At the other end of the list are cities in Canada and the United States, which benefit from lower population density, favorable climates and stricter airpollutionregulation.
污染最轻的是美国和加拿大的城市，原因是它们的人口密度低，气候怡人，并且空气污染管理规定非常严格。
2
At the other end of the list are cities in Canada and the United States, which benefit from lower population density, favorable climates and stricter airpollutionregulation.