Thursday, January 22, 2015

APEC blue in China: air pollution data are censored after controversy on PM2.5 data released from US-Embassy in Beijing

The air pollution in Beijing and surrounding areas were supposed to be reduced by one third before the November 2014 APEC meeting, through a series of air pollution control measures.

"China will take action at the highest level to ensure air quality during the APEC meeting," said the vice president of the Chinese Academy of Environmental Sciences."It is expected that the discharge of pollutants in the Beijing-Tianjin-Hebei region will be reduced from 30 to 40 percent, and air quality will hopefully be further improved," he had said.

To prepare this APEC meeting scheduled from 8 to 10 Nov. 2014, Beijing had closed since June 2014  some of its plants, eliminated the old vehicles, used clean energy, and closed more than 300 polluting factories to reduce emissions.The use of car based on an even or odd number depending of the day was also planned to reduced by almost half the number of cars in the meeting.

Vice Premier Zhang Gaoli stated that the guarantee of the quality of the air for the APEC meeting was the "top priority".

Nevertheless the above picture is showing vehicles driving on Beijing's Fourth Ring Road amid heavy smog, on Oct 24, 2014 [Photo/Agencies]. 

The AQI issued on a daily basis by the various AQI data providers on the internet,  including MEP and US Embassy in the run up of APEC meeting were showing that the pollution was not controled and also extremely high. 

Government efforts to control smog ahead of the Nov. 5-11 Asia-Pacific Economic Cooperation events in Beijing had gained so much attention that the clearer skies programme got a nickname, “APEC blue”. 

China government after failing to clean the skies before APEC meeting tried to put the blame on the smog data providers and especially the US Embassy and decided to block all MEP AQI and Air pollution data publications. 

Why censoring the monthly publications of air quality and pollution data of the 190 major Chinese cities released from Jan. 2014?

As a consequence the monthly publications of air quality and pollution data of the 190 major Chinese cities (AQI derived from the concentration of the various pollutants: PM2.5, PM10 etc..) are censored by the China’s Ministry of Environment Pollution (MEP) since November 2014.

No air quality data was provided concerning the last two months of 2014, which will prohibit - if the MEP deadlock is maintained- to assess urban air quality for the 190 cities throughout 2014.

This interruption is very damaging to the complete information of the population on the quality of the air, in order to prevent the risks and prepare the provisions to be taken.

 What was really the situation of Beijing Air Pollution using the available data from MEP and US Embassy?

The air quality index (AQI) and associated pollutants concentration were obtained from the monthly average of the 190 main cities released progressively by MEP since 2013. No detailed data is provided concerning hourly and daily air pollutant apart from the number of days where AQI is above 100 or 50. As the PM2.5 is most of the time the main pollutant AQI is in clause relation with the PM2.5 level with AQI=135 when PM2.5=100 for instance (see my blog dated 11 Dec. 2013).

The air pollution data from US Embassy are obtained from the US Stateair feed 

They include the hourly PM2.5 only on 5 cities Beijing, Shanghai, Guangzhou, Chengdu and Shenyang.  These cities are among the biggest in PRC with Shanghai N°1 (22Mil), Beijing N°2 (19Mil), Guangzhou N°4 (11Mil), Chengdu N°8 (7Mil) and Shenyang N°14 (6Mil).  These cities are being reported by MEP since Nov. 2013 and we have a 12 months past information comparable to the US Embassy data.  

The following figure 1 is showing monthly PM2.5 concentration in Beijing as issued by MEP or US Embassy on the latest 12 months period available ( Nov. 2013 to Oct. 2014) plus an estimation of Nov. 2013 based on US Embassy.

The missing Nov 2014 PM2.5 of Beijing average is estimated from Nov. 2014 PM2.5 at US_Embassy by applying Nov 2013 correlation number (1.26) between both Nov 2013 concentrations.

Beijing monthly average increased by 19% compared to the value in November 2013. However, this situation is a major effort of the municipality to reduce pollution for the duration of the APEC meeting and this results necessarily more pollution than when the situation is normal!

