By ANNA SLEEPERS, CNNMoney | January 11, 2017 11:15:18A recent study from the University of Bristol showed that chimneys emit more CO2 than traditional homes, and they can get a bit dusty.
But while chimneys are a serious source of CO2 pollution, the issue of why they smoke is much more complex.
The researchers found that the smoke in chimneys is a mix of gases and vapors, and not just CO2.
“There are two different types of CO 2 emissions in a chimney,” said Andrew Wilson, the lead author of the study.
“The one that we have identified is a mixture of gases, mainly carbon dioxide and water vapour, that are produced by the combustion of wood and wood products.”
“These gases are the main component of the smoke, and are also the most visible in the smoke from a chimny,” he added.
The second type of CO² emission is water vapours, and these are emitted by the breakdown of materials.
“In the smoke of a chimn, there is no such thing as water vapors,” said Wilson.
“So the gases we have found are not CO2 and are water vapoured.”
Wilson said that the main source of the water vaporous gases in the chimneys was the wood itself, which is a natural source of water vapouring.
“It is an open question as to why chimneys have this particular water vapourizing effect,” he said.
“If you look at the carbon dioxide emitted by wood combustion, it would seem that the water is the main contributor to that.”
But Wilson said the amount of water emitted by a chimnet could vary from chimney to chimney.
“You could have an enormous amount of CO3 coming out of the chimny and there could be water that has formed on top of that,” he explained.
“And if you look on top, it could be a water vapourer.”
In fact, the authors found that it was the water that is responsible for the water-based smoke in the air.
“These are two very different processes that occur in the combustion process,” Wilson said.
“You have a CO2 combustion and you have water combustion, and the water in a fireplace is a major contributor to the CO2.”
So why does the air in a firehouse have a smoke that smells like rotten eggs?
“We don’t know that yet,” Wilson added.
“We are not sure if it is due to the fact that the air is still warm or because it is still hot,” he told CNN.
“But it has got to be very hot, because it has an impact on the CO 2 production process in the firehouse.”
The research is published in the journal Environmental Research Letters.