Monday, July 21, 2014

Around two thirds of Chinese urban population during the first six months of 2014 have had 40% of days with an unhealthy daily Air Quality Index (AQI> 100)

Q2-2014 bubble map of China’s Air Pollution is showing a concentration of Air Pollution in 8 Northern and middle provinces or municipalities: Hebei, Beijing, Tianjin, Shandong, Jiangsu, Anhui, Henan & Hubei

The China’s urban Air Quality ranking is issued monthly by the Ministry of Environmental Protection (MEP), with Air Quality Index (AQI) and main pollutants concentration of the 190 biggest cities. The last updated data for June 2014 (MEP link ) was released this month.

AQI population weighted average over the 190 monitored cities decreased to AQI= 89 in the second quarter (Q2-2014) after AQI= 119 in Q1-2014.

The urban population concerned is around 435 Mil based mostly on the last 2010 census totaling around 66% of Chinese urban population.

Average days number with their daily AQI>100 decreased to 29.1 days (on 91 calendar days) during Q2 after 44.6 days (on 90) during Q1.

Daily AQI>50 decreased to 79.3 days during Q2 after 82.2 days during Q1.

Altogether on the first 6 months with an urban population of around 435 Mil we had AQI= 104 and on average 41% of the days with AQI>100 (73.7 days on 181) and around 90% of the days with AQI>50 (161.5 days on 181 or 89%).

This is far away from the limit for daily AQI specified by UE and USA:

UE air quality standards for 24-hour exceedance limit applies to the 90.4th percentile (cf. EU-PM10 limit), which means that AQI may be greater than 50 but less than 35 exceedance days (9.6% of calendar days) over a year, not to mention US exceedance limit (cf. US-PM2.5 limit) which applies to the 98th percentile over 3 years (see my blog dated 22 Sep 2014).

Here we can see on the first six month of 2014 that we have only 10th percentile of days under the AQI=50 limit!

Q2-2014 Air Pollution Ranking

The most polluted cities over Q2-2014 are the first quintile of the Air pollution Ranking (see Figure 1 below). They were mostly Northern with few Middle or Western cities :

Korla N°1 (Xinjiang), Xingtai N°2, Shijiasuhuang N°3, Baoding N°9 (Hebei), Jinan N°7 (Shandong), Zaoguang N°8 (Shandong), Tangshan N°10 (Hebei), Linyi N°14 (Shandong), Zibo N°15 (Shandong), Nanjing N°17 (Jiangsu), Beijing N°21 were the most polluted cities with monthly AQI average > 120, almost no day with AQI<50 and about 70 days on 90 calendar days (80%) with AQI>100.

Figure 1 : The first quintile of the Air pollution Ranking of 190 main cities

 Q2-2014 most important pollutants

As during Q1-2014 the leading pollutants for the AQI determination were mostly PM2.5 or sometime PM10.

The O3 pollution had shown an increase of more than 60% in Q2 over Q1: with O3 being the leading pollutant in some cities such as Rongshen, Wendeng & Weihai (Shandong), Lhasa (Tibet), Zhangjiakou (Hunan), Zhoushan (Zeijiang) or Shanwei (Guangdong).

The test made on the various pollutants’ sub indexes is showing some weird discrepancies such as Korla in April 2014 where AQI=245.93 with PM10 leading pollutant concentration value being 621μg/m3 (see MEP updatedin 1 May 2014) or even in May 2014 where AQI=234.06 with PM10 leading pollutant being  386μg/m3 (see MEP updated 1 June 2014 ).

Figure 2 : Pollutants’s population weighted averaged value in Q1 and Q2 – evolution in %

Most polluted urban areas

During Q2-2014  the core area of urban air pollution as compared to Q1-2014 (see my blog dated 26 May 2014) is less extended and more North- Southwest oriented with strong pollution in the following 8 Provinces or Municipalities:

Hebei, Beijing, Tianjin, Shandong, Jiangsu, Anhui, Henan & Hubei.

Figure 3 : Zooming of Q2-2014 bubble map of China’s Air Pollution showing the core area of urban air pollution

Overall situation during the first 6 months of 2014

The Provinces Air Pollution ranking over the combined first 6 months of 2014 is presented in Figure 4 hereafter.

The most remarkable aspect is the steady weight of Hebei, Hubei, Beijing and Tianjin in the Air Pollution ranking of provinces and municipalities throughout  Q1 and Q2.

Shaanxi (strong in Q1), Henan (Q1), Sichuan (Q1), Xinjiang (Q2) and Ganzu (Q2) provinces contributions are more fluctuating over the quarterly periods.  

Figure 4 : Provinces Air Pollution ranking  during 6 first months of 2014