (HVAC) system to help limit vapors
entering or accumulating inside. - Using carbon-based air purifiers to reduce the amount of chemical vapors in
indoor air - Installing ventilation systems under buildings to prevent the vapors from moving into indoor air. For example, WCCUSD is working with DTSC to install ventilation systems under the new buildings that are currently under construction, as a precautionary measure.
Should parents, students, and staff be concerned about past exposure?
It is too early to reach any conclusions. Reasonable caution is best at this time. There are many other places where there is more than double PCE underground than at the school, and the PCE did not get from underground into the air inside buildings above it. Still, it is best to wait for testing results.
How long have people been exposed at the school since this has been going on for decades?
It is too early to answer this question about exposure. Test results will help us understand whether indoor air is currently affected. Our work will help determine the source of the PCE. It takes time and special conditions for the PCE vapors to move through the soil and groundwater to get from Point A to Point B. How fast the contamination moves depends on many factors.
I live a couple of blocks away from the school, is my house safe? Is there PCE under my house? How far away from the school should people be concerned?
We recognize the urgency of the question but without a fuller picture of the situation, it is too early to make additional recommendations. We are working to provide more answers as we investigate the source of contamination and its possible movement. We are still in the process of trying to understand if the PCE is getting from underground into the indoor air at the school. There are many other places where there is more PCE underground than at the school, and the PCE did not get from underground into the air inside buildings above it. Every site is different.
What specific criteria or threshold levels led DTSC to conclude there is “no immediate risk” to public health while requiring additional testing?
DTSC’s determination that the levels of PCE found in soil gas at Kennedy High School was based on what is considered immediately dangerous for human health. The maximum level found in soil at the school is 5,000 micrograms per cubic meter (µg/m3), or about 0.737 parts per million by volume (ppm), as of July 31, 2026. The United States Occupational Safety and Health Agency (OSHA) Permissible Exposure Limit (PEL) for PCE in indoor air is 25 ppm. When soil gas moves through soil into indoor spaces, dilution occurs. DTSC uses an attenuation factor to conservatively estimate how much dilution occurs and what levels we would expect in indoor air based on soil gas results. Using the attenuation factor, DTSC determined that anticipated indoor air levels would be significantly below the PEL, and therefore significantly below the “immediate risk”.
DTSC recommended indoor air testing because while there is no immediate risk, there can be health effects related to long-term exposure to PCE. The additional sampling is intended to evaluate if PCE in the soil has moved into indoor air and at what levels. It is important to note that PCE is commonly detected in outdoor air in urban areas, so even a detection in indoor air does not mean that levels in the soil are impacting indoor air. PCE can also sometimes be found in consumer products (e.g., cleaning supplies).
DTSC and WCCUSD will evaluate the results from the August 2026 samples to determine if there is a need for further steps or mitigation.
What is DTSC doing to keep the community safe?
Additional sampling happened last week (Aug. 6 through Aug. 8) A thorough analysis will follow. At this time, we have no evidence that PCE contamination moved from underground into the school buildings. DTSC stands ready to work with WCCUSD and its contractor to evaluate the results of sampling to determine what, if any, additional steps are required.
What or who determines what areas get tested?
DTSC experts worked with WCCUSD and WCCUSD’s licensed contractors to identify locations on the Kennedy High School property where indoor air and soil gas (the air between soil particles underground) should be tested.
In the past, I have heard of PCE being found where a dry cleaner used to be located. Does DTSC know why it’s under the school?
PCE is a solvent commonly used in industrial settings. From the 1940s to 2023 it was used in dry cleaning in California. PCE contamination from use at these sites is common. DTSC is still investigating the potential sources of PCE at Kennedy High School and additional information will be provided as it becomes available.
Is there a known source for the PCE in soil vapor at the high school?
DTSC is still investigating potential sources of PCE. Additional information will be provided as it becomes available.
Is testing warranted in the residential area surrounding the school?
Where we have examined indoor air in the neighborhood, we have not found any vapor intrusion issues. Nonetheless, our analysis will continue. Based on scientific results and recommended guidance, DTSC will recommend indoor air testing if warranted.
