Actively Monitoring Air Quality

Air Quality Monitoring Results  |  Our Approach  |  Glossary  |  Explainers

Ascon workers
Weekly onsite and offsite air monitoring for week of December 11th
Onsite Dust Monitoring Results

February 26th - March 3rd

Important note: Air quality was safely below conservative health-protective screening levels.

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Ascon team member collecting data from air monitoring trailer offsite in 2019.

Dust Monitoring Results

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VOC Monitoring Results

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To view archived air monitoring results posted by DTSC on Envirostor, click on Community Involvement Documents, and scroll to Updates and Information.

The following is live wind and weather data collected onsite. Seasonal rainfall totals are recorded from January 1 to December 31 each year.

Air Monitoring Approach

During cleanup activities, we are working to ensure the health and safety of the community by protecting air quality at the Site and in the local neighborhood.

Until remedial fieldwork at the Ascon Landfill Site resumes, our team is monitoring for volatile organic compounds (VOCs) and dust via:

  • Onsite Monitoring: Three air monitoring stations for dust and five air monitoring stations for VOCs are located around the Site perimeter, including one upwind dust station and one upwind VOC station. Dust concentrations are measured, with 24-hour averages reported. Samples for VOCs are sent to a state-certified lab for analysis and data validation.
  • Offsite Monitoring: In advance of October 10, 2023 offsite monitoring results from five air monitoring trailers for dust and VOCs deployed at locations in the surrounding community is available. Dust concentrations were measured, with 24-hour averages reported. Samples for VOCs were collected and sent to a state-certified lab for analysis and data validation. The results were compared to health-protective screening levels established by the California Office of Environmental Health Hazard Assessment (OEHHA) and the Agency for Toxic Substances and Disease Registry (ATSDR), as well as with onsite monitoring results to identify any potential impacts related to Site activities. Offsite monitoring will resume with restart work.

When remedial fieldwork resumes, we will monitor for VOCs, polyaromatic hydrocarbons (PAHs), odor, dust and metals. Learn more about air monitoring during remedial fieldwork by clicking here, and about what affects air monitoring for dust measurements by clicking here.

The Department of Toxic Substances Control (DTSC) has approved a pause in Ascon offsite air monitoring while there is no excavation work occurring onsite. Air quality monitoring data gathered since September 2019 shows air quality has been safely below health-protective screening levels, including during active work. Onsite air monitoring at the site perimeters will not be paused, and continues 24 hours a day, 7 days a week.

Air monitoring screening levels were approved by the Department of Toxic Substance Control (DTSC) and reviewed by South Coast Air Quality Management District (SCAQMD). Screening levels take several factors into account, including the type of substances that may be present, the concentration in the air and how long the exposure lasts. The levels are set to protect potentially sensitive members of the community (e.g., children, pregnant women, those with health concerns) and are for both short-term and long-term exposures, such as daily exposure over a lifetime.

While remedial fieldwork is paused, if the lab analysis results exceed health-protective screening levels for VOCs, we will:

  • Determine the source and necessary mitigation actions.
  • Share with DTSC and the community via this website.

Example of Health Protective Screening Levels Used for Monitoring Benzene

Benzine Graphic

We are taking several actions at the Ascon Site to help control odors. They include:

  • Evaluating feasibility of tenting and enclosure designs to utilize for soil work.
  • Applying plastic sheeting, soil, foam and water.
  • Increasing measures to stabilize soil stockpiles, including a non-toxic odor suppressant material that binds to loose soils and forms a shell resistant to wind and erosion.
  • Installing a 16-foot barrier fence along northern and eastern portions of the Site.

See our Safety Commitment to learn more.

Air monitoring is occurring at the following onsite locations, offsite locations have been removed but data is available from these locations up to October 10, 2023 until remedial fieldwork resumes:

Ascon Site Map
* Map is for illustrative purposes only. Boundaries and locations shown are approximate.

Air Monitoring Glossary

An amount of a substance established by regulatory agencies that is protective of public health. Action levels are used during the work at Ascon to guide mitigation actions, stop work actions, and prompt increased actions to control potential odor, emissions or dust.

The air occurring at a particular time and place outside of structures. Often used interchangeably with “outdoor air”.

The periodic or continuous sampling and analysis of air pollutants in ambient air or from individual pollution sources.

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Explainers