Smoke and CO Alarms on Each Level, Test Smoke Alarms Monthly
Smoke alarms and carbon monoxide (CO) alarms belong on every level of your home: the US Fire Administration (USFA) says to put smoke alarms inside each bedroom, outside each sleeping area and on every level, and the Consumer Product Safety Commission (CPSC) says to put CO alarms on every level and outside sleeping areas. Test smoke alarms every month, and replace the whole alarm 10 years from its manufacture date.
When a smoke alarm sounds, you may have less than 2 minutes to get everyone outside. If you suspect CO poisoning, get outside to fresh air right away, then call 911.
Smoke alarms
USFA explains (USFA smoke alarms):
- Where to install: inside each bedroom, outside each sleeping area and on every level.
- Test monthly: test them every month.
- Replace after 10 years: replace them 10 years from the manufacture date.
- Batteries: replace 9-volt batteries at least once a year; for hardwired alarms, replace the backup battery at least once a year; alarms with a 10-year lithium battery can’t have the battery replaced, so follow the manufacturer’s instructions for replacing the whole alarm.
- Interconnected: interconnected alarms are best, so when one sounds, they all sound.
- Two kinds of sensors: ionization and photoelectric alarms detect different types of fires; USFA recommends having both, or dual-sensor alarms.
- False alarms while cooking: don’t take out the battery; open a window or door, press the hush button, or move the alarm away from the kitchen or bathroom.
Carbon monoxide alarms
CPSC explains (CPSC carbon monoxide):
- Where to install: on every level and outside sleeping areas, battery-operated or with battery backup; interconnected alarms are best.
- Generators: never use a portable generator inside a home or garage, even with doors and windows open; use it outside only, at least 20 feet from the home, with the exhaust pointed away.
- Symptoms of poisoning: headache, dizziness, weakness, nausea, vomiting, sleepiness and confusion.
- If you suspect poisoning: get outside right away, then call 911.
CPSC says more than 200 people in the US die each year from accidental non-fire CO poisoning.
For who to call at 911, 988 and 211, see Call 911 in Emergencies, 988 for Mental Health, 211 for Help; for official alerts during outages and storms, see Free FEMA App Alerts for 5 Places, Texts Find Shelters. Who to notify when a detector in a rental isn’t working is left to our renting site’s guide to the detectors in your unit; how to test them at a final walkthrough when buying is left to our home-buying site’s guide to testing detectors.
What this article did not check
- How often to test or replace CO alarms: this CPSC page doesn’t say, so this article doesn’t either.
- Your state or city rules: this article did not check them.
Frequently asked questions
How many smoke alarms do I need?
USFA says one inside each bedroom, outside each sleeping area and on every level.
My alarm keeps going off when I cook. Can I take the battery out?
No. USFA says removing the battery can be a deadly mistake; open a window or door, press the hush button, or move the alarm away from the kitchen.
Can I run a generator in the garage during a power outage?
No. CPSC says never use a portable generator inside a home or garage; run it outside, at least 20 feet from the home.
What do I do if the CO alarm goes off?
CPSC says if you suspect CO poisoning, get outside right away, then call 911.
Sources and dates checked
All checked on 2026-10-31.
- U.S. Fire Administration, Smoke Alarms (page reviewed 2026-10-13):https://www.usfa.fema.gov/prevention/home-fires/prepare-for-fire/smoke-alarms/
- CPSC, Carbon Monoxide (no update date on the page):https://www.cpsc.gov/Safety-Education/Safety-Education-Centers/Carbon-Monoxide-Information-Center