Butane is a type of flammable gas called a hydrocarbon. It is made of four carbon and six hydrogen atoms. When it burns, butane combines with oxygen, releasing heat in the reaction that can be used in lighters, stoves and other heating applications. Although the products of clean butane production are fairly harmless, butane rarely burns cleanly. A butane fire with an orange flame is not getting enough oxygen to combust completely and, as a result, is releasing several trace pollutants.
It may sound strange, but water is one of the two main ingredients released when butane burns. In combustion, the hydrogen-carbon bonds split and the hydrogen reacts with oxygen in the environment, creating H20 or water. Generally, you will not notice this water since it is carried away from the butane fire as steam.
The carbon in butane also reacts with oxygen during combustion. In a perfect butane fire, all of the carbon is turned into carbon dioxide or CO2. CO2 is a common part of the earth's environment. According to CO2 Now, CO2 concentration is just less than 400 parts per million, or 0.04 per cent of the earth's atmosphere. It is a waste product of animal respiration and is used by plants as part of the process of photosynthesis.
When there is not enough oxygen available for complete combustion, some of the carbon turns into carbon monoxide or CO. Carbon monoxide is a common product of incomplete combustion and is released by other fuels such as gasoline, wood, propane and charcoal as well. In sufficiently high concentrations, carbon monoxide is a deadly gas that can cause asphyxiation and death. A lighter isn't a danger, but stoves that burn butane, propane or other fuels should be used in large, well-ventilated rooms.
Some of the carbon in burning butane will not combine with oxygen at all. Instead it will form carbon particles called soot. Soot is another common product of incomplete combustion. It can damage the lungs and contribute to an array of health problems. Fortunately, a well-maintained butane burner does not produce very much soot, but it is still a good idea to ventilate any room where the gas is being burnt.