The pollution over the past few weeks has reopened the question of whether improvements seen earlier in the year were due to economic factors, or the top-down diktats from Beijing.
过去几个星期的污染已重新点燃这样一个问题：今年早些时候看到的空气改善是由于经济因素，还是源于北京发出的自上而下的政令？
The sudden surge in pollution since September came after an unusually clear spring and summer for Beijingers.Steel mills in nearby Tangshan, the heart of the Chinese steel industry, shut this spring to ensure clear air for a horticultural show.The result was that steel mills in the Yangtze Valley raised production amid a corresponding increase in haze in Shanghai.
自9月以来污染突然加剧之前，北京市民度过了一个异常清新的春天和夏天。距离北京不远的中国钢铁工业中心唐山的钢铁厂在今年春天关闭，以便为一个园艺展览保障清新空气。其结果是长江流域的钢铁厂加大马力生产，而上海的雾霾出现相应增加。
