40,000 residents under evacuation orders in Southern California as tank containing toxic chemical at risk of explosion

(CNN) — Approximately 40,000 residents in Orange County, California, are under evacuation orders as authorities are concerned a tank filled with a toxic chemical will either leak or explode.

Authorities have spent the past two days trying to prevent the tank, which is full of the chemical methyl methacrylate, from exploding after it began to overheat. Evacuation orders were issued to those in the 9-square-mile area around the facility involved, impacting over 40,000 residents.

The chemical, also known as MMA, is used to manufacture plastics and can potentially cause respiratory issues if humans are exposed, according to the Environmental Protection Agency.

The temperature of the tank is continuing to decrease, Orange County Fire Authority Division Chief and Unified Incident Commander Craig Covey said in an update Friday evening.

“It’s down to a temperature around 61 degrees, with 50 being its happy place,” Covey said, adding that officials are working overnight to prevent the tank from exploding or leaking.

The tank cooling down is “giving us opportunity to reconsider engaging in close proximity to implement some of the concepts that were outside the box,” Covey added.

On Friday, police made a reverse 911 call to tell people to evacuate and posted on social media about the evacuations, Garden Grove Police Chief Amir El-Farra said. About 15% of people — or about 6,000 residents — from the evacuation area had refused to leave, he said. Thirteen schools and two facilities within the Garden Grove Unified School District were also evacuated Friday morning.

The industrial site where the tank is located is about 5 miles from Disneyland and about 4 miles from Knott’s Berry Theme Park.

MMA is heavier than air, Covey said at a news conference Friday, and the air should be safe outside of the evacuation zone, Orange County Health Officer Dr. Regina Chinsio-Kwong said in a later update.

“This is going to happen unless some brilliant guy behind me here figures out how we can mitigate this incident,” Covey said as he emphasized the need to evacuate. “This thing is going to fail.”

Exposure to MMA can cause major respiratory issues, including “significant irritation” to the lungs and nasal passages, as well as dizziness and nausea, Chinsio-Kwong said. There are not many documented cases of human interaction, so it is unpredictable what the effects of a potential explosion could be on the population, she said, encouraging people to stay out of the evacuation zone for that reason.

“We’re going into unique times and we have limited information,” Chinsio-Kwong said.

The chemical, which is not currently detected in the air, can produce a fruit-like scent, although smelling it doesn’t mean you’ve gotten enough exposure to have symptoms, she said in another update.

Authorities initially responded to a vapor release from the tank containing MMA at the Garden Grove facility on Thursday, Orange County Fire Authority Interim Fire Chief TJ McGovern said Friday. One of the three tanks at the site had increased in temperature and activated a relief valve and overhead sprinklers to try to cool the tank, he said. The other two tanks have either been neutralized with a chemical agent or aren’t at risk.

Evacuation orders were issued for the area Thursday, but they were lifted that night after the vapor conditions improved, McGovern said. As crews tried to remove and contain the product from the one tank, they realized the tank had a damaged valve so the chemical couldn’t be removed, which caused local authorities to reinstate the evacuation orders, he said.

“I was sleeping in my house until this morning when they told us we had to leave,” resident Diane Chavira told CNN affiliate KCAL/KCBS, forcing her to collect her four dogs and get out of the area.

“It’s been chaos,” Jacqueline Riegos, who evacuated from Stanton, told KCAL/KCBS. “Just dealing with everybody coming and going and nobody knows anything. Nobody can really give us any details about what’s going on. … And we don’t know how long this is going to be.”

McGovern emphasized that there was no vapor coming out of the tank as of Friday, and authorities are continuing to monitor the air quality.

The manufacturer’s response team had tried everything they could but couldn’t mitigate the crisis, Covey said Friday. The only two options given to authorities were either the tank would crack and leak the 7,000 gallons of MMA into the surrounding parking lot, or the container would explode, he said. CNN has reached out to GKN Aerospace Transparency, the owner of the facility, for information on their efforts to manage the emergency.

“This is highly volatile, it’s highly toxic and it’s highly flammable,” Covey said.

Authorities warned that there were many factors that could contribute to the tank’s demise, which is why they expanded the evacuation orders to such a large area. “People need to get out of their houses and get into a safe space because when this thing goes, depending on the wind direction it’s going, we cannot control the weather,” Covey said.