PORTER RANCH (CBSLA.com) — Several dozen people demonstrated outside the Southern California Gas Co. Community Resource Center in Porter Ranch Friday demanding that the utility pay up-front costs for cleaning up the insides of their homes that are covered in oily residue.

Vilma Paylan said she is hiring a cleaning company out of her own pocket to scrub her home before they move back in. “All the cushions, all the chairs, everything to the ceiling” are covered with brown spots, she said. “I haven’t received anything yet reimbursement-wise.”

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According to the utility, it has sent out $36 million in reimbursement checks.

SoCal Gas Spokesman Mike Mizrahi said paying for cleanings inside the homes is not necessary. “The public health department has said folks should air out their houses, open up their windows, open up their doors. There might be some other avenues where we can achieve the same purposes.”

On Friday, Los Angeles Councilman Mitch Englander wrote a letter to the company saying: “More than 150 experienced symptoms upon their return home after the capping. It is imperative SoCal Gas provide mobile clinics to affected areas.”

Gas Co. officials said Friday the company is offering exterior home-cleaning for people “who have reported brown spots they believe to be related to the leaking well.” According to the company, the spots have generally been reported on the exterior of homes, but the utility “will also assess reports of residue on surfaces inside homes.”

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“Sampling results reviewed by both a toxicologist and a medical expert suggest that the residue does not pose a health risk,” according to SoCal Gas. “However, we are providing cleaning services for residents or reimbursing residents who have already had the residue cleaned.”

The Aliso Canyon gas leak was first reported Oct. 23. SoCal Gas dug a relief well and cut off the flow Feb. 11. The well was formally declared sealed Feb. 18.

It spewed more than 100,000 tons of natural gas into the air, making it the largest methane leak in U.S. history, according to a study released by UC Davis and the National Oceanic and Atmospheric Administration.

The study found that the daily amount of methane leaked between Oct. 23 and Feb. 11 was enough to fill a balloon the size of the Rose Bowl.

Thousands of residents moved out of their Porter Ranch-area homes during the leak. Students at two Los Angeles Unified School District schools were relocated to other campuses.

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Residents living in temporary housing funded by the Gas Co. have until March 18 to return to their homes under a court order that was upheld this week by a state appeals court.