"Coal gas" (which can be produced from coal, charcoal, or even wood) used to be widely plumbed through major cities into people's homes where it was used for things like heating and cooking. Coal gas is basically the product of incomplete combustion and it contains a various mixture of different combustible and non-combustible gases including hydrogen and most importantly large amounts of carbon monoxide.

And this is precisely why there is the "trope" of committing suicide by putting your head in the oven, because with an oven fueled by coal gas if you blow out (or don't light) the pilot light and turn on the gas you will rapidly build up an area of high concentrations of carbon monoxide inside the oven. And if you put your head in there you will very quickly lose consciousness and then die as the carbon monoxide begins to convert all of the hemoglobin in your blood incapable of transporting oxygen.

Eventually people, mostly, grew wise to the risks of piping such potent poisons into people's homes and switched to the comparatively much safer natural gas (especially as it began to become more available with the boom in the petroleum industry).

However, I'll point out that natural gas usage is actually very old, dating back to the early iron age in some places, like parts of China which used bamboo pipes for drilling wells for shallow natural gas deposits and transporting the gas to the point of use, most especially to evaporate the water from brine in order to produce salt.