Over crowding!
Ten times the population, squeezed into far less hectares of land.
If people would stop trying to jam a million, or 25 million people into as tiny space as possible, and instead get out into the country, their lifestyle would be so much better.
I went for a run this morning with my girlfriend and dogs...we ran down 4 kms of road, and back, saw 1 car with 2 people in it the whole time. If you do live in a city, go out for a hike, fishing, dirt bike ride on bush trails, just get out and enjoy the fresh air, and away from the pollution of the big city...and by pollution I also mean noise pollution. Vancouverites, go enjoy a hike on the Lions, or throw your boat in the Pacific ocean and enjoy a spin.