Carbon monoxide alert: take care when burning fuel

Powerhouse Museum collection, object 2000/113/7. Gift of Cooranbong Colliery - Powercoal Pty Ltd.
Powerhouse Museum collection, object 2000/113/7. Gift of Cooranbong Colliery – Powercoal Pty Ltd.

Coal miners are very aware of the risks posed by fuels. Whenever they go underground they carry self-rescuers like this one, which turns toxic carbon monoxide into harmless carbon dioxide. News that a Sydney family was rushed to hospital recently suffering from carbon monoxide poisoning demonstrates that the rest of us should be just as aware of the dangers.

Most common fuels have molecules that contain carbon and hydrogen atoms. Some contain other elements as well, but these are the key ones to be aware of. When such fuels burn in a well-ventilated space, carbon combines with oxygen from the air to form carbon dioxide, and hydrogen combines with oxygen to form water.

If you prefer to see that in symbols, the reaction of methane (the main constituent of natural gas) with oxygen is written

CH4 + 2O2  –>  CO2 + 2H2O

Unflued fuel heaters in poorly ventilated rooms, like the coal fire implicated in the recent incident, are a recipe for a more insidious reaction. The oxygen in the room is depleted as the fuel burns. In the absence of sufficient oxygen, carbon monoxide (CO) forms instead of carbon dioxide. This gas is colourless, odourless and dangerous. It causes headaches, drowsiness, nausea, organ damage and death.

While the water vapour that results from combustion of fuel is not an immediate threat to life, in a poorly ventilated home it can condense on walls and promote the growth of mould. For many people, mould spores cause respiratory diseases or allergies, and these can lead to death.

The lesson is that all fuel-burning appliances should be fitted with flues to carry the products of combustion outside, and that homes should be ventilated, especially in the depths of winter. The beginning of winter is a good time to check that flues aren’t blocked and heaters are working correctly.

Candles also produce carbon monoxide in low oxygen conditions, so remember that candle wax is a fuel that should be treated with as much caution as natural gas, kerosene, coal or wood – in fact, more caution should be exercised because candles cause a large number of house fires. And cigarettes, and some incense sticks, produce unhealthy levels of carbon monoxide even in well-ventilated rooms.

Australian scientists are developing a new carbon monoxide detector, based on what happens in our bodies when we are poisoned by the gas. Carbon monoxide is dangerous because its molecules attach to haemoglobin in our bloodstream, preventing it from carrying out its vital role. Haemoglobin transports oxygen from the lungs to all the cells in the body, unloads it there, picks up the waste product carbon dioxide and carries it to the lungs for exhalation. That’s why gumming it up with carbon monoxide can be fatal.

In a clever example of biomimicry, the new detector will incorporate sensor molecules that are similar to the key reactive part of haemoglobin. The plan is to print the sensor and other device components onto flexible plastic to make small, cheap electronic detectors that could be attached to any fuel-burning device or gas mask. As well as alerting everyone to immediate danger, the detectors could serve an educational purpose, reminding us that vigilance is necessary wherever fuel is in use.

Written by Debbie Rudder, Curator.

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