Buying leaded gasoline nowadays is a rare occurrence since its progressive ban from the United States and other countries. This type of gasoline was originally liquid gasoline, or petrol as it is known in other parts of the world, containing an additive of the chemical element in the form of tetraethyl lead. It was widely adapted for usage in the 1920s, which helped along the development of higher compression engines and boosted octane ratings.
Gasoline generally is consumed as an energy fuel in internal combustion engines, making its environment highly compressed. To increase octane levels, hydrocarbon mixed with benzene or iso-octane is added in. These are the hydrocarbon-containing fuels that would eventually be expelled as greenhouse gases into the atmosphere. Additives were necessary, however, to reduce carbon buildup in internal engines, improve the combustion rate, and facilitate an easier engine ignition in cold weather.
It used to be that before the addition of lead, gasoline tended to pre-ignite or detonate, causing a metallic 'pinging' sound, a situation called engine-knocking, that damaged the engine. Gasoline containing tetraethyl lead changed that. Not only did it withstand higher compression environments, they also lubricated the inside and valves of the engine, protecting the valve seats from erosion.
Qualms about leaded gasoline began with the environmentalists and health professionals. Apparently, the gasoline was incompatible with catalytic converters installed in many on-road vehicles being driven. Catalytic converters are devices used to reduce the toxicity levels of automobile emissions. They are, however, ineffective in the presence of lead due to a chemical alteration that results from their interaction. The Environmental Protection Agency (EPA) stepped in quickly to regulate amounts of auto exhaust, leading to the general disapproval of using gasoline of this type.
Moreover, health professionals determined that consumption of lead products, including leaded gasoline, correlated with the amount of lead found in the human bloodstream. This can cause lead poisoning, a condition that primarily causes neurological damage, gastrointestinal discomfort, and cognitive impairment in children.
The movement in gasoline components has now replaced lead compounds with other appropriate substitutes. Additives now include aromatic hydrocarbons, ethers, and the alcohols ethanol and methanol. In lieu of lead's lubricating properties, auto shops now sell lead substitute products to achieve the same effect.
Since the Clean Air Act was implemented on 1 January 1996, the sale of leaded fuel has been banned for on-the-road vehicles in the United States, with possession or usage subject to high fines. Other countries have been following this example. Leaded gasoline for other uses including racing cars, marine engines, and farming equipment, will be prohibited starting in the year 2008.