Carbon monoxide poisoning — symptoms and what to do
⚠️ Carbon monoxide is colourless and odourless. If you suspect CO poisoning — leave immediately. Call 999 and the Gas Emergency line: 0800 111 999.
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Most likely cause & what to check
Carbon monoxide (CO) symptoms are often mistaken for flu: headache, dizziness, nausea, breathlessness, confusion, and tiredness. Unlike flu, CO symptoms improve when you leave the building and worsen when you return.
High concentrations cause collapse and death within minutes. Even low-level chronic exposure causes lasting neurological damage.
If anyone in the household is experiencing symptoms: open windows, get everyone (including pets) out of the building immediately, and call 999.
Do not re-enter the building until the emergency services have confirmed it is safe. Do not assume the symptoms will pass — CO can continue to rise.
Call the 24-hour Gas Emergency line: 0800 111 999. They will send an emergency engineer to isolate the gas supply and identify the source.
Every home with gas appliances must have at least one CO alarm. Fit one in every room with a gas appliance and one in every sleeping area. Test them monthly.
The most common CO sources in homes: poorly serviced boilers, blocked or cracked flues, gas fires, wood-burning stoves with blocked chimneys. Annual servicing by a Gas Safe engineer is the most important prevention step.
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