A study published Thursday confirmed that the 100,000 tons of methane that flowed out of Aliso Canyon was the largest natural gas leak disaster to be recorded in the United States, and that it doubled the methane emission rate of the entire Los Angeles basin.

Researchers with the UC Irvine and Davis campuses, along with the National Oceanic & Atmospheric Administration found during the peak of the leak that “enough methane poured into the air every day to fill a balloon the size of the Rose Bowl.”

University officials called it a first-of-its kind study on the gas leak, published in the journal Science.

“The methane releases were extraordinarily high, the highest we’ve seen,” said UC Irvine atmospheric chemist Donald Blake in a statement. Blake, who has measured air pollutants worldwide for more than 30 years, collected surface air samples near homes in Porter Ranch.

Results from the samples showed that there were above-normal levels of several compounds that are found in natural gas, including benzene, toluene and xylenes.

“Some of the volatile organic compounds have been linked to health effects if exposure is long-term,” Blake said.

The environment also will be affected, researchers said.

“Our results show how failures of natural gas infrastructure can significantly impact greenhouse gas control efforts,” Tom Ryerson, a lead scientist with NOAA, said in a statement.

Using a specially equipped Mooney aircraft, scientist Stephen Conley of Scientific Aviation and UC Davis conducted seven flights over the area in early November to measure methane and other chemicals in the area around Aliso Canyon, the site of the breached Southern California Gas Co. well.

Conley said his readings were so high throughout the San Fernando Valley, that he thought his gear was broken.

“It became obvious that there wasn’t anything wrong with the instruments,” he said in a statement by the university. “This was just a huge event.”

Researchers said the rate of methane emissions created “the largest known human-caused point source of methane in the U.S., twice the size of the next-largest source, an Alabama coal mine.”

In a statement, SoCalGas officials said they could not confirm the scientists’ conclusion that 100,000 tons of methane was released into the air, but said their company will examine calculations by such agencies as the California Air Resources Board to produce what they say is a more accurate measurement.

“It is important to note that experts agree there are no long-term health effects associated with this event,” according to the statement. “However, methane is a greenhouse gas, and it is important to put the amount of methane released, as it relates to greenhouse gas emissions, into context.”

Natural gas began leaking from one of the 115 aged wells on Oct. 23. One day later residents began calling in complaints to the South Coast Air Quality Management District. There were reports of headaches, nosebleeds and vomiting. Since then, there have been 6,000 residents who relocated. Two local elementary schools were affected, with nearly 2,000 schoolchildren and staff moved to other schools. Gov. Jerry Brown declared a state of emergency on Jan. 6.

Lawmakers on local, state, and federal levels learned that regulation over the Aliso Canyon storage facility and the wells had been lax and no contingency plans for such breaches or other disasters were in place. As a result, a pile of legislation has been introduced to strengthen the way natural gas is produced, processed and transferred nationwide.

In addition, lawsuits have been filed against SoCalGas by Los Angeles officials and by residents who said the leak has caused them illness, lost time at work and other inconveniences. One family has filed a wrongful death lawsuit against SoCalGas, alleging the natural gas leak hastened the death of a woman who was ill with cancer.

The leak lasted for 118 days until it was controlled on Feb. 11.

Scientists with the universities and agencies involved in the study said their research shows the value of quick airborne sampling soon after such chemical releases. Their work was funded by the California Energy Commission, the Southern California Gas Co., the California Agricultural Experiment Station and NOAA.

They hope their work will help officials assess public health risks.

“If we don’t measure these things quickly, we won’t have any idea what kind of response might be called for,” Conley said. “We’re happy that we could provide state officials with the scientific information they needed.”