At a sleepy council meeting in December, Paulsboro’s emergency-management coordinator waited his turn. Then, Glenn Roemmich stood, cleared his throat, and matter-of-factly suggested that the Gloucester County river town needed six-story warning sirens – “in case something happens” at the neighboring refinery.

But to warn of what?

It could be a small leak of hydrogen fluoride, like the one in October 2001 that caused a local school to rush its children and staff into the gym, and seal it with duct tape.

Or, it could be an unprecedented event – a mass release of this potentially lethal gas. In that case, for those closest to the plant, the siren might be a death knell.

The source of that danger could be the Valero Energy Corp. oil refinery that cleaves to Paulsboro, across the Delaware from Philadelphia International Airport. It is one of eight plants in the Philadelphia region that could put more than one million people at risk of serious injury or death in a “worst-case scenario,” according to the Environmental Protection Agency.

Across the country, there are at least 110 such facilities, though none has experienced a disaster resulting in widespread loss of life.

Industry representatives say that worst-case scenarios are highly unlikely and that the scenarios do not take safety mechanisms into account. Valero has used hydrogen fluoride since the 1940s without a major release.

But after the Sept. 11 attacks, the possibility of a deliberately engineered chemical catastrophe has raised alarms and calls for mandatory security measures.

No federal security standard exists for such companies, unlike for nuclear plants. Measures are largely voluntary and generally secret, with company officials saying they do not want to tip off terrorists.

Sen. Jon Corzine (D., N.J.) calls the absence of such federal regulations “Neanderthalic.”

“If we can’t deal with something as simple and straightforward a risk to the population as these chemical plants and refineries, I think we’re not taking homeland security seriously,” he said.

Valero’s worst-case scenario, on file at the EPA, involves a toxic release of 240,000 pounds of hydrogen-fluoride gas drifting 19 miles and exposing schools, hospitals and dense housing before it dissipates.

“Originally, when companies had to release worst-case scenarios, they said: ‘You don’t have to worry about this,’ ” said Sanford Lewis, a Boston environmental lawyer and author of a manual for community groups seeking to reduce the risk of chemical-plant hazards. “You can’t say that anymore. We all know there are people of ill will who want to see a worst-case scenario happen.”

In February, the FBI warned that al-Qaeda operatives “may attempt to launch conventional attacks against the U.S. nuclear/chemical-industrial infrastructure to cause contamination, disruption and terror.”

The devastation of such a toxic-gas release became apparent in 1984, when a cloud of methyl isocyanate from a Union Carbide pesticide plant in Bhopal, India, killed nearly 4,000 and injured 200,000.

A day before the United States went to war with Iraq, the General Accounting Office, Congress’ investigative arm, warned that although some chemical facilities were shoring up security, the extent of their preparedness was unknown. The GAO urged laws to create security standards.

That same day, Homeland Security Secretary Tom Ridge increased Coast Guard patrols for petroleum and chemical plants.

However, many communities are not aware of the hazards in their backyards.

On the East Coast, the Philadelphia region has the highest concentration of facilities that could endanger more than a million people. Four are in Gloucester County. There is one each in Salem and Delaware Counties. Two are in Philadelphia.

More than four million people – or 86 percent of the population of the eight-county region – could be exposed.

This month the debate over chemical-plant security flared on Capitol Hill. On one side is Corzine, whose bill would direct the Department of Homeland Security and the EPA to identify “high-priority” facilities and compel them to fix security weaknesses and study ways to reduce or eliminate chemical hazards.

Alternative legislation being developed by the Bush administration would impose security standards but not require consideration of safer technologies.

Corzine predicts the Republican-sponsored bill will be “100 percent on the side of the chemical industry.”

After the GAO report, the American Chemistry Council, a trade association of 200 companies that helped defeat Corzine’s bill last year, said that it supported a “national program” to make sure chemical plants assessed their vulnerabilities and addressed deficiencies.

A federal study of security at more than two dozen chemical plants in 1999 found measures at those plants ranged “from fair to very poor.”

The eight Philadelphia-area plants, which were not a part of the study, say they have strengthened their security since Sept. 11, but – for security reasons – they provided few details.

Valero’s spokeswoman Claire Riggs said the company’s perimeter, enclosed by a chain-link fence, was monitored 24 hours a day by cameras and multiple roving and stationary guards.

Some facilities are working with the chemistry council’s voluntary security guidelines.

“Our industry has spent a tremendous amount of sweat, tears, energy and creativity on addressing security since Sept. 11 and before Sept. 11,” said Dorothy Kellogg, plant-operations team leader for the council.

A New Jersey task force is working with the council to upgrade plants’ security. State Department of Environmental Protection Commissioner Bradley Campbell said that “a great deal of progress” had been made, but he would not elaborate.

