Nearly every fuel, when consumed, emits various substances into the air. These fuel emissions, especially when they come from fossil fuels, can be very harmful to the environment and to the lives of humans, animals, and plants. When a fossil fuel is burned, it tends to release a significant amount of carbon dioxide into the air; it can also release other harmful substances such as sulfur dioxide or carbon monoxide. Fossil fuels are burned around the world for countless purposes which range from powering automobiles and airplanes to providing electrical energy. The mass burning of fossil fuels releases massive quantities of fuel emissions which can have wide-ranging effects on many different things.
One of the major concerns people have about fuel emissions is the effect that such emissions have on the environment. Many of the gases released through the burning of fuels, such as carbon dioxide, are greenhouse gases that cause the greenhouse effect and contribute to global warming. Carbon dioxide is one of the primary fuel emissions resulting from the burning of fossil fuels, so the effect on the environment is significant. Fossil fuels are primarily hydrocarbons, so burning them breaks the bonds between carbon and hydrogen, carbon atoms bond to oxygen, and carbon dioxide is released.
Carbon monoxide emissions are another dangerous type of fuel emissions, but carbon monoxide emissions are more directly harmful to humans. Carbon monoxide emissions result from the incomplete combustion of fossil fuels, which happens in the chemical processes in automobiles. As a result, automobiles are equipped with catalytic converters that oxidize carbon monoxide into carbon dioxide, which is less harmful directly. Catalytic converters also cause other chemical reactions which make some of the other products of burning fossil fuels somewhat less dangerous.
Fuel emissions lead to a dangerous and harmful process known as acid rain in which chemicals released into the atmosphere through the burning of fossil fuels return to the ground in the form of acidic precipitation. This can be very harmful to plants, water supplies, aquatic creatures, and some man-made objects. Sulfur dioxide is the compound that is most commonly associated with acid rain; it dissolves in the moisture of the atmosphere and becomes sulphurous acid. Nitrogen oxides can also contribute to acid rain and are common in car exhausts. Lead compounds can also be released by the burning of fossil fuels; in high concentrations, these fuel emissions can lead to impairment in children.