When an invisible, odorless, lethal gas seeped from a faulty water heater and spread through a Roanoke College dormitory early one summer morning, there were no alarms to rouse the sleeping victims.

Five months later, it remains unclear whether the carbon monoxide poisoning -- which left one person dead and dozens ill -- will become the kind of statewide alarm that leads to legislation.

A Southside Virginia legislator says he plans to introduce a bill next month that would require carbon monoxide detectors in all newly constructed buildings. It will be the second such attempt in as many years by Sen. Frank Ruff, R-Mecklenburg County.

At its winter session a year ago, the General Assembly delayed action on Ruff's bill and asked for guidance from the Virginia Housing Commission. The commission opted not to endorse the legislation after a nearly yearlong study. Concern about the reliability of commercially available carbon monoxide detectors was one factor in the panel's decision.

Still, Ruff hopes the Roanoke College incident in July will raise awareness about the risks of carbon monoxide, which according to the Centers for Disease Control and Prevention is the leading cause of accidental poisoning deaths in the country.

"As we learn more about what the dangers are in our society, we have a responsibility to look at them and make decisions about whether there is a public need for the government to get involved," Ruff said.

Ruff said he intends to let his bill from last year die. That proposal (SB 667) would have required that certain rental units -- those with fuel-burning appliances, an attached garage or carport, or a location next to a parking space -- be equipped with carbon monoxide alarms as part of the state's Landlord-Tenant Act.

This time around, Ruff said he will submit a new bill mandating the devices as part of the building code for all new residential and commercial structures. Buildings that have fuel-burning appliances such as gas furnaces and water heaters are the most prone to carbon monoxide leaks. But because the gas also can leak from portable devices such as generators, or find its way inside a home from outside sources such as automobiles, no building is totally safe.

Ruff said he expects some opposition to his bill, in part because of the cost. Carbon monoxide detectors usually sell for $20 to $60 in most hardware and department stores. But the costs are coming down, Ruff said, and his bill will likely call for a gradual installation schedule for existing buildings.

"We'll try to phase it in so it won't be too much of a sticker shock," he said.

Ruff's bill has the support of the Virginia State Firefighter's Association, which had been considering the issue before the Roanoke College accident. "I think that incident will carry a lot of weight with the legislators," said Charles Singleton, chairman of the association's legislative committee.

At least 11 states have passed laws in recent years requiring carbon monoxide alarms to some degree, according to the National Conference of State Legislatures, and even more cities and counties have adopted their own ordinances.

But the International Code Council, which adopts model building codes followed by most cities, counties and states, has yet to see a need for mandating the detectors, in part because of concerns about their reliability.

Several studies, including a 2004 research project by the Gas Technology Institute, have found problems with the alarms on both ends of the spectrum -- some of the devices issue false alarms, and others remain silent when exposed to dangerous levels of carbon monoxide.

Alarm manufacturers say the tests involved older models, and that advances in technology have corrected many of the problems.

A year ago, Ruff introduced his bill at the request of a constituent who became ill from carbon monoxide fumes generated by a heated swimming pool at a vacation home. This year, he has a much more serious scenario to cite in pushing for his bill.

On the morning of July 14, carbon monoxide from a water heater in the Sections dormitory at Roanoke College permeated the three-story building. Walter Vierling, a 91-year-old retired pastor from Giles County, died in the dorm room where he was staying as part of a church conference.

More than 100 other people staying in the dorm for summer programs became ill and were taken to local hospitals for treatment or observation.

An investigation by Salem authorities found that a gas-powered water heater in the dorm's basement malfunctioned and caused the carbon monoxide leak. A Florida attorney hired by some of the victims said in August that he plans to file a product liability lawsuit against the heater's manufacturer, but to date there has been no litigation.

As bad as the incident was, some legislators are wary of letting one worst-case scenario drive a statewide mandate for carbon monoxide detectors.

"I think there's always the potential for overcorrecting, and you've got to make sure you're careful about it," said Del. William Fralin, R-Roanoke. Fralin said that while he's willing to consider Ruff's bill, he wonders if it's necessary to require the alarms in every new building.

Other Roanoke Valley legislators could not be reached last week.

Even without a law, Fralin said, high-profile incidents of carbon monoxide poisoning are likely to influence many homeowners and businesses to install carbon monoxide detectors on their own.

Roanoke College did just that, putting the alarms in every building on campus within weeks of the July 14 incident.

Less than a month later, a blocked chimney in a campus fraternity house caused carbon monoxide from a boiler system to leak into the house. Everyone in the house escaped safely, though. Because that time, the alarm sounded.