Los Angeles County health officials plan to ask a judge on Friday to once again modify the relocation program for Porter Ranch residents so Southern California Gas Co. can pay to professionally clean all their homes of dust particles found to contain some contaminants.

The announcement came during a public meeting Thursday night held by the Department of Public Health to assure Porter Ranch residents that while the results of indoor testing showed that metal contaminants consistent with the nearby Aliso Canyon gas leak were present in surface dust in several of their homes, the levels were low. No long term health effects are expected, said Dr. Jeffrey Gunzenhauser, interim director for the Los Angeles County Department of Public Health. But he said he wanted residents to have their homes cleaned professionally, then inspected again, before they return.

“We don’t recommend you do the cleaning yourself,” he told the crowd of about 150 residents who attended the meeting at Porter Ranch Community School. “We want you to go to someone who is certified to follow the protocols we’ve established.”

Last week, the health department issued a directive to SoCalGas to foot the bill for cleaning homes within a five-mile radius from the Aliso Canyon storage field, where natural gas began spewing from one of 115 aged wells there in October. The leak sent tens of thousands of metric tons of methane in the air and leak become known as the largest event of its kind in the nation. SoCalGas, which operates the storage facility, has asked a court to throw out the health department’s directive.

Health officials called the event unprecedented. There were reports of headaches, nosebleeds and vomiting during the leak, and at least 6,000 residents relocated. But even after the leak was controlled on Feb. 11 and capped on Feb. 18, health complaints continued from residents who moved back. Some residents refuse to return until they are certain there are no health risks. Relocated residents have been told they have until May 31 to move back.

Gunzenhauser said there was nothing in the test results that concerned him, but he said he understood why residents may feel uneasy. There are no prior long term health studies on the effects of that much methane exposure or how the metals such as barium, manganese, vanadium, aluminum and iron interact.

“Everyone has concerns about health effects,” he said. “That’s understandable.”

The health department will try every effort to make SoCalGas comply with the clean-up order, Gunzenhauser said.

“We do remain commmited to this community,” he added.