Shanghai again chokes under 'severe' pollution

Passengers hire taxis amid heavy smog outside Shanghai Hongqiao International Airport on the evening of Dec 5, 2013. Air Quality Index (AQI), which measure PM2.5 particulates, topped 400 on Friday morning in Shanghai, meaning the city was "severely polluted"- the highest level on the air pollution scale - for the second time in a week. [Photo/icpress.cn]