Carbon monoxide is a colourless, odourless gas produced by the burning of fuels, including gas, oil, wood and coal.

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Over a period of 10 years, she lived with low levels of Carbon Monoxide, and the colourless odourless gas slowly poisoned her.

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"The thing about carbon monoxide poisoning is that the carbon monoxide itself is odourless, colourless, tasteless so it's a silent killer, " he said.

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Joyce Bridgewater, from Camelford, will have to use a wheelchair for the rest of her life after breathing in the odourless gas for a decade.

BBC: Gas body urges appliance checks in Cornwall

It enables people to detect leaks of normally odourless natural gas.

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CFCs are a smuggler's dream: odourless and colourless, they can be used in everything from air-conditioners to foam, and their replacements never quite match up to them.

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More usually performed on animals, the creature is given time to get used to the mirror and is then anesthetized and marked on the face with odourless, non-tactile dye.

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Joyce Bridgewater, from Camelford in Cornwall, suffered low-level CO poisoning by breathing the colourless odourless gas in her home over a period of 10 years and now has to use a wheelchair.

BBC: Warning over rise in carbon monoxide fatalities