HOW THE US HAS TACKLED AIR POLLUTION
The first real attempts to clean up tailpipe pollution and the resulting smog came in the late 1960s in California.
After a famous Los Angeles smog incident in 1943, it was established in the early 1950s that exhaust gases and LA’S topography had combined to cause the problem.
California was the first to establish laws to clean up the atmosphere, which governor Ronald Reagan signed to create the State Air Resources Board and the 1967 Federal Air Quality Act.
Classic car enthusiasts might remember the 1975 model year was a turning point for emissions control, when European car makers had to throttle their engines to pass US pollution laws.
For example, the Opel GT coupé (which was a popular car in California at the time) had a 120bhp engine, but when it was ‘smogged’ for 1975, it fell to just 75bhp.
The US kept the pressure on for another 20 years, leading to the production of petrol and CNG cars with such small pollution footprints that they were categorised as Super Low Emissions Vehicles, emitting 90% less tailpipe pollution than standard petrol vehicles.
Attempts to regulate fuel economy began at state level in 2007, before the Barack Obama administration brought CO2 emissions under national law in 2012.