Chai Jing, former presenter and journalist with China Central Television, presents a self-funded documentary about smog in Beijing, Feb 28, 2015. [Photo/CFP]

2. Air

China's environment watchdog issued its most comprehensive and toughest plan in July 2013 to control and in some regions reduce air pollution by the year 2017, setting stricter limits on the levels of PM 2.5 particles.

The Air Pollution Prevention and Control Action Plan (2013-17) is backed by 1,700 billion yuan ($277 billion) in total investments from the central government.

The plan specifically targets North China, particularly Beijing, Tianjin and Hebei province. The plan's goal by 2017 is for a 25 percent reduction in air emissions from 2012 levels in that region.

The smog problem has never received so much attention.

In March a privately sponsored documentary on smog, Under the Dome, went viral online in China. It was viewed more than 300 million times within five days.

Ministry of Environment Protection statistics show a big drop in PM 2.5 readings and polluted days in a year since the regulations were put in action. Factories with illegal heavy pollution have been shut down and traffic controls practiced more often. Electric vehicles are promoted r amid the anti-pollution environment. Stations have also been built in more than 160 cities to monitor smog levels.