Tetraethyl lead (TEL) is a lead compound that was commonly used as an additive in gasoline to increase its octane rating and reduce the risk of engine knocking or detonation. Engine knocking occurs when the air-fuel mixture in the engine’s cylinders ignites prematurely, causing inefficient combustion and potentially damaging the engine.
TEL was highly effective in improving the octane rating of gasoline, with just one gram of lead increasing the octane level of one gallon of gasoline by about 6 numbers. This allowed engines to operate more efficiently at higher compression ratios without experiencing knocking.
However, due to the recognized health hazards associated with lead exposure, particularly in the form of airborne emissions from vehicles, the Environmental Protection Agency (EPA) has phased down the use of lead in gasoline. Lead has been prohibited in highway vehicle gasoline in the United States since January 1, 1996. This transition to lead-free gasoline has led to significant improvements in air quality and public health.
See
- Lead free