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November 16, 2012

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City residents get better gauge of air pollution with stricter criterion

LOCAL residents are getting a more accurate and timely indicator of air pollution after a stricter air quality criterion was put into use today in Shanghai and in the neighboring provinces of Jiangsu and Zhejiang.

As of 12am, websites of local environment authorities started releasing the daily and hourly air quality index or AQI, while media are issuing AQI every day to inform the public of air quality. A smartphone application will be issued on December 1.

The new index is based on six indicators: PM10, sulfur dioxide, carbon dioxide, PM2.5, ozone and carbon monoxide levels. The previous air pollution index or API used three: PM10, sulfur dioxide and carbon dioxide. PM2.5 is a measure of airborne pollutants smaller than 2.5 microns in diameter, which are the main cause of urban smog.

Real-time air quality information is available online at, including daily and hourly readings and a chart of the six indicators. The English version will be available in three months.

AQI and each indicator are indicated by six levels, with each level given a different color. They range from green, which is excellent, to maroon, which is severely polluted.

A cartoon girl has hair the same color as the level each day and different facial expressions depending on air quality. It is used to convey the information at a glance, officials said.

The Shanghai Environmental Monitoring Center is holding an online vote for the most popular name for the girl among three: Lingling (smart), Duoduo (flower) or Xiaoqingxin (fresh). Netizens also can customize the site by having a name they pick appear.

In the new system, the daily index of air quality under AQI is evaluated for 24 hours from the previous midnight, while API is from the previous noon.

The monitoring center has stopped issuing air quality forecasts but instead is issuing alerts about pollution and adopting measures such as ordering heavy industry to use better quality coal, or delaying or stopping waste discharges during days of heavy pollution from local sources.

"Similar measures were used in the 2010 World Expo to reduce pollution," said Fu Qingyan, chief engineer of the center. "Restrictions on highly polluting vehicles will be tightened to encourage their elimination."

"Since the daily AQI readings and PM2.5 are evaluated on the basis of the past 24 hours, we suggest local residents check both AQI and hourly PM2.5 readings," said the center's Luo Hailing. "If the PM2.5 density remains above 150 micrograms per cubic meter for several hours, people should take precautions."

The nation's average daily limit of PM2.5 is 75 micrograms per cubic meter. The bureau and education officials will require schools to reschedule outdoor activities for severe pollution.

"In Shanghai, PM2.5 is serious in autumn and winter, while ozone is the top pollutant in summer," Luo said. Ozone is mainly from vehicle exhaust and industrial discharge reacting with sunlight.


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