Another canary in the coal mine. Similar to massive hurricanes, droughts, floods etc. will smog shutting down cities become the new normal?
Shanghai China: Smog shuts down City, December 6 2013. The cities government issued its most severe health warning as the city's air pollution reached 31 times that of the international standards. From construction workers to school children residents were sent home. Pollution has now surpassed land dispute as the top cause of social unrest in China.