Yes, avgas is leaded. The standard aviation gasoline used by piston-engine aircraft, known as 100LL (100 octane “low lead”), contains up to 2.12 grams of lead per gallon. This makes it the last leaded fuel sold legally in the United States and most of the world. Leaded gasoline for cars was banned decades ago, but aviation held on because of the unique demands of aircraft engines.
Why Avgas Still Contains Lead
The lead in avgas comes from a compound called tetraethyllead, or TEL. In small quantities, TEL is extremely effective at boosting a fuel’s octane rating, which is a measure of how well fuel resists uncontrolled ignition (called “knock” or detonation) inside an engine’s combustion chamber.
This matters for aviation more than it ever did for cars. High-performance piston aircraft engines operate at high compression ratios and generate enormous power relative to their size. If the fuel’s octane is too low, detonation can destroy pistons and other internal components, potentially causing engine failure in flight. The FAA considers this a direct safety issue: without TEL, the octane levels in current avgas formulations would be too low for many of these engines to operate safely.
Health Risks Near Airports
Piston-engine aircraft are now the single largest source of lead emissions to the air in the United States. Every gallon of 100LL burned sends lead particles into the atmosphere, and those particles concentrate around airports where small planes take off and land.
A study published in Environmental Health Perspectives examined blood lead levels in children living near general aviation airports. Children within 500 meters (about a third of a mile) of an airport had blood lead levels 4.4% higher than children living farther away. The effect decreased with distance but remained statistically significant out to 1,500 meters (roughly a mile). A separate study at Santa Monica Airport in California found that lead levels in the surrounding area dropped to normal background levels at about 1 kilometer from the runways.
There is no safe level of lead exposure for children. Even small increases in blood lead are associated with lower IQ, attention problems, and behavioral issues. In October 2023, the EPA issued a formal “endangerment finding,” officially concluding that lead emissions from aircraft engines burning leaded fuel cause air pollution that endangers public health. That finding triggers a legal obligation for the EPA to eventually set emission standards for these engines under the Clean Air Act.
The Push to Go Unleaded by 2030
The aviation industry and federal government are actively working to eliminate leaded avgas. In 2022, the FAA partnered with industry groups and the American Petroleum Institute to launch the EAGLE initiative (Eliminate Aviation Gasoline Lead Emissions), with a target of ending leaded fuel use in piston aircraft by December 2030. For Alaska, where general aviation is especially critical for transportation, the deadline extends to 2032.
The transition plan involves a phased approach: fuel suppliers and airports will switch to unleaded alternatives, aircraft owners will complete any necessary modifications, and 100LL will be fully consumed or phased out of the supply chain. The FAA has already approved at least two unleaded fuel options through supplemental type certificates. In September 2022, a 100-octane unleaded fuel called G100UL received approval for use across a broad range of general aviation aircraft. In September 2024, a second high-octane unleaded fuel called 100R was approved for certain Cessna 172 models.
The challenge is scaling production and distribution of these fuels while ensuring every aircraft type in the fleet can safely use them. Some lower-performance engines can already run on unleaded automotive-style fuels, but high-compression engines need a true 100-octane replacement before they can stop using 100LL.
What’s Happening Internationally
The shift away from leaded avgas is global. The European Union set a sunset date of May 1, 2025 for TEL, the lead additive required to make leaded avgas. As of late 2023, no applications had been filed to extend authorization for TEL use beyond that date in EU countries. TEL is banned worldwide for use in vehicle fuel; aviation remains the sole exception.
Australia and other countries are also exploring accelerated timelines, partly because as major markets like the U.S. and EU move away from leaded avgas, the global supply of TEL itself will shrink, making it harder and more expensive for remaining users to source leaded fuel. The practical reality is that leaded avgas is approaching the end of its life worldwide, driven by both regulation and the disappearing supply chain for its key ingredient.