City in the sky

It is a dystopian world where everyone ignored climate change and pollution so the earth's surface became very contaminated. The rich tried to get as far away as possible from the ground, many even left to look for a better planet to live on. Those who couldn't afford to leave stayed but started building away from the contamination, away from the earth's surface. So the richer you were the higher you would live, the poor had to live on the polluted ground with no real choice.