The dangers posed by lead’s carcinogenic toxicity, whether it’s inhaled or absorbed into the bloodstream, have been well-known for decades. Lead is particularly harmful to children during their developmental years. The U.S. Environmental Protection Agency began discussing a total ban on lead in automobile gasoline back in the mid-1980s and outlawed the heavy metal in all fuel sold in the United States nearly 25 years ago, with one exception: aviation gasoline, or avgas.
General aviation’s need for a high-octane fuel to power high-compression piston engines required avgas makers to add tetraethyl lead before delivery to prevent damaging engine knock, or detonation, that could result in engine damage. The higher the octane rating, the better the chances the fuel can be compressed without detonation. The FAA recently estimated that nearly 170,000 aircraft operate today on 100 low lead (LL) fuel, burning 150 to 175 million gallons annually. READ MORE (Popular Mechanics)