A thick haze extended from the mainland over the Sea of Japan in late February, 2014. From mid-February, a temperature inversion trapped pollution near the ground across the region, allowing air pollution to reach hazardous levels. On February 24 and 25, the China Meteorological Administration issued an orange alert of air quality. Visibility was below 2,000 meters (1.2 miles) and it was recommended that people stay indoors or wear a mask while outdoors in the North China Plain, including Beijing.
The haze obscured views of the Earth from space. In this true-color image, captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite on February 25, much of the Sea of Japan is completely masked by the gray pall that stretches from mainland (China, inland, Russia on the coastal north, and North Korea on the southern coast) to Japan in the east. Bright white clouds cover northern Japan. The haze clears in the northern Sea of Japan, allowing a comparison between the near-clear-sky view of the blue waters in that area with the haze-covered view in the south.