While we're on the subject of polluted cities, let's consider China. Sure, it boasts two listings on the top ten list below. But this Saturday, China (like all of China) is attempting to confront that ever worsening situation. More than 100 cities will participate in a nation-wide "no drive day" in an effort to raise awareness and embrace public transit. Sure, it's something of an empty, symbolic gesture. Then again, that's a whole lot of not driving.