An invisible killer in the home

As many as 240 people a year die from carbon monoxide poisoning.

First Alert, one of the manufacturers of carbon monoxide detectors, received a letter from a grateful parent earlier this year. She had bought her two children, who were students, detectors for Christmas. Rather grudgingly, they had taken them back to their respective colleges - to find that the alarms signalled within the first week. It appears that the gas appliances in both sets of accommodation were giving off carbon monoxide (CO) gas. The mother claimed that without the alarms her children could have been killed.

She was right to be thankful. It is estimated that as many as 240 people die each year when they inhale carbon monoxide. Badly installed and poorly maintained fuel-burning appliances (such as oil heaters or gas fires), blocked chimneys or lack of ventilation around appliances are usually to blame.

Everyone is at risk, but anyone moving into cheap, rented accommodation where appliances may not have been serviced regularly is particularly vulnerable. That includes more than a million school-leavers moving away from home in the next few weeks.

"I dread the autumn and winter months, because that is when many of the tragedies happen," says Stephanie Trotter, president of the consumer group CO Gas Safety. "When young people move away from home, the state of the fire or boiler is often the last thing on their mind. They may not even be aware it could be dangerous. In fact, in an effort to save heat they might do their utmost to block off vents and draughts. They might ignore symptoms of poisoning (tiredness, headaches, dizziness, sickness), thinking that a dose of 'flu or a bad hangover is to blame."

Trotter has seen some tragic cases. Like that of the 19-year-old Aston University student Clare Watkinson, who came home from college a couple of weeks before the end of the autumn term, 1991, complaining of tiredness and frequent bad headaches. When she returned to college, the leaking CO gas that had caused Clare's low-level symptoms killed her. Tracy Murphy, also 19, found it increasingly hard to get up in the morning after moving into her bedsit in Hull. One morning in late November 1993, she didn't get up at all.

Carbon monoxide detectors, which are designed to sound the alarm when this lethal, odourless, colourless gas is present, would appear to be an essential purchase. Sales for devices have soared, say leading manufacturers such as First Alert and SF Detection. The Consumers' Association called for the mandatory fitting of detectors in rented accommodation with fuel- burning appliances earlier this year.

The CA, CO Gas Safety, the Gas Consumers Council and the Royal Society for the Prevention of Accidents all warn that people should never be tempted to use detectors as a fail-safe warning of danger, or as a substitute for proper maintenance of their appliance. Detectors don't have a British Standard, and it doesn't look as if there will be one until early next year. Discussions at the British Standards Institute are continuing over the problem of sensitivity and siting. They want the alarms to be as sensitive as they need to be, but not so sensitive that they set off false alarms and so come to be ignored. It is also unclear where the detector should be placed. Forensic scientist Tom Magner, who has worked on many CO poisoning cases, points out that whereas smoke is predictable in its behaviour, CO gas, because it has a density close to air, may sink to the bottom of the room or drift to the top, depending on temperature and air currents.

Even when these issues are resolved, and a standard introduced, the fact remains that detectors can only act as a secondary precaution. The first line of protection for anyone living in rented accommodation is the law, and their own common sense.

Last October the Government introduced a law requiring landlords to maintain gas appliances, to have them checked at least once a year by a Corgi-registered installer, and to keep a record to prove it. The Health and Safety Commission (HSC) is proposing that this law is amended to specify that the safety check should cover the flue (the smoke duct in the chimney) as well as the appliance. A consultation document was published by the HSC earlier this month. If approved in the next session of Parliament, the amended law could come into force next April.

Common sense is vital. Not only can landlords not always be trusted. There is also evidence to suggest that some appliances have proved unsafe, even after being checked. Tightening up the legislation may help, as will moves to ensure that gas installers are properly trained (at the moment, only the firm has to be Corgi-registered, not individual employees). But it is clear that tenants should still keep their eyes open for tell-tale warning signs (see opposite) and arrange for a second safety check if they are not happy.

WHAT YOU AND YOUR LANDLORD SHOULD DO

If you're buying a detector, the Gas Consumers Council recommends you choose one with:

n an audible and visible alarm

n siting, use and maintenance instructions

n advice on what to do if the alarm is triggered

n battery power and a low-level warning light.

Devices to look out for:

n First Alert FACOE battery-powered detector, around pounds 30, available at B&Q, Do It All, Homebase and DIY stores. Call 0500 719720 for stockists.

n SF Detection's mains model detector - the SF310 - is available at pounds 58. Call 01202 665330 for stockists.

n Card-type indicators such as PH Smoke Products SleepSafe (from Robert Dyas and Texas) are cheaper, around pounds 5 for two, but are useful only to show early signs of carbon monoxide build-up. They should never be relied upon as an emergency warning device.

If you're moving into rented accommodation this autumn:

n Ask to see the landlord's Standard Gas Safety Report form proving any fuel-burning appliance has been checked in the last 12 months. If possible, confirm the flue was checked at the same time. If the landlord resists, contact your regional Health & Safety Executive office and/or the local Gas Consumers Council (number on the back of gas bills). You can call the HSE's Gas Safety Action Line on 0800 300363 for more advice.

n Warning signs: the pilot light keeps going out; there is an orange or yellow, rather than blue, gas flame; scorching or soot marks near the flame.

n Never block off vents and beware blocked chimneys and excessive draughtproofing.

n Never ignore inexplicable nausea, dizziness and headaches. If worried, report suspected CO poisoning to your doctor and ask for a blood test.