[jschwartzi]

The solution was actually legislation and regulation of the auto industry. The legislature in California and (to some extent) the US realized that particulate pollution and smog were major problems in cities, so they passed laws requiring automakers to install equipment that controls emissions. The OBD and OBD II systems, electronic fuel injection, the catalytic converter, and various other systems are a result of that legislative push.

If they had left it up to the individual, as India has, we would experience similar air quality.

I should add that California has tighter emissions standards than the federal government, and some vehicles will be sold with special emissions control equipment in California. For example, I had a GMC C1500 truck, which shipped with an optional Air Injection Reactor if you bought it in California.

[brianwawok]

In fact my lawn mower has 2 models... California and everywhere else.