Once again, what happened to a college community in Southwest Virginia could be the rallying cry for a state law requiring carbon monoxide detectors.

But there's no guarantee that change will come from Sunday's carbon monoxide leak at a Blacksburg apartment complex building, which poisoned 25 people.

After all, the General Assembly declined to pass a law requiring carbon monoxide detectors following a similar incident last summer at Roanoke College.

Although the Senate approved a bill earlier this year mandating the devices in college dormitories and assisted-living facilities, a House committee tabled the measure for a year to allow more study.

The Virginia Housing Commission, which was asked to examine the bill along with the state Board of Housing and Community Development, is scheduled to take up the matter Sept. 19.

Commission members are wrangling with two issues that have concerned some lawmakers: the relatively high cost of carbon monoxide detectors and questions about their reliability, said Emory Rodgers, deputy director of the state Department of Housing and Community Development.

"There is some caution about making something mandatory. Once you do that, you've taken a real serious step," Rodgers said. "And you want to make sure that if you make something mandatory ... there is some durability and dependability on how long it will last."

A 2002 study by the Gas Technology Institute found that six of 10 commercially available brands failed to detect potentially dangerous levels of carbon monoxide in some cases and issued false alarms in others.

Manufacturers have said the study involved older models and that technology has since improved.

But problems remain, including degradation of electrochemical sensors over time, said Jerry Weiss, executive director of the Carbon Monoxide Safety Association.

"It is a problem, there's no doubt about it, but something is better than nothing," Weiss said.

At least 11 states have laws that require carbon monoxide detectors to some degree, according to the National Conference of State Legislatures. Even more cities and counties have enacted similar requirements.

Unless there's a worst-case scenario involving deaths or mass illnesses, proposals in other states and localities are often short-lived, Weiss said.

"We hear about a particular story, we talk about it for two or three days, and then it's out of sight and out of mind," he said.

Carbon monoxide detectors generally sell for $25 to $60. While that may not be much for some homeowners -- about 30 percent of U.S. homes have the devices, the Home Safety Council estimates -- the costs can be significant for apartment complex owners and building developers.

"When they start thinking about that, then they start lobbying against it," Weiss said.

Two years ago in Virginia, Sen. Frank Ruff, R-Mecklenburg County, introduced a bill to require carbon monoxide detectors in rental homes with carbon-based fuel appliances and those with attached garages or adjacent to parking spaces.

The General Assembly delayed action and asked for more study in the following year -- a year that included the July 14, 2006, carbon monoxide leak at a Roanoke College dormitory, which killed one person and sent more than 100 to hospitals.

Supporters of Ruff's bill, which included the Virginia State Firefighters Association, cited the Roanoke College incident when the measure came up again this year in a different form. Ruff's second bill applied only to college dorms and assisted-living facilities served by fuel-burning devices that might leak carbon monoxide, an invisible and odorless gas that according to the Centers for Disease Control and Prevention causes about 500 accidental deaths a year.

The bill ended up back with the Housing Commission for yet another study. But considering what happened in Blacksburg, this time could be different.

"We had that situation at Roanoke College last year and now we've got a situation at an off-campus apartment in Blacksburg," said House Majority Leader Morgan Griffith, R-Salem. "So I think we have to start looking at that as a safety issue."

Staff writer Michael Sluss contributed to this report.