It gets especially bad in the winter when crops are burned in neighboring states and cooler temperatures create smoggy conditions.

在冬季，当邻近各州焚烧秸秆，较低的气温造成雾霾天气时，该市的空气质量变得尤其差。

Sleepy medieval market towns found themselves transformed into smoggy metropolises  by cotton mills and mining.

沉睡的中世纪集镇发现自己因棉纺厂和采矿业而变成了烟雾弥漫的大都市。

He says smoggy weather in many parts of the country is mainly caused by China's extensive development pattern and the unreasonable industrial and energy structures.

他表示，造成我国大部分地区出现雾霾天的主要原因是我国粗放的发展方式以及不合理的产业和能源结构。