Smoke and CO Alarms: The 10-Year and 5-Year Dates to Check

A smoke alarm should be replaced every 10 years from the date it was made, not the date you put it up. That is the guidance from the U.S. Fire Administration (USFA), and it is the date most people have never looked at. The Centers for Disease Control and Prevention (CDC) gives a shorter clock for carbon monoxide detectors: replace them per the maker's instructions, or every five years.

The date printed on the back of an alarm matters more than the green light on the front.

As the heating season starts, it is a good moment to look at both. This is a plain checklist built from the federal pages, with one buying tip at the end.

Where smoke alarms go

The USFA says to put alarms:

• Inside and outside each bedroom and sleeping area. It notes that a closed door may slow the spread of smoke, heat and fire.
• On every level of the home, including the basement.
• On the ceiling or high on the wall, following the manufacturer's instructions.
• As interconnected alarms, so that all of them sound when one does.

Test, replace, repeat

The CDC also suggests checking batteries when you change your clocks in the spring and the fall.

Carbon monoxide: the quiet one

Carbon monoxide, or CO, is a gas you cannot see or smell. The CDC says it comes from burning fuel in gas and oil furnaces, portable generators, charcoal grills, cars and trucks, small engines, stoves, lanterns, fireplaces and gas ranges, and that it can build up indoors. A blocked chimney can cause it to collect in a home. Running a car in an attached garage is a hazard even with the garage door open.

The CDC's page gives these annual figures but does not state the year:

• More than 400 Americans die each year from unintentional CO poisoning not linked to fires.
• More than 100,000 people visit an emergency department.
• More than 14,000 are hospitalized.

The USFA gives a lower number, more than 150 deaths a year from accidental, non-fire CO exposure, and credits the Consumer Product Safety Commission. The two counts differ and neither page explains why, so I would treat them as a range that shows the problem is real, not as a precise total.

Where CO alarms go

The advice from both agencies:

1. Put alarms near every sleeping area. The USFA says outside each separate sleeping area and on every floor.
2. Consider a detector with a digital readout, which shows the highest CO level in your home (CDC).
3. Run generators outdoors, more than 20 feet from windows, doors and vents (CDC), in open areas.
4. Keep the vents for your dryer, furnace, stove and fireplace free of snow and debris (USFA).
5. Have your heating system, water heater and other gas, oil or coal-burning appliances serviced every year by a qualified technician (CDC), and your chimney checked or cleaned each year.
6. Never heat your house with a gas oven, and never burn charcoal indoors (CDC).

Why I would not buy a used alarm

This is my own opinion, built on the date rule. Because the clock starts at manufacture, you usually cannot tell from the outside how much life a used smoke or CO alarm has left, or whether it has ever failed a test. A new alarm is a small purchase compared with what it protects. For everything else around the house, such as space heaters, ladders and appliances, used is often fine if you inspect it properly.

A short fall checklist for the DC area

1. Press the test button on every smoke alarm today.
2. Flip each one over and read the manufacture date.
3. Replace any that are 10 years old or more.
4. Check your CO detectors and replace any that are past the maker's date or five years old.
5. Book the annual heating system service.
6. Clear dryer and furnace vents of leaves and debris.

If you heat with a portable heater, read our space heater safety guide. If you buy a used dryer, our dryer guide shows what to check in the vent. Browse Buy Now for what is in stock and read the help page for how DealsDMV handles pickup.

The bottom line

Ten years for a smoke alarm, five for a CO detector unless the maker says otherwise, and a monthly test for the smoke alarms. Check the dates this week, and put a reminder in your phone for the next one.

If a relative lives alone, forward this and ask them to read the date on the back of their alarms.