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Safety card

Your carbon monoxide alarm is sounding

The short answer

Treat it as real. Get everyone outside into fresh air, then call 911. Carbon monoxide has no color or smell, so “I don’t smell anything” tells you nothing.

Fresh air firstCarbon monoxide comes from fuel-burning appliances, vehicles and generators. Early symptoms (headache, dizziness, nausea, confusion) can feel like the flu.

Related

Smoke or CO alarm chirping, even with a new batteryYou smell gasFurnace short-cycling (turns on and off quickly)

Written from

Original casaq guidance, updated 2026-10-05. General guidance, not a diagnosis; licensed-pro review pending. Severity levels: Emergency now / Today / This week / This month / Watch. Send a correction.

Emergency now

Your CO alarm is sounding

Get to fresh air first. Then call.

Do this right now
  1. Get everyone outsideCarbon monoxide has no smell. Don't stop to find the source or open every window.
  2. Call 911 from outsideTell them if anyone has a headache, dizziness, nausea, sleepiness or confusion.
  3. Stay outWait for responders to say the air is safe before going back in.

Afterwards, have every fuel-burning appliance checked by a qualified technician before using it again. If the alarm only chirps once a minute, that is usually a low battery or end of life, not CO: see the alarm-chirping card.

Call 911
casaq triage library · general guidance, not a diagnosis · licensed-pro review pendingCorrections