美国空气最清新的城市

Bismarck, N.D.
Population: 106,286
北达科他州俾斯麦
人口：10 6286

Bismarck has some of the lowest year-round particulate levels of all U.S. cities (it comes in at number 11) and ozone levels below what is considered dangerous.
俾斯麦是美国所有整年微粒物质水平最低的城市之一，而且该城市的臭氧含量也属于安全水平。

North Dakota’s capital is protected from pollutants due to a relatively remote location and the fact that it’s not downwind of other cities. Although its winters make it one of the coldest U.S. cities, the low temperatures keep ozone at bay.
北达科他州首府不受污染物的破坏是由于它相对偏远的位置，还有它不处于其它城市的下风区的事实。尽管这样使它冬天成为美国最冷的城市，但是低温也预防臭氧的危害。

Its citizens care also helped establish the Bismarck Tobacco Free Coalition to promote a smoke-free environment.
该市市民也积极帮助建立无烟联盟促进无烟环境。