May 6^th: The Air Quality data information for Japan is progressively going back to normal. If you notice any issue, please contact us.
March 22^nd: On Saturday March 23rd, from 20:30 to 21:30, the aqicn.info team will join the the Global Earth Hour.During this time, the website will be inaccessible
March 15^th: The Beijing AmCham is organizing a session on 'Air Pollution and Health: What You Can Do to Minimize Risk?' on Thursday March 21st 2013. More information available here.
March 11^th: We apologize for the service break which happened from Sunday 23PM until today, Monday, 9PM. This break was due to our web hosting provider.
February 21^st: Our new back-end server roll-out is started - with the objective to improve the incoming traffic bandwidth. If you notice any strange issue, please contact us.
February 7^th: The Air Quality Designation is now updated to follow the EPA standard. Check the FAQ for more information...
February 3^rd: 2 new entries posted in the faq section about Why is PM_2.5 often higher than PM₁₀ and Can masks really filter PM_2.5 particles?.
A problem has also been fixed in the server which prevented some of the android widgets from beeing updated. If you still see some problems with the Android widgets, please contact us.
January 19^th: Shanghai main AQI data is now based on the maximum of the PM2.5 AQI readings for the 3 stations Shanghai US Consulate (上海美国总领事馆),
Jingan (静安监测站) and Shanghai Normal College Primary Division (上海师范专科学校附属小学) (Same as for Beijing, Guangzhou and Chengdu; done to minimize maintenance downtime)
If you want to compare the relative AQI readings for those 3 stations, consult the FAQ section
January 12^th: PM2.5 data is available for 11 new cities (Taiyuan, Huhehaote, Shenyang, Hefei, Fuzhou, Zhengzhou, Changsha, Nanning, Haikou, Lhasa, Wulumuqi)
January 11^th: Chengdu main AQI data is now based on the maximum of the PM2.5 AQI readings for the 2 stations Chengdu US Consulate (成都美国总领事馆)
and Caotang Temple, Chengdu (成都草堂寺) (Same as for Beijing and Guangzhou; done to prevent from the 'no reading downtime')
January 8^th: PM2.5 data is available for 12 new cities (Chongqing, Tianjin, Xian, Dalian, Xiamen, Haerbin, Nanchang, Changchun, Kunming, Xining, Lanzhou, Yinchuan)
December 30^th: Guangzhou main AQI data is now based on the maximum of the PM2.5 AQI readings for the 2 stations
US consulate, Guangzhou (GuangzhouUS consulate) and lìwān xī cūn, Guangzhou (广州荔湾西村) (Same as for Beijing; done to prevent from the 'no reading downtime')
December 29^th: PM2.5 real time data hourly is now avaialble Shandong province and Zhenjiang province
December 28^th: Since the Beijing US embassy PM2.5 is having 'no-reading' issues, the Beijing AQI data is now based on the maximum of the PM2.5 AQI readings for the 3 stations
Beijing US Embassy (北京美国大使馆), Dongcheng Dongsi (东城东四) and Chaoyang Agricultural Exhibition Hall (朝阳农展馆).
If you only want to view the PM2.5 US embassy data, then use this link. If you want to compare the relative AQI readings for those 3 stations, consult the FAQ section
December 8^th: We are looking for help to improve the translations for Chinese, Cantonese, Korean, Russian and Japanese, as well as create tranlations for new languages.
If you can help for those translations, please contact us at this link.
December 6^th: PM2.5 real time data hourly is now avaialble Hebei province (38 places), Guangdong province (63 places), Jiangsu province (17 places),
November 18^th: PM2.5 real time data hourly is now avaialble for Wuhan, Ningbo and Shanghai
October 7^th: The MEP PM₁₀, NO₂ and SO₂ convertion formula from µg/m³ to AQI level has been updated to follow EPA standards.
September 18^th: PM2.5 real time data hourly is now avaialble for Beijing, Hong Kong and Shenzhen
Beijing, Shanghai, Guangzhou, Chengdu Air Pollution Indexes are now based the US Embassy real time twitter feeds.

About the Air Quality and Pollution Measurement:

The pollution indices and color codes available on this web site follow the EPA graduation, as defined by AirNow and explained in wikipedia.

AQI	Air Pollution Level	Health Implications
0 - 50	Good	Air quality is considered satisfactory, and air pollution poses little or no risk
51 -100	Moderate	Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
101-150	Unhealthy for Sensitive Groups	Members of sensitive groups may experience health effects. The general public is not likely to be affected.
151-200	Unhealthy	Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects
201-300	Very Unhealthy	Health warnings of emergency conditions. The entire population is more likely to be affected.
300+	Hazardous	Health alert: everyone may experience more serious health effects

To know more about Air Quality and Pollution, check the wikipedia Air Quality topic or the airnow guide to Air Quality and Your Health.

For very useful health advices of Beijing Doctor Richard Saint Cyr MD, check www.myhealthbeijing.com blog.