If people sleep in a closed room where a charcoal fire is burning, they may die due to which gas?

Introduction / Context:
Incomplete combustion of fuels can produce dangerous gases. Charcoal fires, especially when used in poorly ventilated rooms, are a common cause of accidental poisoning. This question tests your understanding of which gas is mainly responsible for such deaths and why it is so dangerous even when people do not notice it during sleep.

Given Data / Assumptions:

• There is a charcoal fire burning in a closed or badly ventilated room.
• People are sleeping inside this room for a prolonged time.
• We must identify the toxic gas that can lead to death under these conditions.
• Options include carbon monoxide, carbon dioxide, methane, phosgene, and sulphur dioxide.

Concept / Approach:
Charcoal burns in limited air supply and can produce carbon monoxide, a colourless, odourless gas. Carbon monoxide binds strongly with haemoglobin in blood to form carboxyhaemoglobin, which prevents oxygen from being carried to body tissues. This leads to hypoxia and can be fatal. Carbon dioxide, methane, phosgene, and sulphur dioxide can be harmful in high concentrations, but the classic gas associated with charcoal burning deaths in closed rooms is carbon monoxide.

Step-by-Step Solution:
Step 1: Consider how charcoal burns. In a closed room the supply of oxygen is limited, and combustion may be incomplete. Step 2: Incomplete combustion of carbon rich fuels produces carbon monoxide (CO) rather than only carbon dioxide (CO2). Step 3: Carbon monoxide is colourless and odourless, so people do not detect it while breathing. Step 4: Carbon monoxide enters the bloodstream and binds to haemoglobin with much higher affinity than oxygen, reducing the ability of blood to carry oxygen. Step 5: As oxygen delivery to vital organs falls, people may feel drowsy, lose consciousness, and eventually die in their sleep if the exposure continues. Step 6: Therefore, the gas responsible for such deaths is carbon monoxide.

Verification / Alternative check:
Reports of carbon monoxide poisoning from charcoal stoves, gas heaters, and car exhausts in closed garages are very common. Safety guidelines always warn against using charcoal grills indoors or in closed tents because of carbon monoxide build up. Medical toxicology sources explain that elevated levels of carboxyhaemoglobin in blood confirm CO poisoning. This consistent real world evidence verifies that carbon monoxide is the correct answer.

Why Other Options Are Wrong:
Carbon dioxide: Produced in combustion but usually causes suffocation only at very high concentrations; most textbooks highlight carbon monoxide as the key danger from incomplete combustion.
Methane: Main component of natural gas; methane is combustible but not the primary toxic gas formed by burning charcoal in a closed room.
Phosgene gas: A toxic industrial gas once used as a chemical weapon; it is not formed in significant quantity from simple charcoal burning.
Sulphur dioxide: May be formed from burning sulphur containing fuels and can irritate airways, but charcoal fires and associated deaths in closed rooms are specifically linked to carbon monoxide.

Common Pitfalls:
A common mistake is to pick carbon dioxide because it is associated with breathing and is a combustion product. However, carbon dioxide is usually detected by discomfort and rapid breathing before it becomes lethal, while carbon monoxide is more insidious. Another pitfall is to think any poisonous gas might be involved without linking it to the specific combustion process and classical examples mentioned in environmental health chapters.

Final Answer:
People sleeping in a closed room with a charcoal fire can die due to carbon monoxide poisoning.