• Description

Carbon Monoxide (CO) is a poisonous gas produced by incomplete burning of carbon-based fuels, including gas, oil, wood and coal. Known as the “silent killer” because we cannot see it, we cannot smell it and we cannot taste it. Carbon Monoxide is only produced when the fuel does not burn properly.

When CO enters the body, it prevents the blood from absorbing oxygen and therefore delivering oxygen to cells, tissues and organs. Exposures at 100 ppm or greater can be dangerous to human health. The most common symptoms of carbon monoxide poisoning may resemble the flu and also including headache, nausea, vomiting, dizziness, lethargy and a feeling of weakness.

As the levels CO increases so does the severity of the symptoms and the time needed to cause an affect.



35 ppm (0.0035%)

Headache and dizziness within six to eight hours of constant exposure

100 ppm (0.01%)

Slight headache in two to three hours

200 ppm (0.02%)

Slight headache within two to three hours; loss of judgement

400 ppm (0.04%)

Frontal headache within one to two hours

800 ppm (0.08%)

Dizziness, nausea, and convulsions within 45 minutes; insensible within 2 hours

1,600 ppm (0.16%)

Headache, tachycardia, dizziness, and nausea within 20 minutes; death in less than 2 hours

3,200 ppm (0.32%)

Headache, dizziness and nausea in five to ten minutes. Death within 30 minutes.

6,400 ppm (0.64%)

Headache and dizziness in one to two minutes. Convulsions, respiratory arrest, and death in less than 20 minutes.

12,800 ppm (1.28%)

Unconsciousness after 2-3 breaths. Death in less than three minutes.

Common sources of carbon monoxide in the home include faulty central heating systems, gas appliances and fires. Blocked flues and chimneys mean the gas can't escape and is inhaled. About 50 people die each year in the UK from accidental carbon monoxide poisoning and 200 people are seriously injured.

Carbon monoxide poisoning is preventable, so it's important to be aware of possible causes and how to minimise the risk of exposure by putting these safety tips into practice:

  • Have chimneys and flues checked regularly
  • Make sure gas appliances and heating systems are inspected every year
  • Fit carbon monoxide alarms - available from DIY stores
  • Never run cars, motorbikes or lawnmowers in a closed garage

The best way of protecting against CO poisoning is to be aware of the dangers, and identify the appliances that could emit CO gas. Make sure that your household appliances are safe and well maintained. Boilers, cookers, heating systems, and appliances should be installed and regularly serviced by a reputable, registered engineer. Make sure that rooms are well-ventilated, and do not block air vents.

If your home is double-glazed, or draught-proofed, make sure there is still enough air circulating for any heaters that are in the room. Make sure that all chimneys and flues are kept clear. Fit an extractor fan in your kitchen.

The most reliable way of checking CO levels in your house is to install an audible CO alarm.