中国空气污染是由什么造成的?

The Environment Ministry said in January 2012 that the National IV standards would be applied to diesel-engine vehicles from July 2013.
2012年1月环护部说，从2013年7月起柴油车将实行国IV排放标准。

China has other options, such as promoting the scrapping of old vehicles.
中国还有其他选择，比如推进旧车报废。

Last year, the city of Beijing offered financial incentives to car owners to get rid of older cars. But the amounts involved were modest -- up to around 16,000 yuan for larger cars.
去年，北京市提供资金支持以鼓励车主报废旧车。但鼓励额度并不高，报废大中型车最多能享受大约人民币1.6万元的补贴。

Lin Huaibin, manager for China vehicle-sales forecasts at research firm IHS considers such incentives 'a start' toward increasing the scrappage ratio in China, which currently stands at around 3% of total registered vehicles, considerably less than the U.S. rate of around 8%. Mr. Lin said it's 'pretty likely' that other Chinese cities will follow in the steps of Beijing.
研究机构IHS中国汽车销售预测部门负责人林怀滨认为，上述刺激措施朝提高中国车辆报废率迈出了第一步。中国目前报废车辆占登记车辆总数的比例约为3%，远低于美国约8%的报废率。林怀滨说，中国其他城市很有可能会效仿北京的做法。

The latest pollution episode also could see more Chinese cities introduce restrictions on auto purchases.
最近这起污染事件可能会令中国内地更多城市引入车辆限购措施。

Last year, the southern city of Guangzhou and the southwestern city of Guiyang joined Beijing and Shanghai by putting car-ownership restrictions in place that seek to relieve traffic conditions and limit air pollution.
去年，南方城市广州和西南部城市贵阳也加入北京上海的行列，这两个城市将落实车辆限购措施，以缓解交通拥堵的现状，防止空气污染进一步恶化。

It is unclear whether such moves could specifically result in a fall in auto sales. Macquarie's Ms. Lewis said she didn't expect any further restrictions on the purchase of new vehicles as a consequence of the recent pollution problems.
目前还不清楚此举是否会导致汽车销量下降。麦格理证券的刘易斯说，她预计最近一系列污染问题不会导致政府进一步出台新车限购措施。

Beijing had about five million vehicles on the road at the end of 2011 or 260 vehicles per 1,000 people. As of the end of 2011, Guangzhou had 2.33 million vehicles on the road, meaning 180 vehicles per 1,000 people, according to a government-affiliated transportation think tank in the southern Chinese city.
2011年底，北京约有500万辆汽车在路上行驶，平均每千人拥有260辆车。广州一家政府下属的交通运输方面的智库说，截至2011年底，广州有233万辆汽车在路上行驶，这意味着每千人拥有180辆车。

There are more than 800 licensed vehicles for every kilometer of road in Beijing, data from the Beijing government show, compared with 306 vehicles in Hong Kong and 520 vehicles in Shanghai.
北京市政府数据显示，在北京每公里道路上拥有牌照的车辆超过800辆，香港为306辆，上海为520辆。

Globally, about one third of polluting emissions can be attributed to transportation-related sources, said Mr. Dyer of A.T. Kearney. Of this, about one-third is linked to passenger cars, one-third to commercial vehicles and the rest to other forms of transportation including airplanes and ships.
科尔尼的戴加辉说，在全球范围内，大约三分之一的污染排放可以归因为与交通相关的污染源。其中大约有三分之一是乘用车造成的，三分之一是商业车辆，剩下三分之一是包括飞机和轮船在内的其它交通工具。

However, in the case of Beijing about 50% of harmful emissions are caused by transportation sources, he said.
但戴加辉说，就北京的情况而言，约50%的有害气体排放是交通污染源造成的。