9.3

• Combustion of fuels is a major source of atmospheric pollutants.
• Most fuels, including coal, contain carbon and/or hydrogen and may also contain some sulfur.
• The gases released into the atmosphere when a fuel burns may include carbon dioxide, water (vapour), carbon monoxide, and oxides of nitrogen (which are formed at high temperatures).
• Solid particles and unburned hydrocarbons may also be released, forming particulates in the atmosphere.
• If there’s not enough oxygen, some of the fuel doesn’t burn – this is partial/ incomplete combustion.
• During combustion, the carbon and hydrogen in the fuels are oxidised to form carbon dioxide and water.
• Carbon monoxide is a toxic gas which is colourless and odourless, making it difficult to detect.
• Sulfur dioxide and oxides of nitrogen cause acid rain and respiratory problems in humans.
• Particulates cause global dimming and human health problems.