A polluted stream which has turned white in Dongchuan district of Kunming, Yunnan province, March 20. According to local media, the source of the pollution is waste water discharged by nearby mining industries.

Farmers dig ditches from a white polluted stream to farm fields for irrigation in Dongchuan district of Kunming, Yunnan province, March 21.

A villager carries buckets of water to be used for drinking from a white polluted stream in Dongchuan district of Kunming, Yunnan province, March 20.

A villager holds two bottles of water, one from the polluted stream, left, and the other normal mineral water, in Dongchuan district of Kunming, Yunnan province, March 21.

A couple wearing a mask and a scarf visits the Bund in front of Pudong Lujiazui financial area on a hazy day in Shanghai on Jan. 16.

Waste gas is discharged into the air by an oil refinery plant in Qingdao city, eastern China's Shandong province, on Jan. 16.

Travel photos are displayed in a photography service shop at the Bund in front of Pudong Lujiazui financial area on a hazy day in Shanghai on Jan. 16. Chinese media said on Monday the government had to take urgent action to tackle air pollution, which has blanketed parts of the country at dangerous levels in recent days, and one newspaper called for a re-think of a "fixation" on economic growth.

Children are put on drips as many of them are diagnosed with respiratory diseases at a provincial children's hospital in Hefei, Anhui province on Jan. 16. Days after choking smog blanketed China's capital, the country's premier-designate added his voice to appeals to curb the toxic haze, but he offered few specifics and said there was no quick fix. Particulate matter with a 2.5 micrometer diameter, known as PM2.5, can cause cardiopulmonary disease, lung cancer and acute respiratory infection, according to the Journal of Toxicology and Environmental Health.

A tourist looks at the Forbidden City as pollution covers the city on Jan. 16 in Beijing.

A Chinese woman covers her mouth as she makes her way along a busy intersection in Wuhan, central China's Hubei province on Monday. The Chinese metropolis of Wuhan was blanketed by thick yellowish cloud, raising fears of pollution among its nine million inhabitants, as air pollution is increasingly acute in major Chinese cities and authorities are frequently accused of underestimating the severity of the problem in urban areas, especially in Beijing.

A thick yellow cloud covers a busy intersection in Wuhan, central China's Hubei province, on Monday.

A woman wears a mask as she walks along a street in front of a Chinese temple during a hazy day in Wuhan, Hubei province on Monday. China's carbon emissions could be nearly 20 percent higher than previously thought, a new analysis of official Chinese data showed on Sunday, suggesting the pace of global climate change could be even faster than currently predicted.

A view of the Oriental Pearl TV Tower, right, and downtown Shanghai seen through the haze on May 15, 2012.

The new China Central Television (CCTV) tower hardly visible as fog covers most of Beijing on Saturday. More than 400 flights to and from Beijing airport, including around 35 international services, were cancelled or delayed due to thick fog and strong air pollution covering the city, which the US embassy own measuring system, said pollution in Beijing had reached the "hazardous" level early March 17, before dropping one notch to "very unhealthy" later.

Vehicles make their way along a highway as fog covers most of Beijing on Saturday.

Passengers wait for their flights as almost 250 flights were cancelled, including some 15 international services, while more than 180 flights were delayed, including about 20 international services at the Beijing Capital International airport as visibility was at less than 200 metres (650 feet), official state news agency Xinhua said, blaming "widespread fog" for the disruption, in Beijing on Saturday.

Tan Liang, a resident of Beijing, prepares to take readings on a PM2.5 detector outside his residential compound in Beijing, China, on Dec. 3, 2011.

Tan Liang carries a PM2.5 detector towards a garbage-burning facility located near his residential compound in Beijing on Dec. 3, 2011.

Wang Qiuxia, right, a volunteer from an environmental group, teaches Cheng Jing, left, how to operate the PM2.5 detector in Beijing on Dec. 7, 2011.