背景閱讀：

　　經(jīng)中國環(huán)境監(jiān)測總站會同京津冀及周邊省級環(huán)境監(jiān)測中心預報，受不利氣象條件影響，京津冀及周邊地區(qū)將發(fā)生一次大范圍重污染天氣，此次重污染過程從16日下午開始，將一直持續(xù)至21日，持續(xù)時間長達6日，其間超過20個城市空氣質量可能連續(xù)4天達到重度及以上污染，且可能出現(xiàn)2天以上的嚴重污染。本次重污染過程影響范圍廣、持續(xù)時間長、污染程度重。號稱今冬最重霧霾!

　　While Beijing smothered Monday under a cloud of smog and a reputation for horrible air, other cities in the world quietly vie for the tarnished crown of world's most polluted city.

　　tarnished

　　v.(通常指金屬) (使)失去光澤，(使)變灰暗( tarnish的過去式和過去分詞 ); 玷污，敗壞;

　　例句：

　　His image was tarnished by the savings and loan scandal.

　　他的形象因為那樁儲蓄信貸丑聞而受損。

　　其他：

　　原型： tarnish

　　And this year's winner is: Zabol, Iran.

　　Beijing and much of northeastern China are currently shrouded in a smog red alert, causing some factories to shut down, highways to close and airlines to cancel flights. But the World Health Organization ranks the world's cities based on air pollution, and the worst Chinese city, Xingtai, only ranks ninth in the 2016 list.

　　WHO's ranking, released in May, is based on the amount of PM 2.5 – particle matter smaller than 2.5 microns in diameter common to dust, soot and smoke. PM 2.5 is nasty because it can get stuck in the lungs and cause or aggravate asthma and other long-term health problems.

　　diameter

　　n.直徑，直徑長; 放大率;

　　例句：

　　This hole was a scant. 23 inches in diameter.

　　這個洞眼的直徑只有0.23英寸。

　　其他：

　　復數(shù)：diameters

　　WHO guidelines call for no more than 10 micrograms of PM 2.5 per cubic meter of air. Dusty Zabol averages a whopping 217. Other cities cracking the dubious list's top five include Gwalior, India, at 176, Allahabad, India at 170, Riyadh, Saudi Arabia at 156 and Al Jubail, Saudi Arabia at 152.

　　China chokes on smog so bad that planes can't land

　　Beijing suffered Monday with levels hovering above 200; other Chinese cities have pushed close to 1,000 in recent days.

　　The tide can be turned with effort. The 2015 most-polluted city, New Delhi, slid to 11 in 2016 thanks a crackdown that included bans on the most polluting cars and trucks and fines for for burning trash.

　　crackdown

　　n.壓迫，鎮(zhèn)壓; 打擊，制裁; 強制取締;

　　例句：

　　The EU also staged a crackdown on harmful tax practices, including unequal treatment of residents and non-residents.

　　歐盟還對有害稅收行為進行了打擊，其中包括對居民和非居民的不公平對待。

　　其他：

　　復數(shù)：crackdowns

　　Breathe easier, America. The worst U.S. city didn't crack WHO's top 1,000. Visalia, Calif., checked in at 1,080.