You may also notice black soot marks on front covers or panels on a gas fireplace. [3] X Trustworthy Source National Health Service (UK) Public healthcare system of the UK Go to source

Even when you aren’t burning a fire, a clean chimney will have an upward draft you can feel when you open the flue. If you can’t feel a draft, it’s another warning sign that CO levels could build up.

If the pilot light flame is blue, it could also be a sign that it’s not burning gas properly and CO is accumulating in the air.

Tension headache Dizziness or vertigo Fatigue or tiredness Confusion Difficulty breathing or shortness of breath Chest pains Stomach pains, nausea, or vomiting Loss of consciousness

People who spend more time indoors will be the most affected by the symptoms of CO poisoning.

Put the CO detector at least 15 feet (4. 6 m) away from your kitchen or any other cooking appliances. Check or replace the batteries twice a year. After 5–7 years, replace the entire detector unit. [14] X Trustworthy Source Centers for Disease Control and Prevention Main public health institute for the US, run by the Dept. of Health and Human Services Go to source When an alarm goes off, quickly leave and get to fresh air and check if you’re experiencing symptoms. Contact emergency services or your utility company to find the source of the leak or what caused the alarm to go off. [15] X Research source It usually takes 60–90 minutes for CO detectors to go off when carbon monoxide levels are above 50 ppm. If there are extreme or deadly levels above 330 ppm, then the detector will go off within 2–3 minutes of exposure. [16] X Trustworthy Source PubMed Central Journal archive from the U. S. National Institutes of Health Go to source

Whenever you use your fireplace, make sure you open the flue and wait to close it until the ashes feel cool so smoke can escape.

Never use an unvented gas appliance anywhere where someone is sleeping. Avoid using unvented gas appliances for longer than 4 hours at a time. [22] X Trustworthy Source Johns Hopkins Medicine Official resource database of the world-leading Johns Hopkins Hospital Go to source