1967

Automotive Emission Controls

In 1960, in a big US city like Los Angeles, there are several things we would be able to detect: 1) a brown layer of smog visible at the horizon, 2) a layer of lead developing in the topsoil (fallout from leaded gasoline), 3) serious particulate pollution in the air, and 4) ground-level ozone.

Public outcry, combined with the Federal Air Quality Act of 1967, led to a series of engineering advancements that cleaned up car emissions and made our cities breathable again.

The first improvement was positive crankcase ventilation, which was instituted in 1961. This is a simple system that sucks fumes out of a car’s engine and burns them rather than letting them float into the air. This matters because unburned fuel and oil fumes combine with sunlight to create smog.

The next big change was the catalytic converter, combined with unleaded gasoline. The first catalytic converters in 1975 burned off carbon monoxide and unburned gasoline in the exhaust. Later models also eliminated nitrogen oxides. Engineers came up with an innovative, long-lasting ceramic honeycomb approach to bring the exhaust gases in contact with catalyst metals like platinum. Petroleum engineers had to improve refineries and techniques to create gasoline that did not need tetraethyl lead to artificially boost the octane rating.

Another trick that engineers devised is called exhaust gas recirculation. Exhaust contains no oxygen, so it takes up space if sent into the cylinders. Therefore it lowers the temperatures in the cylinder and reduces nitrogen oxides.

Finally there is the gas tank. When a car sits in a parking space, the gasoline in the tank evaporates. Normally these hydrocarbons would float into the air to create smog as the tank vents. Engineers developed canisters filled with carbon granules to absorb gasoline vapors, and sealed gasoline systems.

By combining all of these techniques, engineers radically reduced the lead, hydrocarbons, nitrogen oxides, and carbon monoxide coming out of each automobile on the road. The air in America has been getting cleaner ever since, even with the growing number of cars.

SEE ALSO Oil Well (1859), Wamsutta Oil Refinery (1861), Prius Hybrid Car (1997).

Innovations in automobile transport changed the world as we knew it, but also gave rise to the need for clean air standards.