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GAVIN NEWSOM
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General Public
Information on Methyl Methacrylate (MMA)
5/23/2026



Last ​Updated: June 05, 2026, 5:15​​ p.m. PDT​

Current Situation​

  • The Orange County Fire Authority announced Tuesday evening (May 26) that there is no longer a threat of explosion, fire or chemical leak for a damaged tank at the GKN Aerospace facility in Garden Grove. 
  • All evacuation orders have been lifted.
  • Local, state, and federal partners continue to monitor air and water samples to confirm there have not been leaks that may affect the public's health.
  • Updates and additional FAQs about MMA and questions about any potential health impacts will be continuously added to this webpage.

Translated Materials

What Happened in Orange County?

On May 22, 2026, an evacuation order was issued to several cities because of the potential release of methyl methacrylate (MMA) from a damaged tank at a local business. The health and safety risk has been eliminated and this evacuation order was fully lifted on May 26, 2026.   



Returning Home After the Evacuation

What should I do when re-entering my house/business/school after this evacuation? 

MMA is not expected to be in homes, businesses, schools, or other buil​dings in the area that was evacuated. At this time, everyone in the area can return to their normal activities. 

After an evacuation from ANY incident relating to potential hazardous material, when you return, consider the following best practices: ​​

  • Continue to monitor any notifications from the City of Garden Grove and Orang​​e County incident information resources. 
  • Air out the home.  
    • Normal household odors after being away include garbage smell, refrigerator odor, spoiled food, or mustiness. If you notice any household smells or mustiness, open windows and doors for a short period. If you have an HVAC, you can also run the fan to circulate air.
  • Take action if something seems wrong.  

    • ​Contact the local health department for guidance, if you think you smell unusual odors.

    • If you are experiencing symptoms and need to speak to an expert about how to proceed, you can call the California Poison Control System at 1-800-222-1222. If you are having a medical emergency call 911.

Is it safe to eat food left in my home during the evacuation? 

Food inside the home is not expected to be affected. Use normal food safety precautions after being away from home. Throw away perishable foods if the refrigerator or freezer lost power or if food is warm, spoiled, moldy, or has an unusual odor. Do not taste food to decide if it is safe. When in doubt, throw it out. 

What about produce from backyard gardens? 

Backyard produce is not expected to be affected. Wash fruits and vegetables with clean water before eating, as usual. 

Should I clean outdoor surfaces, patios, cars, or play structures before using them again? 

No special cleaning is recommended as outdoor surfaces are not expected to be affected. After being away, typical dirt or dust may have accumulated so you may want to first rinse or wipe surfaces as you normally would before resuming use. ​​​

Did this incident damage homes, cars, patios, outdoor furniture, or other property? 

This incident is not expected to have caused damage to homes or property. After being away, you should always conduct a visual inspection.  

Is the drinking water supply safe?  

Water supply and quality in areas in and near the previous evacuation zone remain safe and reliable. The Orange County Groundwater Basin has not been impacted by the recent chemical incident in Garden Grove. Visit Garden Grove Hazmat - Orange County Water District for more information. ​

​Air Quality Monitoring​

What is being done to make sure the air is safe? 

Air monitoring equipment has been placed along the site perimeter (fenceline) and in nearby communities to continuously measure air quality. Monitoring has been maintained throughout the transition from the incident response phase to the recovery phase. During the cleanup process, air monitoring will be conducted at the fence line and in the community under the oversight of South Coast Air Quality Management District (AQMD).

Is the air safe? 

Air monitoring, including for volatile organic compounds (VOCs) such as MMA, was conducted May 22–27 and air monitoring data was reviewed by the Office of Environmental Health Hazard Assessment (OEHHA). OEHHA confirmed that the concentrations of VOCs in the area were similar to normal background. Based on this data, there is no risk to the public from MMA exposure from this incident. ​

Health Effects and Exposure

How Do I Know If I Have Been Exposed To MMA?

There is no risk to the public from MMA exposure from this incident. MMA is not expected to be in homes, businesses, schools, or other buildings in the area that was evacuated.

What are the short-term health effects of exposure to MMA? 

Exposure to methyl methacrylate (MMA) can cause short-term symptoms including burning or watery eyes, nose or throat irritation, coughing, wheezing, chest tightness, shortness of breath, headache, dizziness, lightheadedness, unusual sleepiness, nausea, or skin irritation. These are quickly reversible with fresh air. Health impacts usually occur only if someone was in direct contact with MMA, for example, an accidental spill for someone working with MMA.

What symptoms should I watch for after being near the evacuation zone? 

MMA is not expected to be in homes, businesses, schools, or other buildings in the area that was evacuated. However, take note if you smell an unusual sharp fruity odor and have any of the following symptoms: 

  • Burning, watery, or irritated eyes 

  • Nose or throat irritation 

  • Coughing, wheezing, chest tightness, or shortness of breath 

  • Headache, dizziness, lightheadedness, unusual sleepiness, or nausea 

  • Skin redness, itching, burning, or irritation 

If you think you smell any unusual odors, are experiencing symptoms and need to speak to an expert about what to do, call the California Poison Control System at 1-800-222-1222. ​

If I have asthma or another respiratory condition, is there anything special I should do?

People with asthma, COPD, heart or lung disease, or other respiratory conditions may be more sensitive to various irritating odors, smoke, dust, stress, or changes in air quality. Follow your provider’s usual advice to manage your condition, which might include regular medications and having a rescue inhaler with you. 

Is there any possibility of long-term health effects from the types of MMA exposure that might occur during an incident like this? 

MMA is not expected to be in homes, businesses, schools, or other buildings in the area that was evacuated.  Long-term health effects from MMA exposure have been reported in people who worked with MMA and who were exposed to repeat or prolonged high concentrations of MMA over long periods of time. While no long-term health effects are anticipated in the community as a result of this incident, some short-term or “acute” exposures to the skin or from breathing in MMA vapor may in rare cases cause sensitization or allergic reactions, which can lead to long-term health effects; in these rare cases, typically high levels of exposure occurred. Pregnant people who believe they were exposed should seek medical guidance, as there is some evidence that MMA can affect a developing fetus.  

About Methyl Methacrylate (MMA)

What Is Methyl Methacrylate (MMA)?​

Methyl methacrylate (MMA) is a clear, highly reactive chemical that is used to manufacture a range of acrylic materials including Plexiglass, as well as some coatings, resins, and adhesives. It is also used to make some acrylic nail products, dental materials, and bone cement for orthopedic procedures.  

MMA in its liquid or vapor form is flammable and toxic at high concentrations. MMA is described as having an acrid, fruity odor. MMA can be smelled at concentrations far below those that can harm your health. MMA is generally stored in special enclosed containers or tanks to limit vapor generation and explosion risk.  

Liquid MMA quickly evaporates to gas. MMA can also evaporate from the soil or water when it is exposed to air. MMA breaks down quickly in air or water, typically in hours.

How Is Methyl Methacrylate (MMA) Used?

MMA is widely used to manufacture a range of shatter-resistant acrylic materials such as Plexiglas, as well as a variety of resins coatings, and adhesives. MMA is also used by dentists to make dental materials such as crowns and fillings as well as by surgeons to make bone cement for some orthopedic procedures.  ​