Vic Shao
4 min readNov 27, 2018


Was Leaded Gasoline Really a Thing? What Were We Thinking?

My son just reached driving age and he filled up at a gas station for the first time recently. He asked me “what does unleaded gasoline mean?” as he had no idea that lead was a common component in gasoline as recently as the 1980’s. Armed with chemistry knowledge from his high school class, he went on to explain the toxic effects of lead poisoning and associated environmental harms. It’s scientifically proven and commonly accepted today of course, but it took more than 60 years to bring about change. The story of the leaded gasoline is an important reminder of the danger of institutional inertia and why as an industry, transportation electrification is the natural next step.

Lead was first mixed into gasoline in the early 1920’s as an anti-knock additive for internal combustion engines (ICE), boosting performance and fuel efficiency. “Engine knock” happens when premature combustion of the air-gasoline mixture occurs inside the engine cylinder from compression, before the precisely timed moment when the spark plug ignites. It causes early engine failures, not to mention inefficient fuel burn. Adding lead to gasoline was the cheap solution to an otherwise intractable engineering problem.

What we now know about lead poisoning is that it is an insidious affliction that slowly manifests itself over years and causes irreparable harm to the human nervous system and brain development. Studies have shown that children exposed to lead have lower IQ than their peers. There is a statistically significant correlation between the phase-out of lead and the reduction in violent crimes in the 1990’s. There is even speculation that lead poisoning may have played a role in bringing down the Roman Empire. This brings us to the unsung hero of our story, a scientist by the name of Clair (“Pat”) Patterson, who in the 1960’s made it his life’s mission to draw public attention to this lead issue.

The Leaded Crusade

Patterson was a hardcore geologist; he applied uranium-lead half-life decay in rocks to date the age of our solar system and by extension, the age of Earth itself. Early on, the problem he kept running into was sample contamination. Since he was measuring trace amounts of lead in rocks, any atmospheric pollution would skew the results. Patterson ended up building the first clean room from scratch in the early 1950’s at Caltech, and brought in ocean sediment and ice-core samples from around the world. What he learned was truly distressing. The amount of lead dispersed into the environment in the 1950’s and 60’s was 80 times higher than in the geologic past. Lead was everywhere — in the air, water, soil, and in our food. In an age before Twitter and hype, Patterson decided to go to war against the entrenched establishment armed with scientific facts and painstakingly researched data.

As one can imagine, the petrochemical industry fought back hard, not only with its lobbying power but also through its own panel of scientific experts. Patterson was ostracized by the research community, including the US Public Health Service and the National Research Council. Only through the use of his clean room did he ultimately prove what was the historic norm for lead levels compared to what was occurring during his day. This is at a time when science still prevailed over “fake news”, and the federal government made actual decisions based on facts and evidence. The EPA made the ruling in 1985 to phase out lead in gasoline. The effects were felt almost immediately; a 1994 study indicated the concentration of lead in the bloodstream of the U.S. population had dropped 78% from 1976 to 1991. Patterson’s brave (and still under-appreciated) crusade benefitted the health and well-being of entire generations around the country.

92% of transportation is powered by petroleum

Let’s fast forward to the transportation landscape of today. We have overwhelming scientific evidence of climate change induced by deforestation, coal, and fossil fuels. We know that in the U.S., the transportation sector consumes 29% of all categories of energy use, and 92% of transportation is powered by petroleum. The underlying rationale for leaded gasoline from 1920’s — 1980’s was premised on the economics of cheap lead. Eliminating it would reduce fuel economy, drive up transportation costs, and harm the engines in our cars! Why change — easier to just stay the course!

But wouldn’t you know it, just the opposite happened over the past 30 years. In the era of unleaded gasoline, fuel economy actually went up. Engines last longer. Our ability to innovate and overcome engineering challenges has prevailed once again.

The environmental challenges facing us today are more dire than ever. We now have the technology to wean off fossil fuel altogether, replaced with 100% clean and renewable electric energy. In the process, we will create new jobs and even dramatically reduce the overall cost of transportation. What is stopping us right now is simply the fear of making a change — just like with leaded gasoline 30 years ago. I hope to one day have my grandchildren ask me the question, in a similarly quizzical expression as my son’s, “did you REALLY used to burn dead plants and dinosaurs for fuel?”