MADISON, Wis. -

Only one out of every five Dane County school districts has carbon monoxide detectors in its buildings, a WISC-TV investigation revealed.

Wisconsin law doesn't require the devices in schools, despite a requirement that homeowners maintain one on every level of their homes. The state also doesn't mandate the alarms in larger day care centers, although providers in single-family and two-family homes are covered under current law.

States' laws have come under scrutiny after potentially lethal levels of carbon monoxide at an Atlanta elementary school that didn't have alarms sent 50 people to the hospital and led to the evacuation of 500 others. Georgia also doesn't require detectors in schools.

"Like many codes, whether it's fire codes or building codes, they come out of tragedy," said Ed Ruckriegel, Madison's fire marshal. "I see the carbon monoxide alarms as important as smoke alarms, because it's one of those things that occurs when people aren't aware of it."

The colorless, odorless threat, often called "the silent killer," sickens Wisconsinites year after year. On Madison's near west side, six people were transported to hospitals after a carbon monoxide evacuation of Trinity United Methodist Church in 2009.

The next year, church members went to the state Capitol to advocate for a law that would require the devices in homes and where people gather during the day. Four alarms installed after the first scare caught a problem with the church's old gas stove a few months later before it sickened anyone, said Jerry Tifft, chairman of the church's board of trustees.

"They are the difference between life and death," said Tifft, who's been a church member since 1955. "I think we had a little connection here that probably was looking out for us that day."

State legislators passed a law that went into effect in 2011, closing a loophole and mandating carbon monoxide detectors in buildings where people sleep. About 72 percent of the incidents happen in single-family homes, said Rep. Gordon Hintz, D-Oshkosh.

But neither school districts nor the fire prevention community pushed to extend the law to schools then, and there's no discussion of it now, Hintz said.

"You don't want to fly blind of these things (as a legislature)," he said. "If it's something that we should look at, then I'm going to listen to them. We know we're not going to be able to do everything, and there's a cost to everything."

The state Department of Public Instruction was also not aware of any effort to require detectors in schools, said Patrick Gasper, a spokesman for the agency.

In Dane County, McFarland, Mount Horeb and Cambridge facilities managers said all of their school buildings have carbon monoxide detectors, although not all had them near every gas-powered appliance.

Every other district in the county, plus Janesville and Beloit in Rock County, does not have the alarms in their schools, and no administrators said they planned to install them. Oregon School District administrators didn't return multiple phone calls seeking comment.

While state law doesn't mandate that large day care facilities install the devices, five out of the six Madison providers that WISC-TV randomly contacted had them.

None of the providers or school district administrators said they had ever gone off.

Some of the facilities managers that didn't have carbon monoxide detectors said their buildings' heating systems were advanced and that the chance of a leak was minimal. Others cited the cost associated with installing the alarms.

"To say, 'We need to install these big systems" -- they already exist," Ruckriegel said. "A lot of those buildings already have alarm systems, so it would not be great cost to add a carbon monoxide detector to the fire alarm system."

School administrators across the state may be preoccupied with how to pay for school security measures after the Newtown, Conn., school shootings, and carbon monoxide detectors may not be top of mind, Hintz said.

"I know school districts around the state are trying to wonder, 'Well, how do I balance demands from parents to keep kids safe with the cost restrictions the legislature has imposed on districts?'" he said.

Wisconsin became the 25th state to require carbon monoxide detectors in people's homes. Only two states, Connecticut and Maryland, require them in schools.

Two others, Texas and Rhode Island, mandate them in child day care facilities, according to data provided by the National Conference of State Legislatures.