Shanghai issues 'Yellow Alert', days after Beijing's 'Red Alert'

Smog in Chinese metropolis Shanghai hit its highest today, prompting schools to ban outdoor activities and authorities to limit work at construction sites and factories as polluted air spreads around the country. The smog prompted Shanghai authorities to issue a "yellow alert," the third-highest level warning, and to advise elderly, young and sick residents to remain at home, avoid outdoor activity and keep the windows closed.