Based on the 24 hour average API data published by Beijing EPB (http://www.bjepb.gov.cn/air2008/olympic.aspx), we can see that the dominant pollutant for the past weeks has been PM10. The PM10 levels in Beijing vary on a daily basis, but remain within the AQ Level II standard in China (below 150 micrograms/cubic meter).
To comply with national ambient air quality guidelines and to achieve targets for the Olympics, Beijing has been implementing measures to improve its air quality. To know more of these measures, click here.
To assess the improvements in air quality in Beijing over the past few years, one can look into trends in AQ concentrations or API trends.
Beijing AQ concentration
While annual average NO2 and SO2 levels in this city comply with national standards (Class II), PM10 levels continue to exceed the national limits.
Caption: Annual PM10 levels in Beijing since 2003 exceed both PRC Class II standards and annual WHO guidelines (20µg/m3).
Caption: Annual SO2 levels in Beijing have shown positive improvements since 1992. Since 2004, Beijing SO2 is now Class II-compliant but still is much higher than WHO SO2 guidelines.
Caption: Annual NO2 levels in Beijing have shown positive improvements since 1992. Since 2004, Beijing SO2 is now Class II-compliant but still is much higher than WHO NO2 guidelines (40µg/m3).
Beijing API Trend
In addition to observing annual AQ concentration trends, daily air pollution indices gives a better perspective on the short-term (daily) levels of air pollution in a city.
While Beijing has made improvements in achieving more combined Class I and Class II days since 2001 (to 2007) the percentage of days in a year are still below short of 70%. From a percentage of around 50% in 2001, there were only 67% of API-compliant days in 2007. This means that at least 30% of days in a year, the air in Beijing is not good according to PRC standards.
Since 2000, the average API for the month of August in Beijing is within Class II standards. Beijing has also managed to increase the number of days in August that API is 100 or below. From 12 days of non-compliance with Class II in August 2002, Beijing only had 3 days of non-compliance with Class II in August 2007.
|above class 2
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