Turning on the heat? Test CO alarms and clear vents, state fire officials say

As furnaces, boilers and wood stoves come back on, the Massachusetts Department of Fire Services offers a short list of habits that reduce both risks.

Carbon monoxide: the invisible hazard

CO has no color or smell, so an alarm is the only reliable warning. State law, known as Nicole's Law, requires CO alarms on every habitable level of a Massachusetts home.

• Test alarms monthly.
• Replace them every five to seven years, depending on the model; the manufacture date is on the back.
• After each storm, clear snow from dryer, furnace, boiler and fireplace vents, and never aim a snowblower at them.
• Never heat your home with a gas oven or stove.

Early symptoms include headache, fatigue, dizziness and nausea, and exposure during sleep is especially dangerous. If the alarm sounds, get outside and call 911.

Fire prevention around heat sources

• Have the furnace and water heater checked by a professional every year.
• Have chimneys and flues inspected and cleaned annually, and use a fireplace screen.
• Keep anything that can burn at least 3 feet from space heaters, wood stoves and fireplaces.
• Store ashes in a lidded metal container placed well away from the house, garage and porch.
• Keep gasoline and paint supplies away from pilot lights.

Space heater rules

Use a space heater only as a supplement, plug it directly into a wall outlet rather than an extension cord or power strip, and turn it off when you leave the room or go to bed. Portable kerosene and propane heaters are illegal for home use in Massachusetts, and new wood stoves require a building permit.