The unusually 'heavy fog' that has been lingering over Beijing since the weekend is actually smog. This is based on the air quality index readings from the US Embassy in China. The smog is so dense that visibility drops to about 30 to 60 feet. It's been grounding flights and bringing traffic to a crawl.




On Sunday, the Beijing Meteorological Center gave a yellow warning against heavy fog, which shrouded the city.

According to state-run media, the fog was so dense it caused visibility to drop to about 30 to 60 feet in some areas of the city. About 120 departing flights were cancelled over the weekend.

But the heavy fog that lingers since the weekend is actually smog. This is based on the air quality index readings from the US Embassy in China.

The smog from the pollution was so dense that residents could hardly see the top of buildings. Traffic was brought to a crawl in some parts of the city. Commuters were forced to wear masks.

According to The Wall Street Journal on Monday, Chinese authorities had to cancel more than 300 incoming flights. The thick grayish smog temporarily closed major expressways.

To the make situation worse, Beijing residents receive different air quality reports.


 


Figures from Chinese authorities show only 'slight pollution,' whereas the hourly air quality readings from the US Embassy indicate "very unhealthy" or "hazardous" pollution.

This inconsistency in the readings is due to Chinese authorities measuring bigger particles—between 2.5 to 10 microns.

But, the US Embassy's monitoring device includes measuring particles smaller than 2.5 microns, or PM2.5 air quality index. This is more accurate, as the finer particles are more dangerous to people's health.

The huge difference in the United States and Chinese air quality index triggered an outpouring from millions of Chinese netizens.

The Wall Street Journal cited one Sina Weibo blogger stating, "Beijing is dangerous."

Early last month, heavy smog covered Beijing—sending many residents with lung and breathing problems to the city hospitals' emergency rooms.