A smell sickened L.A. County residents for months. Officials say a fire that torched wellness products is to blame.

Panoramic view of Los Angeles skyline at sunset, California, USA (Getty Images)

In early October, Monique Alvarez and her family noticed an acrid, rotten-egg smell had invaded her Carson, Calif., home in Los Angeles County. Soon, they started experiencing headaches and stomach pain.

"The smell itself was never a huge issue to me," Alvarez, 40, told The Washington Post. "It was more so waking up feeling like I left my [stove] gas on."

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Her breaking point came two weeks later, when Alvarez said she found her 3-year-old daughter lying on the floor, saying, "I have an owie in my body."

Distressed, the lifelong Carson resident left town with her husband and three children. They were not alone.

More than 4,600 complaints have been filed about the smell since it was first reported on Oct. 3, according to the Los Angeles Times. Some 3,200 residents in Carson and surrounding cities were forced to temporarily relocate to hotel rooms paid for by the county, and those who stayed home were given air purifiers. Alvarez and her family were among the residents who took a hotel room.

For close to two months, investigators puzzled over why the noxious gas was overwhelming the Carson area. Officials knew the stench was the product of a colorless and odorous gas called hydrogen sulfide produced by decaying organic material - and that it was probably emanating from the Dominguez Channel that runs through Carson, the Times reported. But they could not identify what had changed conditions in the channel.

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"There had to be, to put it in plain language, something out of the water that we normally don't see," Mark Pestrella, the L.A. County Public Works director, told the Times.

On Friday, the South Coast Air Quality Management District, an agency that oversees the area's air conditions, announced that its investigation had pinpointed a culprit: A three-alarm fire that erupted on Sept. 30 at a Carson warehouse storing wellness and beauty products.

After the fire was extinguished - an effort that took days - the chemicals contained in the products, including ethanol, flowed into the sewer system and into the Dominguez Channel, the management district said in a news release. The chemicals caused organic material in the channel to decay and release abnormally high hydrogen sulfide levels.

At its worst, the hydrogen sulfide levels in the air reached nearly 7,000 parts per billion - 230 times higher than the state's nuisance standard, the management district said.

Pestrella told the New York Times that the warehouse stored "large vats of ethanol." An L.A. County fire inspector told KTLA that the blaze spread among rubbing alcohol wipes stored in crates. And a class-action lawsuit filed by affected residents alleges that the warehouse was stacked high with boxes of ethanol-based hand sanitizer. In the days after the fire, the suit adds, "large amounts of soggy, charred debris" - including the sanitizer - remained piled at the warehouse.

As a result of its investigation, the management district issued violations to four companies, as well as L.A. County, for their roles in contaminating the air. Virgin Scent, doing business as Art Naturals, and Day to Day Imports had stored "large quantities" of wellness and beauty products in the warehouse, the agency said. The warehouse is owned by Liberty Properties Limited Partnership and its parent company, Prologis. Los Angeles County manages the channel.

None of the companies immediately returned a request for comment from The Post late Sunday, nor did a spokesperson for L.A. County. A Prologis spokeswoman told the L.A. Times that the company was working with the L.A. County Fire Department to clean the property and prevent further chemical runoff.

As of last week, L.A. County has spent $54 million on cleaning up the channel, as well as paying for hotel rooms and air purifiers, the Los Angeles Times reported. If the cleanup continues until March, those costs could reach $143 million.

"The gas has caused and is continuing to cause physical injury to residents and is interfering with [their] ability to use and enjoy their properties," states the class-action lawsuit, filed on Nov. 12 in Los Angeles Superior Court. It adds: "The full extent of exposure is unknown."

Alvarez, who is a plaintiff in the lawsuit, said that since she and her family returned home on Nov. 26, the odor has dissipated, but they are still experiencing symptoms.

Alvarez explained that she has deep roots in Carson: Her grandfather worked there as a farmer as a young boy, and her parents raised her there. "It's nice to be home - but . . . I'm really considering relocation," she said. "I don't feel like home is a safe place."

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