“I think 9/11 was a loud wake-up call,” said Hal Bozarth, executive director of the Chemistry Council of New Jersey, representing 100 firms. “Right away, we all knew the business of chemistry was going to be vulnerable, and that extraordinary measures had to be taken, and I believe that in the vast majority of cases, they have been taken.”

Bozarth said that the security measures included cameras, concrete blocks, and stricter background checks.

The Philadelphia Police Department has offered non-mandatory security tips to city plants.

“The plants are all very different, and obviously there isn’t much in the way of standards,” said Ronald Koopman, who runs the “chem/bio” security program at the Lawrence Livermore National Laboratory in California.

Koopman said that some plants are better than others. Two refineries that he visited in the western and southern United States had “zigzag concrete barriers, they had borrowed armored personnel carriers, they had armed guards. They had a fence and tank-stopping concrete blocks.”

But citizen and labor groups say that security at many facilities remains inadequate.

“Most security precautions to date have been superficial,” said Rick Engler, executive director of the New Jersey Work Environment Council, representing 60 unions and environmental groups. “In this new era of relatively sophisticated terrorism, much more needs to be done.”

The Clean Air Act amendments of 1990 directed companies to submit risk-management plans – their worst-case scenarios, accident histories, and prevention and emergency-response programs. The plans, first filed in 1999, must be updated every five years.

The million or more people at risk in each of the eight plants’ scenarios include everyone living within a radius of a facility, or what the EPA calls the “vulnerable zone.” But a toxic plume would only affect those downwind of a release.

Still, thousands or tens of thousands could be exposed.

Among the region’s eight plants is Repauno Products LLC, in Gibbstown, Gloucester County, a specialty chemical maker that stores sulfur dioxide. Sulfur dioxide’s vapor can cause severe shortness of breath and suffocation.

Four other facilities use large quantities of chlorine – Solvay Solexis and FERRO in Gloucester County, DuPont Chambers Works in Salem County, and the Northeast Water Pollution Control Plant in Philadelphia.

Employed by Germany as a chemical weapon in World War I, chlorine gas can trigger chest pain, vomiting and, in high concentrations, suffocation.

The Northeast plant will soon discontinue the use of chlorine.

The other three – Valero, the Sunoco plant in South Philadelphia, and Conoco Phillips in Trainer, Delaware County – are oil refineries storing what the EPA calls “one of the strongest acids known.”

Hydrogen fluoride is used by 50 refineries in the United States to make high-octane gas, while sulfuric acid – also dangerous, but less likely to form a lethal cloud – is employed by 45 refineries.

Valero’s Paulsboro plant is the only refinery in New Jersey using hydrogen fluoride. Unlike a sister plant near Los Angeles, it has no plans to switch to a safer form of the chemical.

Hydrogen fluoride can become a colorless, ground-hugging cloud that can defoliate trees, scorch grass and etch glass. It may also burn eyes and skin, and, in dense concentration, flood lungs with fluid, causing suffocation.

“Hydrogen fluoride is really nasty,” said Jonathan Ward, director of toxicology at a University of Texas medical branch. “There are a lot of things that, if released, might smell bad, or there might be some chronic effects to be worried about, but you’re not going to kill people on the spot. Hydrogen fluoride could do that.”

The chemical is also a known quantity to some terrorists, said Neil Livingstone, board chairman of Global Options, a security firm in Washington. “Many terrorists come from oil-producing countries. Normally, people gravitate to stuff they know about, and [hydrogen fluoride] is something they know well.”

The vulnerable zones for the Valero, Sunoco and Conoco Phillips refineries overlap across the Delaware River, encompassing Philadelphia International Airport, the new sports stadiums, and many city neighborhoods.

In 1986, tests conducted by Lawrence Livermore and Amoco Oil Co. in the Nevada desert revealed the dangers of the concentrated kind of hydrogen fluoride used by refineries. In one test, potentially lethal levels from a 977-gallon release were detected five miles downwind.

There have been significant accidental releases elsewhere.

In October 1987, a crane operator at Marathon Oil’s Texas City refinery dropped a 30-ton heater on a tank, releasing 30,000 pounds of hydrogen fluoride. About 3,000 residents were evacuated, and 900 were treated for ailments ranging from eye irritation to long-term breathing problems.

“There were houses right up against the fence,” said Koopman, of Lawrence Livermore. “The only thing that saved people was that the [hydrogen-fluoride] plume shot 200 feet up in the air, and it went about 900 meters downwind before it actually came down into the neighborhood. If it had squirted out sideways, it would have killed hundreds, if not thousands.”

