The gas produced by combustion is primarily carbon dioxide (CO2). During the combustion process, organic materials, such as fossil fuels, react with oxygen, leading to the release of energy in the form of heat and light. This reaction produces various byproducts, including carbon dioxide, water vapor, and if the combustion is incomplete, carbon monoxide (CO) and particulate matter. The release of carbon dioxide into the atmosphere contributes to greenhouse gas emissions, which are a significant factor in climate change and global warming.