What is Carbon Monoxide?

Carbon Monoxide (CO) is a colourless, tasteless, odourless, poisonous gas produced by incomplete combustion of fuel. This can include 'cold' or badly tuned engines.

It is estimated that road transport is responsible for almost 90% of all carbon monoxide emissions in the UK, and thus ambient concentrations will generally be highest close to busy roads. Monitoring data suggests that annual average Carbon Monoxide concetrations have been decreasing over the last few years, and it is now almost always in the "low" banding. This decrease is due to improved vehicle engine efficiency and the introduction of catalytic converters, which reduce some of the pollutant gases coming out of exhausts.

Badly ventilated domestic fuel appliances (gas, oil or solid fuel) can lead to high indoor concentrations, as can smoking.

Carbon Monoxide affects the transport of oxygen around the body by the blood. Breathing in low levels can result in headaches, nausea, tiredness and difficulty in thinking clearly. Exposure to high concentrations can kill, but this would almost never happen outdoors.

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