Thick smog grounds flights and fouls air

More than 100 flights in Beijing were grounded because of smog at dawn on Tuesday, according to Capital International Airport.

Visibility was reduced to less than 200 meters during rush hours, said the city's meteorological bureau.

Air quality worsened with the smog, with the US embassy's air pollution index reading 500 at 7 am on Tuesday and its PM2.5 measurement (particulate matter smaller than 2.5 micrometers) reading 513 micrograms a cubic meter.

The embassy issued a health warning of emergency conditions in the morning, saying "all people are more likely to be affected".

According to the Beijing municipal environmental monitoring center, the capital witnessed a rapid increase of inhalable particle density since dawn because of the fog, especially in southeastern and southwestern parts of the city.

The data showed the average Air Pollution Index, based on PM10 data collection, around the US embassy was 212 micrograms a cubic meter, with sulfur dioxide readings reaching 70 and nitrogen dioxide reaching 102. The smog began to disperse as the wind picked up at midday, allowing planes to take off and land, with visibility improving to 2,000 meters around 1 pm, according to airport.

The city's monitoring station started releasing the pollutant density data collected at the 27 stations around the city, including the sulfur dioxide, nitrogen dioxide and PM10 levels.

Since Monday, the station has provided detailed data by area instead of a general figure for the whole city.

In addition, hourly readings of pollutants will soon be issued instead of the daily figure, and data on PM2.5 will be announced before the start of Spring Festival, which falls on Jan 23, the bureau said.

The bureau has also promised to take measures to reduce air pollutants.

"Although the foggy weather keeps the pollutants from dispersing, the PM2.5 readings wouldn't be this high if the city's air were clean enough, however heavy the fog is," said Wang Qiuxia, a researcher at Green Beagle, an environmental protection non-governmental organization based in Beijing.

"The fog is not an excuse."