A month later, a Mobil refinery explosion in Torrance, Calif., caused a 100-pound leak of hydrogen fluoride. Six workers were hurt in the explosion.

In 1991, two workers died and five were injured after an accidental release at Southwestern Refining Co. in Texas.

In this area, there have been small hydrogen-fluoride leaks.

Between 1995 and 1997, four one-pound releases at the Sunoco refinery injured one worker in each accident.

In 1997, seven pounds of hydrogen fluoride escaped from the Trainer refinery, injuring two workers.

In Paulsboro, there have been two minor hydrogen-fluoride releases since Valero acquired the refinery in 1998.

The three refineries said that hydrogen fluoride did not travel off-site in any of the releases and that their facilities had numerous safety mechanisms, including leak detectors, a “water curtain” to remove vapors from the air, and a “rapid acid evacuation system” to transfer leaking acid into an alternate tank.

On Oct. 2, 2001, when 150 pounds of hydrogen fluoride leaked within the Valero refinery, the wind was blowing toward neighboring Greenwich Township, recalled the township’s emergency-management coordinator, Al Silbaugh.

Broad Street Elementary School ushered all the children and staff into the gym, and sealed the doors and windows with duct tape and plastic.

A major release with a higher concentration of the chemical, Silbaugh said, “could have been a real catastrophe.”

Glenn Roemmich, a police dispatcher, is responsible for protecting Paulsboro from disasters such as floods and earthquakes. As the volunteer emergency-management coordinator – a position with a $1,500 yearly budget – he also supervises evacuation and sheltering procedures in the event of chemical releases.

Roemmich, with Silbaugh, is trying to raise $112,000 for a system of five sirens, because right now, “there is no way to notify people except going door-to-door.”

Valero spokeswoman Riggs said the company “is committed to supporting” a siren system. But Silbaugh said he had yet to receive any commitment from area companies to help fund it.

In South Philadelphia, a community group and the city sued Sunoco for such improvements. A 1997 settlement required Sunoco to spend an estimated $5 million in upgrades and provide additional funds to build 10 warning sirens.

The 1986 Emergency Planning and Community Right to Know Act, passed after the Bhopal tragedy, set up local emergency-planning committees to prepare for such a catastrophe. But many are hamstrung by a lack of resources.

Despite community efforts in Paulsboro to educate the public about emergency procedures, the refinery’s risks remain a mystery to many residents.

Among a dozen interviewed in recent months, only one, a volunteer firefighter, was aware of Valero’s worst-case scenario or emergency precautions.

“Both industry and government have a duty to warn people if they could be put in harm’s way from chemical releases,” said Paul Orum, director of the nonprofit Working Group on Community Right-To-Know in Washington.

Also required of the companies by the Clean Air Act amendments was a public meeting to discuss their risk-management plans. In 1999, Valero and two other companies hosted an open house at the Gibbstown firehouse. The event drew fewer than 10 people, recalled a Repauno Products plant manager.

The companies also included some information on their plans in a newsletter mailed out by a community advisory panel.

The panel, composed of community members and representatives of five companies, has publicized the concept of “shelter-in-place,” which involves closing doors and windows, shutting vents, and sealing a room with duct tape and plastic.

The panel’s efforts include a coloring book featuring Shelly the Turtle. “Shelly stays safe when she shelters in her shell,” the book explains. Children can connect numbered dots that form a toxic-gas cloud.

Paulsboro Mayor John Burzichelli said shelter-in-place, not evacuation, may be the town’s only option.

“If you’ve ever tried to drive at 3:30 [p.m.] on our highways, you’ll never get anywhere,” he said.

But John Sorensen, a researcher at Oak Ridge National Laboratory in Tennessee, explained that “sheltering-in-place is not a simple, one-size-fits-all solution.”

A study by Sorensen found housing built before 1950 “will likely be unsuitable for sheltering without weatherization.” In Paulsboro, 38 percent of the homes went up before 1940.

For those living at the edge of a plant, there may not be time to shelter in place.

These people fall into what Stuart Greenberg, director of the nonprofit Environmental Health Watch, dubbed “the sacrifice zone.”

“It’s the area into which a cloud of dangerous concentration could move so fast that people will not be able to take protective action,” he said.

In city neighborhoods near Sunoco, “the closest people to the refinery don’t have a chance,” said Joanne Rossi, head of the Community/Labor Refinery Tracking Committee in South Philadelphia. “We’re dead if anything happens. The [hydrogen fluoride] is something the government itself needs to take a position on. The chemical is just too hazardous for the city.”

* Contact staff writer Adam Fifield at 856-779-3917 or Inquirer staff writers Mark Fazlollah and Jennifer Lin contributed to this article.