Actively Monitoring Air Quality

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

May 27th - June 2nd

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

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

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.

Ascon’s air quality monitoring data has consistently shown air quality has been safely below health-protective screening levels, including during active work. Based on this data and while there is no active earthwork occurring onsite, DTSC has approved a pause in offsite monitoring and a modification in onsite monitoring.

  • Onsite Monitoring: Six air monitoring stations for dust and total VOC concentrations are located around the Site perimeter. Total dust and VOC concentrations are measured and reported weekly.
  • Offsite Monitoring: Offsite monitoring is currently paused but 2019-2023 results from five air monitoring trailers for dust and VOCs within the surrounding community are still available above. Offsite monitoring will resume with restart work.

Learn more about how Ascon conducted air monitoring during previous remedial fieldwork here, and learn more about air monitoring practices during 2019-2023 onsite activities 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 currently occurring at the following onsite perimeter locations:

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.

See Full Glossary

Explainers