The first five minutes
- Get everyone out to fresh air.
- Call 911 or the fire department from outside or from a neighbor's house.
- Do a head count. If someone is still inside or can't get out, tell the dispatcher right away instead of going back in.
- Stay out until responders give permission. An alarm that goes quiet is not permission.
CPSC's guide for dispatchers and responders tells residents not to take time to open windows before leaving, unless someone is unconscious or can't leave. Going room to room opening windows only delays getting out.
What to tell the dispatcher
You don't need to know the cause. Give them what you already know:
- Your address and that a CO alarm went off.
- Whether anyone has a headache, dizziness, nausea, confusion or chest pain, or was hard to wake.
- Whether anyone is still inside.
- What was running: furnace, boiler, water heater, gas range, fireplace, generator, or a car in an attached garage.
Symptoms count even without an alarm
The CDC lists headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion as common symptoms. CPSC describes them as flu-like but without a fever. CO has no color or smell, and people who are asleep or drunk can die before they notice anything. Infants, older adults and people with heart disease, anemia or breathing problems are at higher risk. The CDC counts more than 400 deaths and more than 14,000 hospitalizations from CO each year in the U.S.
If several people in the house feel unwell at the same time, especially when the heat is running, go outside and call 911 whether or not an alarm is sounding. The CPSC responder guide says people with symptoms should be checked by EMS and should not drive themselves to a doctor or hospital.
Chirp versus alarm
The CPSC and NFPA CO alarm lesson treats a chirp as a low-battery signal: replace the battery right away, and if the alarm still sounds afterward, call the fire department. Beep patterns differ by model, so keep the manual or check the label on the back of the unit. If you can't tell which signal you're hearing, treat it as an alarm and go outside. Testing monthly with the test button tells you the circuitry works, but CPSC notes it doesn't check sensor accuracy.
After you're allowed back in
If responders find a faulty appliance, don't run it until trained personnel have serviced it. CPSC also says that if the alarm sounds again within 24 hours of re-entry, you should repeat the whole process: get out, call, and stay out. Then have a qualified technician check every fuel-burning appliance, and make sure no vehicle is left running in an attached garage. Our guide to garage-to-house separation covers the door and wall details that keep exhaust out of living space.
Ask the technician to write down which appliances and vents were checked, what they found, and whether anything was left unchecked. CPSC recommends a yearly heating inspection that includes chimneys and flues for blockages, corrosion and loose connections.
Pennsylvania rules worth knowing
Pennsylvania's Carbon Monoxide Alarm Standards Act (Act 121 of 2013) does two things for homeowners and renters:
- Sellers must disclose on the property disclosure statement whether CO detectors are installed. If you're buying, read that line alongside the city records in a Philadelphia sales certification.
- In buildings with three or more units that have a fossil-fuel heater or appliance, a fireplace or an attached garage, the owner must provide working CO alarms near bedrooms and the fuel source at move-in. After that the tenant tests the alarms and replaces the batteries.
Renters in Philadelphia can also check the rental license for their address. For single-family homes and anything beyond the state act, ask your township or borough code office.
Where alarms go
CPSC says to put CO alarms on every level of the home and outside sleeping areas, and interconnected alarms are best. Keep them out of kitchens, away from heating vents and not directly above fuel-burning appliances. The CDC says to replace them on the manufacturer's schedule or every five years.