TOH EE MING
Nepalis living in remote mountain villages, where temperature regularly drops below zero during the dreary winter months, burn dung and firewood inside their homes to stay warm. In urban areas, along with burning wood and charcoal, gas and kerosene heaters are used to keep homes and offices nice and toasty.
Smoke-filled rooms are, therefore, a common occurrence. Even when chimneys are installed to get rid of the smoke, inhabitants in these homes say they ‘miss’ the smoke because it provided a semblance of warmth. People also don’t always follow instructions when using their heaters. Sickness or death due to carbon monoxide (CO) poisoning is a nagging problem during the winter.
In busy hospitals like Bir, Patan, and Teaching, there are occasional cases where groups of people, who slept huddled together in closed spaces burning firewood, are admitted in semi-unconscious state. Just last month, Chinese and Italian tourists suffocated to death in their hotel rooms. Sometimes the diagnosis of CO poisoning is hard to make if a proper history is not taken.
The brain and the heart are the most sensitive target organs. Patients with minor exposures to carbon monoxide show vague symptoms like headache, lethargy, nausea, but higher doses may lead to confusion, seizures, and loss of consciousness. Cardiorespiratory arrest (heart and lung failure), hearing loss, dementia, and psychosis may also be features with higher doses. How carbon monoxide causes these effects is a fascinating study.
Haemoglobin, a protein in the blood, carries vital oxygen to various tissues of the body. Carbon monoxide has a liking for haemoglobin, which is 240 times that of oxygen, so it easily partners with the protein, unseating the oxygen molecule. Eventually when the haemoglobin circulates to the tissues in the blood, the tissues are bereft of any oxygen. This is when problems ensue.
There are also other forms of carbon monoxide exposure (more gradual exposure as opposed to acute poisoning discussed above) that many people in cities like Kathmandu and New Delhi encounter where air pollution is ubiquitous. CO is produced due to incomplete combustion of carbons in fuels, chiefly the automobile engine. It is likely that many people living in these polluted cities (for example policemen) have five to ten per cent of haemoglobin bound to carbon monoxide, particularly if they are smokers.
Because most houses in Nepal, especially in the hills are built poorly with generally little insulation (thus providing ample ventilation), even where firewood and dung is used for fuel, carbon monoxide poisoning is not as commonly seen as one would expect.
At high altitude, when trekkers use stoves for cooking or heating inside a closed tent, they become susceptible to poisoning. Since there is already a lack of oxygen at that height, exposure to carbon monoxide puts trekkers at a ‘physiologically higher’ altitude. Sudden cardiac deaths in trekkers in the mountains could be caused by carbon monoxide poisoning. A more common problem, acute mountains sickness which presents with headache and nauses is sometimes mixed up with carbon monoxide poisoning.
Prevention as always is better than cure and making sure that there is proper ventilation (before we use firewood, stoves, and heaters) is a good idea.