Snow hikes CO threat

Having snow block exhaust vents outside your home can force lethal carbon monoxide gases back inside a building, said Brookline Fire Lt. Mark Jefferson.

And if you don’t have a carbon monoxide detector or need to change the batteries, you might be putting you and your family at risk.

Jefferson said homes with heating systems that rely on “power venters,” which often have vents low to the ground outside a home, are particularly at risk.

“Furnaces are so efficient now, they don’t reach that temperature that they vent up the chimney,” Jefferson said. “If [a vent] gets blocked by snow, combustion gas can back up into your living space.”

The state Board of Fire Prevention defines a power venter as “an electrically operated mechanical fan that is designed and listed to produce a negative draft at the heating appliance to exhaust combustion gases.”

But safety is not just about shoveling your snow in the right place, Jefferson said.

The best way to protect against carbon monoxide poisoning is to install a detector on the wall or use a plug-in unit with a battery backup, he said.

“As opposed to a fire, where you smell smoke or see fire if you’re awake, you can be awake and perfectly functional and not be aware your furnace is backing up,” Jefferson said.

Contrary to how a smoke detector should be installed — high on a wall or on the ceiling — Jefferson said it doesn’t matter at what height a detector is installed.

“Smoke and heat rise, but carbon monoxide is more like a perfume that doesn’t rise but expands and permeates in the space,” he said.

Carbon monoxide poisoning is similar to flu-like symptoms, he said, but said there is no real way to distinguish the two without a detector on every floor of a home and within 10 feet of any bedroom.

“It’s so important to have carbon monoxide detectors because they’re going to activate long before anyone’s feeling ill,” he said.

Jessica Scarpati can be reached at jscarpat@cnc.com.

· Who needs a carbon monoxide detector?

As of March 31, 2006, anyone who owns residential property that contains fossil-burning fuel equipment or contains enclosed parking, such as an attached or enclosed garage.

Residents in public housing have until Jan. 1, 2008, to install detectors.

Since September, the state fire prevention board added hotels, motels, hospitals, nursing homes, prisons and state-licensed day-care facilities to that list. They had until Jan. 1.

According to state law, landlords must install carbon monoxide detectors in each unit. They also must maintain, test and replace batteries on the alarms once a year.

· Where do I put an alarm?

Detectors are required on every level of a home, including finished basements and attics. Alarms must be within 10 feet of bedroom doors.

· What do I do if an alarm goes off?

Call 911 and leave the building immediately. If you experience headaches, fatigue, shortness of breath, nausea and dizziness, you may have carbon monoxide poisoning.

Source: Massachusetts Department of Fire Services