Buildings in the western Japanese city of Osaka, some 2,250 kilometers (1,400 miles) southeast of Beijing, are shrouded in dense smog Wednesday, February 26, 2014 a day after parts of northern China suffered a sixth straight day of severe pollution. The readings of particulate matter known as PM2.5, a key measure of pollution reached 104 micrograms per cubic meter in Osaka in the morning. The World Health Organization considers 25 micrograms a safe level. (Photo by AP Photo/Kyodo News)

A general view of the pollution covered Beijing CBD on February 25, 2014 in Beijing, China. The air pollution has caused an increase in the number of people seeking hospital treatment for respiratory problems and the public are asked to avoid outdoor activities. (Photo by Lintao Zhang/Getty Images)

A couple watches the Seoul skyline covered with a thick haze at Seoul Tower's observation deck in Seoul, South Korea, Wednesday, February 26, 2014. The Seoul metropolitan government issued a dust warning, urging people to stay indoors. (Photo by Ahn Young-joon/AP Photo)

Children walk back home after school on a severely polluted day in Shijiazhuang, in northern China's Hebei province, Wednesday, February 26, 2014. (Photo by Alexander F. Yuan/AP Photo)

Vehicles clog a main highway during a sixth straight day of severe pollution in Beijing Tuesday, February 25, 2014. Hazardous white pollution hid much of Beijing's skyline Tuesday, despite announced closures or production cuts at 147 of the city's industrial plants. Chinese characters on board reads: “Smog weather, reduce going outside”. (Photo by Ng Han Guan/AP Photo)

A watchdog stands in front of a wall with a mosaic scenic painting at a cement plant on a severely polluted day in Shijiazhuang, in northern China's Hebei province, Wednesday, February 26, 2014. The meteorological center said moderate or severe pollution had persisted in northern China since Thursday, and that it was particularly serious in Beijing and its surrounding area. It forecast that the pollution would continue in parts of eastern, northern and central China until Wednesday evening, when precipitation and wind should help to disperse it. (Photo by Alexander F. Yuan/AP Photo)

People are seen inside a residential apartment building as city skyline shrouded with heavy haze in Beijing Wednesday, February 26, 2014. Beijing remained cloaked in hazardous white pollution hiding much of its skyline Wednesday, despite the announced closures or production cuts at 147 of the city's industrial plants. (Photo by Andy Wong/AP Photo)

A man and a car travelling on a road are obscured in heavy haze on a severely polluted day in Pingshan county of Shijiazhuang, in northern China's Hebei province, Wednesday, February 26, 2014. Chinese President Xi Jinping braved Beijing's choking smog Tuesday, making an unannounced visit to a trendy alley and sitting with residents in his latest public relations effort to be seen as a man of the people. (Photo by Alexander F. Yuan/AP Photo)

Vehicles clog a highway during a hazy day in Beijing, China, Wednesday, February 26, 2014. Beijing remained cloaked in hazardous white pollution hiding much of its skyline Wednesday, despite the announced closures or production cuts at 147 of the city's industrial plants. (Photo by Ng Han Guan/AP Photo)

Paramilitary policemen stand ready to march across Tiananmen Square on a severely polluted day in Beijing, China, Tuesday, February 25, 2014. Pollution across a large swath of northern China worsened on Tuesday. (Photo by Alexander F. Yuan/AP Photo)

Pedestrians cross an overhead bridge as vehicles clog a main highway during a sixth straight day of severe pollution in Beijing Tuesday, February 25, 2014. Hazardous white pollution hid much of Beijing's skyline Tuesday, despite announced closures or production cuts at 147 of the city's industrial plants. (Photo by Ng Han Guan/AP Photo)

In this photo taken Sunday February 23, 2014, residents barbecue along the river bank during a hazy day in southwest China's Chongqing municipality. Xinhua said that almost all provinces in central and east China have had serious air pollution since Friday, and that Beijing and five provinces in northern and eastern China had reported “severe smog”. (Photo by AP Photo)

Chinese women wearing masks cross the road near the headquarters of the China Central Television headquarters during a hazy day in Beijing, China, Wednesday, February 26, 2014. (Photo by Ng Han Guan/AP Photo)

A combination picture shows Beijing's hazy sky (L) on February 24, 2014 and clear sky on February 27, 2014, from the top of Jingshan Park near the Forbidden City. China's environment ministry has vowed to “harshly punish” factories and power plants that contributed to a hazardous smog which enveloped much of Northern China, official state media reported on Wednesday. (Photo by Kim Kyung-Hoon/Reuters)

Tourists visit Jingshan Hill before the Forbidden City as heavy air pollution continues to shroud Beijing on February 26, 2014. Beijing's official reading for PM 2.5, small airborne particles which easily penetrate the lungs and have been linked to hundreds of thousands of premature deaths, stood at 501 micrograms per cubic metre. (Photo by Mark Ralston/AFP Photo)