Photos of Beijing, home to 21.7 million residents, show skyscrapers and cars shrouded in thick fog, with air quality indices rated “dangerous” and authorities advising residents to stay in the interior.
Many travelers continued to struggle against the elements, however, walking and pedaling with strong, sandy winds. Visibility was so poor in some parts of the city that drivers had to turn on the headlights even halfway through the day.
“In some places, there are strong sandstorms with visibility below 500 meters (1,640 feet),” the China Meteorological Administration said in a statement Monday. “This is also the strongest dust and sand climate affecting China in nearly ten years.”
Air quality in Beijing was already poor, due to high levels of pollution. When the sandstorm hit, the city’s air quality fell to dangerous levels, according to the World Air Quality Index.
The index measures the concentration of different pollutants in the air, the most important being PM 2.5. This harmful microscopic particle has a diameter of less than 2.5 micrometers and is considered particularly dangerous, as it can lodge deep in the lungs and pass to other organs and the bloodstream.
Beijing on Monday measured a maximum of 655 micrograms per cubic meter. The World Health Organization considers anything over 25 years old to be unsafe.
From Mongolia, the sandstorm gradually shifted south. Beijing saw concentrations of the largest PM 10 particles exceed 8,100 micrograms per cubic meter according to the city’s environmental monitoring center, prompting the Central Meteorological Observatory to issue a yellow alert for sandstorms, the second level in a four-color weather warning system.
Authorities advised citizens to go outside if possible, and the Beijing Municipal Education Commission on Monday called on schools and education committees to suspend outdoor activities.
But sandstorms have abated drastically; the annual number of days impacted by the sandstorm in Beijing fell from a high of 26 in the 1950s to just three days after 2010, according to Xinhua.
Sandstorms have also affected northern Hebei and Shanxi provinces, western Gansu and central and western Inner Mongolia. Monday, Xinhua said. Other parts of the country, including northern Xinjiang, are experiencing high levels of wind gusts. Sandstorms are expected to last until Tuesday.
Mongolia, located in northern mainland China, is experiencing strong cyclones, the weather administration said. Mongolian sand and dust have shifted east and south over northern regions of China, caused by high cold pressure at the back of the cyclone.