How often should I test and replace smoke alarms?

• “Use the test button to test your smoke alarms at least monthly.” (American Red Cross)
• “If you have battery-powered smoke alarms, replace the batteries at least once a year.” (American Red Cross)
• “Replace your smoke alarms every 10 years.” (American Red Cross)

• Replace the batteries in carbon monoxide alarms at the same time as the smoke alarm batteries (American Red Cross).
• Kidde, an alarm maker, recommends replacing carbon monoxide and combination alarms every seven to ten years, depending on the model.

In a house you just bought, you probably don't know. Kidde: “check the back of the alarm for the manufactured date.”