Leaded gasoline for cars and trucks is gone worldwide. Algeria, the last country still selling it, stopped in July 2021. But leaded fuel hasn’t disappeared entirely. It remains in use in piston-engine aircraft across the United States and globally, and in certain motorsport categories. These are the last holdouts, and efforts are underway to phase them out too.
How Leaded Gas Disappeared From Roads
The United States began phasing out leaded gasoline in the mid-1970s after research linked airborne lead to serious health problems, particularly in children. Most developed nations followed over the next two decades. By the early 2000s, a UNEP-led initiative called the Partnership for Clean Fuels and Vehicles was pressuring the remaining holdouts through a combination of science, public education, policy work, and, as UNEP put it, shame.
It worked. Country after country switched. By 2020, Algeria was the only nation on Earth where drivers could still buy leaded petrol. Its state-owned oil company stopped producing the fuel in late 2020, and over the following months Algeria decontaminated its storage facilities and distribution networks. Service stations confirmed they were no longer selling leaded petrol in July 2021, roughly 99 years after the fuel was invented.
The health impact of this global phase-out has been enormous. In the United States, the median blood lead level in children ages 1 to 5 dropped 96% between the late 1970s and 2020, falling from 15.0 micrograms per deciliter to just 0.6. Removing lead from gasoline was the single biggest driver of that decline.
Leaded Fuel in Aviation
The largest remaining use of leaded fuel is in small piston-engine aircraft. These planes, which include most single-engine propeller aircraft used for private flying, flight training, crop dusting, and air taxi services, run on a fuel called 100LL (100 octane, low lead). Almost all aviation gasoline sold in the U.S. market today is 100LL. About 167,000 aircraft in the United States and 230,000 worldwide depend on it.
These aircraft need high-octane fuel to prevent engine knock, and lead has historically been the cheapest and most effective octane booster available. Unlike car engines, which were redesigned to run on unleaded fuel decades ago, many piston aircraft engines were never re-engineered. Switching fuels isn’t as simple as pulling up to a different pump. The wrong fuel can cause engine failure in flight.
The scale of lead pollution from aviation is significant. In 2017, piston-engine aircraft emitted roughly 470 tons of lead into the air in the United States alone, making them the single largest source of airborne lead in the country. Aircraft engines have accounted for more than 50% of all lead emissions to air in the U.S. since 2008. In October 2023, the EPA issued a formal finding that lead emissions from these aircraft endanger public health and welfare, a legal step that opens the door to regulation under the Clean Air Act.
The Push to Eliminate Leaded Avgas
The FAA and aviation industry partners have set a goal of eliminating leaded aviation fuel by the end of 2030 through an initiative called EAGLE (Eliminate Aviation Gasoline Lead Emissions). The challenge is certifying an unleaded replacement that works safely across the full range of piston aircraft engines. Several candidate fuels are in development, and the FAA is working to expand approvals so that aircraft owners can legally make the switch.
This isn’t a simple timeline to meet. Every aircraft engine and airframe combination needs specific authorization to use a new fuel, which means thousands of individual approvals. Fuel producers also need to scale up manufacturing and distribution infrastructure to replace 100LL at airports nationwide. Still, the 2030 target represents the first firm deadline the industry has committed to.
Leaded Fuel in Motorsports
A handful of racing organizations still require or permit leaded fuel. The National Hot Rod Association (NHRA) and the International Hot Rod Association (IHRA) both use leaded racing gasoline. These fuels contain higher lead concentrations than old road gasoline ever did, because drag racing and other high-performance applications demand extreme octane ratings.
Most major racing series, however, have already moved on. NASCAR switched to unleaded fuel at the start of the 2007 season. Formula One and IndyCar also run on unleaded formulations. The trend is clearly toward elimination, but leaded racing fuel remains available for purchase and is still used in certain competitive categories and by hobbyist racers running older engines.
Why Lead Was Added in the First Place
Lead in the form of tetraethyl lead was added to gasoline starting in 1923 to solve a specific engineering problem: engine knock. When fuel ignites unevenly inside a cylinder, it creates a knocking or pinging sound and can damage the engine over time. Adding small amounts of lead raised the fuel’s octane rating, allowing it to burn smoothly under higher compression. It was cheap, effective, and catastrophic for public health.
Lead is a potent neurotoxin with no safe level of exposure. Burning leaded gasoline released fine lead particles into the air, where they were inhaled or settled into soil and water. Decades of exposure affected virtually every person alive during the leaded gas era, with children bearing the worst consequences: reduced IQ, learning disabilities, and behavioral problems. Some researchers estimate that leaded gasoline exposure lowered the collective IQ of Americans born before the mid-1980s by several points on average.
Modern unleaded gasoline achieves high octane ratings through refining techniques and alternative additives like ethanol. For road vehicles, the engineering problem was solved long ago. Aviation is the last sector where a practical, widely certified unleaded replacement is still catching up.