In cases where a person has died due to a faulty gas boiler, or when they were trying to cook food inside a closed tent, or in other such similar circumstances, the culprit is carbon monoxide. It is particularly insidious as it is completely odourless.
In the days before modern gas detectors were invented, miners used to take caged canaries underground with them, as a kind of early warning system. Birds are more sensitive to carbon monoxide than human beings, so if a bird keeled over, they knew it was time to head for the surface pretty quickly!
Carbon monoxide is so toxic because of its negative effect on the blood’s ability to transport oxygen round the body. At very low exposures the symptoms of carbon monoxide poisoning are tiredness and headaches. As exposure increases, the next stage is nausea, followed by unconsciousness and then death.
Health and Safety professionals talk about ‘exposure’ to toxic gases. This refers to the concentration of such gases in the air and the amount of time contaminated air is inhaled.
Breathing in a relatively low concentration over a prolonged period can be as dangerous as inhaling a high concentration over a short period. For this reason, workers on construction and similar sites are at great risk, since they may be exposed to a steady concentration of toxic gases all day long.
All internal combustion engines emit carbon monoxide. Petrol engines produce significantly more than diesel engines, while the amount emitted from gas engines varies, depending on how sophisticated they are. Carbon monoxide emissions can be effectively reduced by using a catalytic converter.