Figure 1: Monthly PM2.5 concentration in Beijing as issued by MEP or US Embassy on Nov. 2013 to Oct. 2014 plus an estimation of Nov. 2013 based on US Embassy

Altogether, both data are extremely comparable because the US Embassy is a specific location in Beijing while the MEP monthly is averaged on the entire Beijing Municipality area which is around 17000km2 with a great variety of density between urban districts (30000 people/km2) - where is located the US Embassy- and suburbs  4000people/km2.

On the other hand the MEP does not provide information on hourly detailed pollution in specific sites where pollutants are measured. And the method used to determine the average value for the entire city is unknown: is-it an arithmetic mean or is it weighted by the density of the urban population?

What is the relationship between hourly, daily and monthly PM2.5 in Beijing?

The figure 2 below compares for PM2.5 concentration daily data issued by US Embassy with monthly MEP data. We see arge number of high daily values even for the month of November 2014 with 2 days with PM2.5 daily value >300µg/m3.

Figure 2:  Comparison of PM2.5 measurements daily  (US Embassy) or monthly values (MEP)

During the measuring period of 13 months or 395 days, there were all together 121 days or 31% of the total days where PM2.5 > 115µg/m3, which is about AQI> 150. We find comparable figures concerning MEP considering it is over a period of 12 months. However, we see that MEP needs  to specify the values of PM2.5 that are greater than 100, because there are lots of very high values

Tuesday, September 30, 2014

Most threatened coral reefs in the world are located in Southeast Asia

Thermal stress can cause coral reefs to bleach from losing their symbiotic algae giving them colour  (from imgarcade)

Coral reefs are not only a critical habitat for numerous species, they provide also essential ecosystem services such as:

  • For food and livelihood a healthy, well-managed reef can yield between 5 and 15 tons of fish and seafood per square kilometer each year;
  • Reefs are vital in many tropical countries for developing eco-tourism new revenues:  attracting divers, snorkelers, and recreational fishers, not to mention providing much of the white sand for beaches;
  • Many reef-dwelling species have developed complex chemical compounds- such as venoms and chemical defenses- aiding their survival in highly competitive habitats which might offer the basis of life-saving new pharmaceuticals including treatments for cancer, HIV, malaria, and other diseases;
  • Beyond their biological value, reefs dissipate wave energy, reducing erosion and lessening damage during storms with an estimated 150,000 km of reef bordered shoreline in more than 100 countries and territories; this function protects human settlements, infrastructure, and valuable coastal ecosystems such as sea grass meadows and mangrove forests.

Despite their importance, coral reefs face unprecedented threats throughout most of their range and many reefs are already degraded and unable to provide the vital services on which so many people depend.

Some threats are highly visible and occur directly on reefs. Levels of fishing are currently unsustainable on a large proportion of the world’s reefs, and have led to localized extinctions of certain fish species.

Many threats are also the result of human activities occuring far away from reefs, such as forest clearing, crop cultivation, intensive farming, polluted sewage runoff and poorly planned coastal development. Pollution and waste from ships and from oil and gas exploitation further exacerbate the situation.

Furthermore beyond these extensive and damaging local-scale impacts, reefs are increasingly at risk from the global threats associated with rising concentrations of greenhouse gases in the atmosphere.

Even in areas where local stress on reefs are relatively minimal, warming seas have caused mass coral bleaching occurring when corals become thermally stressed and are massively losing  the “zooxanthellae” symbiotic algae that live within their tissues and normally provide their specific colors.

It is rare for any reef to suffer only a single threat. More often the threats are compounded. For instance, overfishing eliminates a key herbivore such as “Parrot fish”, while runoff from agriculture supplies nutrients that cause a bloom in macro algae, impairing the growth of coral and ultimately reducing the competitive ability of coral communities.

Despite widespread recognition that reefs are severely threatened, information regarding threat assessment  to specific reefs are limited. Only a fraction of reefs have been studied or monitored consistently over time- such as Jamaica, Florida, and Australia’s Great Barrier- where changes in coral condition are well-documented. 

In most places, however, the availability of detailed information is limited, inhibiting effective management.

