Carbon monoxide poisoning a slow slip into death
RECENT cases of people being found dead in their cars of suspected carbon monoxide poisoning have once again raised the issue of car safety and the dangers of sleeping in stationary vehicles with the engine running.
Carbon monoxide is an odourless gas that has long been perceived as toxic, and is often used by those who commit suicide.
But contrary to common assumption, the natural level of carbon monoxide in the environment is not toxic or poisonous.
It is the dose and length of exposure that determines the toxicity or extent of poisoning, explains Professor Dr Chin Beek Yoke, who specialises in physiology and toxicology, and is a faculty member in the medical biotechnology programme and dean of industry partnership and engagement at International Medical University.
“In cases of carbon monoxide poisoning, the victims are almost always inadvertently or accidentally exposed to very high doses for a long period.”
The gas is generated from the burning of fossil fuel, says Chin. Even when we light a match, carbon monoxide is created.
Every time we burn petrol or diesel, carbon monoxide is generated by the vehicle engine. This gas is then funnelled away from the engine through the exhaust pipe into the open air, explains Chin.
In a moving vehicle, the gas will be diffused from the cabin, thus preventing a hazardous build-up.
However, if the engine is running in a parked car for a long period, the carbon monoxide from the exhaust can accumulate and leak back into the vehicle cabin, exposing the sleeping occupant to high concentrations of the gas.
High exposure to carbon monoxide in an enclosed, unventilated space, such as a locked car, poses a very serious risk, says Dr K. Sashetheran, senior resident medical officer (emergency department) Gleneagles Hospital
Kuala Lumpur.
Carbon monoxide is colourless, odourless and tasteless, he says. We can’t see, smell or taste it. Most people who drift off to sleep in parked cars with the engine running do not realise what’s happening to them.
It is important to check the exhaust and undercarriage of your car and have your vehicle routinely inspected. A damaged or even clogged exhaust can result in such incidents, says Dr Sashetheran.
As carbon monoxide levels in an enclosed area, such as a car, slowly build up, the victim becomes drowsy, fatigued and end up becoming unconscious.
If the windows are wound down a little, there would be air circulating and the concentration of carbon monoxide in the vehicle would be less.
Dr Sashetheran says when someone is awake and exposed to carbon monoxide, the initial symptoms would be headache, nausea, dizziness, vomiting and chest tightness or shortness of breath.
When the level exceeds a certain threshold, confusion sets in and some people may suffer seizures.
“It can happen slowly or gradually and the risk depends on the concentration in that enclosed space.”
If the concentration of the gas is low and exposure is only for a short period, the person may experience a headache or other initial symptoms and may decide to open the car door and step outside to refresh themselves.