What happens if my carbon monoxide alarm goes off?

Author: Abbie O'Reilly  |  Last update: Tuesday, July 22, 2025

Immediately evacuate the building to fresh air and safety. Call 9-1-1 once safely outside to report the incident and if there is anyone experiencing carbon monoxide poisoning symptoms like headaches, dizziness and vomiting. Do not return into the building until it has been cleared by first responders.

Should I worry if my carbon monoxide alarm goes off?

Yes, if a carbon monoxide (CO) alarm goes off, you should take it seriously. Here are the steps you should follow: Evacuate Immediately: Get everyone out of the building and into fresh air. Call 911: Once you are safe, call emergency services to report the alarm. They can send professionals to assess the situation.

Do carbon monoxide detectors give false alarms?

While CO detectors are designed to be reliable, various factors can cause them to beep erroneously. False alarms can be caused by incorrect installation, placement near a source of fumes or steam, or even a buildup of dust and dirt on the sensor.

What happens if a carbon monoxide alarm goes off and then stops?

If you have a carbon monoxide detector chirping and then it stops, it's important to take the situation seriously, even if the alarm is no longer sounding. Even if the alarm has stopped, get everyone out of the home to a place with fresh air. Contact 911 or your local fire department to report the incident.

Should I call the fire department if the carbon monoxide alarm goes off?

Yes, if a carbon monoxide (CO) alarm goes off, you should take it seriously. Here are the steps you should follow: Evacuate Immediately: Get everyone out of the building and into fresh air. Call 911: Once you are safe, call emergency services to report the alarm. They can send professionals to assess the situation.

What to Do When Your Carbon Monoxide Detector Goes Off

What are two warning signs of carbon monoxide poisoning?

The most common symptoms of CO poisoning are headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion. CO symptoms are often described as “flu-like.” If you breathe in a lot of CO, it can make you pass out or kill you.

What if carbon monoxide alarm goes off but no fire?

Your carbon monoxide alarm is going off for one of the following reasons: It is doing its job properly and detects CO pollution in the air. It is a false alarm caused by other household items. The detector is malfunctioning or the batteries need changing.

Does the fire department charge to check for carbon monoxide?

In most areas, the fire department does not charge to respond to carbon monoxide alarms or to check for the presence of CO in a residence. However, policies can vary depending on the jurisdiction or specific fire department. It's always a good idea to contact your local fire department for specifics on their policies.

Can anything else trigger a carbon monoxide detector?

Even with the doors and windows open, any of these activities can trigger carbon monoxide detectors. Using a grill inside the garage or near open doors and windows–Not only is barbecuing among the most common CO-producing activities, but it can also be a fire hazard when done too close to your home.

How to clear carbon monoxide from a house?

If no one is feeling symptoms, ventilate the home with fresh air, turn off all potential sources of CO - your oil or gas furnace, gas water heater, gas range and oven, gas dryer, gas or kerosene space heater and any vehicle or small engine.

What will my alarm do if it detects carbon monoxide?

When the carbon monoxide alarm senses a dangerous level of CO gas, the unit will emit a loud alarm pattern. The alarm pattern is four short beeps – followed by five seconds of silence – followed by four short beeps.

What to do if carbon monoxide alarm goes off and then stops in the UK?

If your CO alarm stopped beeping after being outside in the fresh air for 10 minutes, you may have a possible carbon monoxide leak in your home. We recommend calling your gas supplier or national emergency gas helpline on 0800 111 999 and await further instruction.

Why did my fire alarm randomly go off in the middle of the night?

Why did my fire alarm randomly go off in the middle of the night? This is likely due to one of the common causes like low battery, dirt buildup, humidity, or insects interfering with the sensor. Test the alarm and clean it thoroughly to try and resolve the issue. Make sure batteries are fresh and secure.

Should you open windows if carbon monoxide alarm goes off?

The Fire Department has specialized equipment to detect and measure amounts of CO in your home. Please do not open doors and windows before the Fire Department arrives, because this makes it difficult to determine the cause of any CO that may be present.

How to tell if carbon monoxide is in the air?

The best way to alert you and your family to unsafe levels of CO is to install a carbon monoxide detector. It works like a smoke alarm, sampling the air in your home and creating a loud alarm when levels of the gas are detected. It's important to evacuate your home immediately when your CO alarm sounds.

How to tell if a carbon monoxide alarm is false?

4 beeps and a pause: This means that there is carbon monoxide in the air and you should seek fresh air immediately and call 911. 1 beep every minute: This means that the alarm has low batteries and you should replace them. 3 beeps every minute: This means the alarm has encountered a malfunction and needs replacement.

Should I call 911 if my carbon monoxide alarm goes off?

My carbon monoxide alarm is sounding. What should I do? Call 911 and report what is happening. Immediately leave your residence and wait for the fire department to arrive.

What if the carbon monoxide alarm goes off then stops?

If you hear 4 beeps and then a pause, this is an EMERGENCY.

It indicates carbon monoxide has been detected and you should immediately evacuate your home or building and call 9-1-1.

What is the number one cause of carbon monoxide alarms?

How can carbon monoxide build up in a home? The most common causes of carbon monoxide building up are incorrectly installed or poorly maintained or ventilated appliances – like stoves and hot water heaters.

How do you know if you have had carbon monoxide poisoning?

A common source is unvented space heaters. Symptoms of CO poisoning include headache, dizziness, weakness, nausea and vomiting, rapid heartbeat, shortness of breath, seizures, chest pain, disorientation, and loss of consciousness.

Is a carbon monoxide alarm an emergency?

If it still sounds, call the fire department. If the CO alarm sounds, immediately move to a fresh air location outdoors or by an open window or door. Make sure everyone inside the home is accounted for. Call for help from a fresh air location and stay there until emergency personnel.

How much does it cost to get your house checked for carbon monoxide?

Professional carbon monoxide testing can cost from $100 to $200+. But, most homeowners usually have carbon monoxide detectors which can range from $20 to $150+, according to Home Advisor, depending on the detector type.

Who do I call if my CO2 alarm goes off?

If the alarm sounds, vacate the house. Then, it's best to call 911 or the fire department to come out and test for the source of carbon monoxide. Once they've identified what is causing carbon monoxide to be released in your home, you'll need to contact a licensed professional to service the offending appliance.

What happens after carbon monoxide alarm goes off?

What to do if a carbon monoxide alarm goes off. If your carbon monoxide alarm is beeping, immediately get out of the building and call the relevant helpline for the fuel type. The gas emergency helpline is 0800 111 999. Call a registered engineer to check all your fuel-burning appliances.

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