It’s hard not to feel better about life, wandering around a neat and tidy southern Californian city with the sun shining. But I can guarantee that you’ll also breath much more easily in this state.

Since the late 1960s, the California Air Resources Board (CARB) has been at the forefront of driving down engine pollution.

image It was California that demanded 1975-model year cars achieve massive reductions in pollution. Car makers said they couldn’t meet the targets, but eventually did by detuning engines and embracing the catalytic converter.

Honda, however, met the regulations with its landmark Civic CVCC engine, which was so clean it didn’t even need a cat.

Moreover, CARB effectively banned diesel cars in 2000 when they decided that ‘toxic’ particulates were a serious threat to human health.

Only Mercedes BlueTec engines have recently managed to meet the super-tight Californian diesel emissions regulations.

No surprise then, that California uses buses powered by super-clean Compressed Natural Gas.

UK politicians, particularly Ken Livingstone,­ make a huge song and dance about micro reductions in CO2, while happily gassing people with belching diesel buses and cabs.