Rio more polluted than NY, Paris or London

 　　RIO DE JANEIRO, Sept. 26 (Xinhua) -- Rio de Janeiro has the highest level of air pollution in Brazil, and is more polluted than many other world metropolis¹ like New York, London and Paris, a World Health Organization (WHO) study said Monday.

　　According to the study, which was carried out in 91 countries and regions, the air in Rio's metropolitan² area contains 64 micrograms of fine particulate³ matter per cubic meter, over three times the upper limit set by the WHO, which is 20 micrograms per cubic meter.

　　Despite being larger, having a bigger population and more vehicles, Sao Paulo's metropolitan area has less air pollution, with 38 micrograms of fine particulate matter per cubic meter.

　　According to the WHO, "the largest contributors to urban outdoor air pollution include motor transport, small-scale manufacturers and other industries, burning of biomass and coal for cooking and heating, as well as coal-fired power plants." The organization said that residential⁴ wood and coal burning for heating also help increase air pollution, especially in rural areas in the cold months.

　　The WHO expressed concern over air pollution levels in several cities, as some two million people worldwide die annually⁵ from conditions resulting from air pollution.

　　"Air pollution is a major environmental health issue, and it is vital that we increase efforts to reduce the health burden it creates," said Dr. Maria Neira, WHO's director for Public Health and Environment.

　　According to the study, Ahwaz, Iran, has the most polluted air in the world, with 372 micrograms of fine particulate matter per cubic meter.

1 metropolis   

n.首府；大城市

参考例句：

• Shanghai is a metropolis in China.上海是中国的大都市。
• He was dazzled by the gaiety and splendour of the metropolis.大都市的花花世界使他感到眼花缭乱。

2 metropolitan   

adj.大城市的，大都会的

参考例句：

• Metropolitan buildings become taller than ever.大城市的建筑变得比以前更高。
• Metropolitan residents are used to fast rhythm.大都市的居民习惯于快节奏。

3 particulate   

adj.微小的；n.微粒，粒子

参考例句：

• A special group was organized to dig up the particulate of the case.成立了一个专门小组来查明该案件的各个细节。
• Lungs retain relatively insoluble particulate material.肺脏内留有不溶解的颗粒物质。

4 residential   

adj.提供住宿的；居住的；住宅的

参考例句：

• The mayor inspected the residential section of the city.市长视察了该市的住宅区。
• The residential blocks were integrated with the rest of the college.住宿区与学院其他部分结合在了一起。

5 annually   

adv.一年一次，每年

参考例句：

• Many migratory birds visit this lake annually.许多候鸟每年到这个湖上作短期逗留。
• They celebrate their wedding anniversary annually.他们每年庆祝一番结婚纪念日。