Dense fog shrouds east and north China

People cycle through dense fog in the port city of Tianjin in North China, Nov 28, 2011. The fog piled up since midnight on Monday and as of 8 am, all flights were delayed and most of the expressways toll stations are closed because of the heavy fog. [Photo/Xinhua]

Cars travel through heavy fog covering the port city of Tianjin, Nov 28, 2011. [Photo/Xinhua]