hazardous materials

The UC has completed its key operational objectives and has officially begun demobilization. Remaining action items will continue to be handled by the appropriate agencies through normal coordination. These follow up tasks do not require an active UC structure, but they will still be reviewed and finalized to ensure they meet all necessary requirements. Therefore, effective 7/22, we will no longer publish daily or weekly updates regarding the activities of the Unified Command (UC)*.

Air monitoring for Volatile Organic Compounds (VOCs) and Methyl methacrylate (MMA) is being conducted at the facility perimeter and in the surrounding community under South Coast AQMD’s oversight. Monitoring includes stationary and mobile air monitoring equipment.

DETECTION LIMIT: A detection limit is the lowest level of a pollutant that a monitor can measure. If the level of VOCs or MMA in the air is below these limits, the reading is considered a non-detect.

The detection limit for VOCs is 0.1 parts per million (ppm) and the detection limit for MMA is less than 1 ppm for the air monitoring devices being used. 

ODOR THRESHOLD: MMA has a very low odor threshold (<0.7 ppm), meaning people may notice its distinctive fruity or plastic-like odor at concentrations well below levels associated with health concerns. Because the odor threshold for MMA is lower than the detection limit, some people may be able to smell MMA even when air monitoring results show non-detect levels. 

SHORT TERM HEALTH THRESHOLD: MMA has a short term (8-hour) health-based exposure level of 17 ppm, set by the U.S. Environmental Protection Agency.  Breathing air with MMA below this level is not expected to cause adverse health effects.

So far, air monitoring shows no elevated readings, and all data is within typical levels. 

General Terms 

*Unified Command (UC) is a structured approach to incident management that brings together the Incident Commanders of multiple agencies, jurisdictions, or organizations to coordinate a response while each retains its own legal authority, jurisdiction, and functional responsibilities. As of the operational period beginning 6/19/26, this UC includes the OC Health Care Agency and GKN Aerospace.

As of 7/22/26, key operational objectives of the Unified Command (UC) have been completed, with only work related to the “incident” tank (Tank #1) remaining. Tank #1 activity will continue to be completed in consultation with appropriate oversight agencies but does not require an active UC structure. Therefore, the UC is beginning demobilization to stand down the formal structure. 

*Inhibited or Neutralized MMA – When MMA is inhibited, it becomes far less likely to cause a chemical reaction. 

• The added stabilizer works like a “brake pedal,” preventing the MMA from breaking down or turning into something more dangerous.
• This makes the material much safer to handle, store, transport, and clean up.

Hazardous Material Disposal: California Department of Toxic Substances Control (DTSC) is the primary state regulatory agency for hazardous waste in California. For information visit https://dtsc.ca.gov/managing-hazardous-waste/.

Resources: 

Garden Grove Community Update | GKN Aerospace

City of Garden Grove Information Page: https://ggcity.org/hazmat-incident

County of Orange Information Page: https://www.ocgov.com/gkn-aerospace-hazmat-incident

For an easy-to-use search tool where you can look up environmental information for sites in Orange County —like hazardous chemicals inventory, inspection reports, hazardous waste, cleanup work, and contamination—visit https://siteportal.calepa.ca.gov/nsite/map/help.

EH is designated by the California Environmental Protection Agency (CalEPA) as the local Certified Unified Program Agency (CUPA) to implement and enforce hazardous waste and materials regulatory management programs in partnership with Participating Agencies that involve the local fire departments. The Participating Agencies include Huntington Beach Fire, Orange City Fire, Fountain Valley Fire, and Los Angeles County Fire for the city of La Habra.

EH also functions as a local agency to carry out the State’s CalRecycle Used Oil Recycling Program and Waste Tire Management Program, promoting the recycling of used motor oil and tires to prevent environmental contamination.

(714) 433-6000
1241 E. Dyer Road, Suite 120, Santa Ana, CA 92705
Environmental Health Office Hours:
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Cashier (Payment) Hours: 8 a.m. - 4 p.m.