What to do if your carbon monoxide alarm goes off in the middle of the night?

Author: Prof. Verlie Wunsch  |  Last update: Friday, May 15, 2026

If the alarm on your carbon monoxide detector is going off in a continuous, shrill way, get outside to fresh air right away. Make sure you contact your emergency provider to give you the all-clear before re-entering your dwelling.

What to do if a carbon monoxide alarm goes off at night?

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.

What do you do if your carbon monoxide detector goes off for no reason?

Call for Help:

If you cannot identify a simple reason for the alarm (like a low battery) or if you suspect elevated levels of CO, call emergency services or the fire department immediately. Mention that your carbon monoxide alarm has gone off and you need an investigation.

Should I call 9-1-1 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.

Should I open windows if the carbon monoxide alarm goes off?

The open window will allow air to flow in and out, diluting the carbon monoxide. If possible, open windows or doors on both sides of the building, so that you get a cross-breeze.

What to Do When Your Carbon Monoxide Detector Goes Off

Will sleeping with window open prevent carbon monoxide?

Even if you keep the doors and windows open, it does not guarantee ventilation. Also, do not run these sources less than 20 feet from an open window, door, or vent so exhaust can escape into an enclosed space.

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.

How to tell if carbon monoxide is leaking?

What Are Signs of Carbon Monoxide in Your Home?
  1. Yellow or orange flames coming out of your gas appliances instead of the usual blue flame.
  2. Dark and sooty staining on or around gas appliances.
  3. Pilot lights that frequently blow out.
  4. Increased condensation on windows.
  5. Solid fuel fires burn much slower than usual.

Is 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 to disable carbon monoxide alarm?

First, look for a button called 'silence' or 'reset'. Hold this button down for 10 or more seconds. Release the button, and the LED lights should blink or turn back on. Your unit might also let out a singular beep.

Can carbon monoxide come from AC?

Air Conditioners Do Not Produce Carbon Monoxide. CO gas is a byproduct of incomplete combustion. It is produced when you burn fossil fuels such as natural gas, oil, propane, kerosene, gasoline, charcoal, or wood for heating or cooking purposes.

What does 4 beeps mean on carbon monoxide?

What Does an Emergency Alarm Chirp Mean? This meaning is probably the most self-explanatory. When your carbon monoxide detector chirps 4 times in a row and pauses, this means it has detected unsafe levels of carbon monoxide. This means your entire household should evacuate immediately and seek fresh air.

Will a carbon monoxide alarm go off again if you silence it?

No, the test/silence button only tests or silences the carbon monoxide alarm. To reset the alarm, the unit needs fresh air and time to burn the contamination off the sensor. Push and hold the silence button for 5 seconds to silence the alarm while contamination is being burned off the sensor.

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.

How long should you wait after carbon monoxide alarm goes off?

If your CO alarm is going off, you should immediately grab your family and pets and get into fresh air. Open any windows you can on your way out. Once outside, call 911. According to the CDC, the most common symptoms include headache, weakness, nausea, chest pain, confusion or vomiting [2].

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.

Should I worry if my carbon monoxide alarm goes off?

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.

Will opening a window help with carbon monoxide?

Opening windows helps the carbon monoxide quickly leave your home (as does opening doors). However, don't leave your exit path when getting out during this emergency to open as many windows as you can. Only open those that are along the way as you leave your home safely.

Should I call 9-1-1 for carbon monoxide?

Call 911 and report what is happening. Immediately leave your residence and wait for the fire department to arrive. Once there, we will send in a team with special monitoring equipment that will take air readings and determine the next appropriate action.

Can you stay in a house with a carbon monoxide leak?

If people in the home are exhibiting symptoms of CO poisoning, immediately leave the building and call your local fire department. In cases where residents are feeling fine, call your local gas utility company or a qualified technician to help identify the cause of the problem.

Who to call if a carbon monoxide alarm goes off?

CO detectors are very sensitive and designed to alert occupants before CO reaches dangerous levels. If your detectors go off, call 911 and evacuate the home. Be sure to notify them if anyone in the house is experiencing flu-like symptoms.

How long does it take for carbon monoxide poisoning to happen?

The longer you inhale the gas, the worse your symptoms will be. You may lose balance, vision and memory and even consciousness. This can happen within 2 hours if there's a lot of carbon monoxide in the air. The smaller an animal or person is, the faster they'll be affected.

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

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.

Can you recover from carbon monoxide poisoning on your own?

If you have a mild case of CO poisoning, you'll feel better just by going outside and breathing fresh air. More severe cases may require treatment with pure oxygen or hyperbaric oxygen therapy (HBOT).

How to test a carbon monoxide alarm?

How to test your carbon monoxide detectors to ensure they are working properly? To test your carbon monoxide detectors, press and hold the test button on the alarm. The detector will sound 4 beeps, a pause, then 4 beeps for 5-6 seconds. Refer to the user manual for your specific model.

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