Sensors in Subway Passenger Areas Urged : Health: Congressman and others call for detectors after disclosure of potentially dangerous gases in Red Line stations. Such devices were first recommended in 1986.

Gas detectors should be installed within passenger areas of the Los Angeles subway to provide the level of safety recommended at the outset of construction, said local transit officials, a medical specialist and a member of Congress on Monday.

The comments came in response to a Times report Monday that methane and hydrogen sulfide gases are regularly entering the 15-month-old subway.

A committee of safety experts recommended in 1986 that sensors be placed inside the stations at the passenger platform level to help monitor hydrogen sulfide, a toxic gas that is heavier than air. But the subway was built with the sensors inside exhaust ducts, almost at street level.

Dr. Kaye H. Kilburn, a professor of internal medicine at USC who specializes in researching the effects of exposure to hydrogen sulfide, said Monday that sensors should be installed in the passenger areas.

“It’s far better that it show up on the (gas) probe than to have somebody hospitalized,” Kilburn said. “It doesn’t look like a very complex issue to me.”

A spokesman for the Metropolitan Transportation Authority reiterated Monday that emergency fans disperse both hydrogen sulfide and methane before the gases reach dangerous concentrations. Technicians with the MTA have said that they do not believe gas detectors are needed within the stations because trains mix the air, allowing the detectors in the exhaust ducts to monitor methane and hydrogen sulfide.

Franklin E. White, the agency’s chief executive, said he has asked his staff to further study the matter.

“Passenger areas of the stations normally are not the areas in which our engineers would expect any gas buildup because of the ventilation caused by fans and trains,” White said. “I have asked, however, that our engineers take a look at the issue and report on it to the board of directors at its June (22) meeting.”

The Times reported Monday that elevated levels of methane, an odorless gas that is lighter than air, have reached the MTA’s warning or alarm levels more than 350 times during the past 15 months. The warning and alarm levels are far below the concentration at which methane becomes explosive.

Hydrogen sulfide, which smells like rotten eggs, is present at as many as three of the subway stations. The gas has been detected at up to 9.9 parts per million, within the range in which health authorities say people exposed to it could suffer headaches, nausea or eye irritation. Hydrogen sulfide can be lethal at 150 p.p.m.

Kilburn said his studies of workers and residents around oil refineries have found that exposures of one to 10 p.p.m., in open-air environments, adversely affect balance and reaction time.

The gas has reached the MTA’s warning or alarm levels a handful of times and is most noticeable at the Civic Center station.

“There could be no possible reason not to have the sensors at the lowest possible points,” said Marvin L. Holen, an appointee to the MTA. Holen said he was skeptical of relying on train movements to adequately mix the gas.

“I’ve got to tell you, there’s a lot of wind in that (Civic Center) station,” Holen said. “And it smells awfully gassy to me.”

In Washington, Rep. Henry A. Waxman (D-Los Angeles) said the news of the gas incursions into the subway should prompt increased congressional oversight. In response to Waxman’s safety concerns nearly a decade ago, the subway project was modified to guard against a methane-gas explosion such as one that blew apart a Fairfax District clothing store.

Local transit officials designed the stations and tunnels with a lining of plastic to seal out gases. Congress, as a condition of providing nearly half the funding for the first segment of the $1.45-billion Red Line, outlawed tunneling on Wilshire Boulevard in the Fairfax area.

Eight years ago, the City Council responded to Waxman’s concerns by forming the panel of safety experts, who recommended that gas detectors be placed within passenger areas of the stations.

Now, Waxman said, “I think the disclosures that have come out (this week) with respect to the methane gas danger underscore the need for congressional oversight, by way of hearings or investigation.”

Waxman said that he would write to the chairmen of the House committees that control transportation spending. “I’m going to be looking at all the things Metro Rail is doing, to see that the promises are kept,” he said.

Noelia Rodriguez, spokeswoman for Mayor Richard Riordan, said that the mayor is concerned about the gas problems and has asked White to address the issue at Wednesday’s MTA meeting.

Nick Patsaouras, an appointee to the MTA who has criticized the quality of subway construction and inspection, called on White to place the gas detectors inside the stations.

“I don’t see why we should not do it,” said Patsaouras, who is an engineer. “It cannot hurt, and it can help. I don’t care what it costs.”

The article Monday also reported problems with the installation of the plastic gas barrier.

County Supervisor Michael D. Antonovich, an MTA board member, said that officials had been “sold a snake-oil membrane” at a cost of $2 million per mile of tunnel. Antonovich called the installation part of a “pattern of neglectful oversight, mismanagement and disregard for standard industry practice.” He, too, called for installation of gas detectors within the stations.

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Contractors who installed the plastic lining said the material was difficult to handle. Some of them have said that its design was flawed.

Representatives of Parsons-Dillingham, the firm that supervised construction, have said they needed more inspectors for the first subway tunnels and stations. They have said they are doing a better job of supervising ongoing construction.