In Europe, getting away from population density is not really possible. They have limited urban sprawl with restrictions to avoid using up all their available farm land, so most people have to be city dwellers or farmers.
Much has been written about Europe's pollution and the damage it does to peoples' health and even to historic monuments. Although some of the concerns are due to vehicles, most had to do with dirty industries and power generation from facilities that use outdated equipment. As one segment gets cleaned up focus is now on another, but there are diminishing returns on expenditures as the standards continue to tighten.