More than 15 years after the foundation of the World Reef Initiative (WRI), reef maps are showing clearly that the growth in threats has largely outpaced efforts to address those threats. 

In the mid-1990s, climate change was still perceived as a somewhat distant threat. However, in 1998, a powerful El Niño event further increased sea surface temperatures that were already rising due to climate change, triggering the most severe and expansive coral bleaching event on record.

As a result an update of the global coral reef threats analysis is clearly necessary in order to identify and understand the outcome  and implications of changes to the world’s reefs and to help guide targeted interventions aimed at mitigating existing threats .

Ranking of worldwide human threats to coral reefs

(see “WRI-Coral Reefs at risk revisited-2011”)

There is a difference between threats and damages. A threat analysis is an assessment of the likeliness (within 0-100%) of a specified type of damage.  A threat model measures threat rather than real conditions. 

Concerning coral reefs, harmful damage might result from the following threats:

  • Overfishing and destructive fishing : such as destruction of fish habitat and species;
  • Watershed land-based pollution : discharge of land base sediment or pollutant ;  
  • Coastal development : sewage and pollutions from ports, industry, resorts;  
  • Marine-based pollution and damage : discharge of marine waste and marine fuels;
  • Thermal stress : damage from sea surface temperature increase.

Figure 1 : Worldwide human local threats to coral reefs  (WRI 2011)

Overfishing and destructive fishing

Threats to coral reefs from overfishing were evaluated based on coastal population density and extent of fishing areas, with adjustments to account for the increased demand due to proximity to large populations and market centers.

Areas where destructive fishing occurs (with explosives or poisons such as cyanide) were also included, based on observations from monitoring and mapping expert analysis.

The threat estimate was reduced inside marine protected areas rated by experts as having “effective” or “partially effective” management (meaning that a level of management is present that helps to guard ecological integrity).


  • Accurate, spatially referenced global data on fishing methods, catches, and number of fishers were not available; therefore, population pressure is used as a proxy for overfishing.
  • The model fails to capture the targeting of very high value species, which affects most reefs globally, but has fewer ecosystem impacts than wider scale overfishing.
  • Management effectiveness scores were only available for about 83% of the reefs within marine protected areas.
Reef regions ranking for overfishing and destructive fishing (see Figure 2 below): most threatened are Southeast Asia (N°1) & Atlantic (N°2); less threatened are Pacific (N°5) and Australia (N°6).

Watershed land-based pollution

The threat from land-based pollutants was modeled over 300,000 watersheds (catchments area drained by a river and its tributaries) discharging to coastal waters. Relative erosion rates were estimated across the landscape based on slope, land cover type, precipitation, and soil type.

Sediment delivery at the river mouth was estimated based on total erosion in the watershed, adjusted for the sediment delivery ratio (based on watershed size) and sediment trapping by dams and mangroves.

Sediment plume dispersion was modeled using a linear decay rate and was calibrated against actual sediment plumes observed from satellite data. The model represents a proxy for sediment, nutrient, and pollutant delivery.

  • Nutrient deliveries to coastal waters were probably underestimated due to a lack of spatial data on crop cultivation and fertilizer application. However, agricultural land is treated as a separate category of land cover, weighted for a higher influence.
  • The model does not incorporate nutrient and pollutant inputs from industry, or from intensive livestock farming, which might be considerable.
Reef regions ranking for watershed land-based pollution (see Figure 2 below)most threatened are Southeast Asia (N°1) & India (N°2); less threatened are Middle East (N°5) and Australia (N°6)

Coastal development

The threat to coral reefs from coastal development was modeled based on size of cities, ports, and airports; size and density of hotels; and coastal population pressure (a combination of population density, growth, and tourism growth).

  • Indicators were likely to miss some new constructions works and tourism locations.
  • The model does not directly capture sewage discharge, but relies on population as a proxy for costal development threat.
Reef regions ranking for coastal development (see Figure 2 below)most threatened are Southeast Asia (N°1) & India (N°2); less threatened are Pacific (N°5) and Australia (N°6).

Figure 2 : Comparison of local and past thermal threats by region (WRI 2011

Marine-based pollution and damage

Threat from marine-based pollution and damage were based on the size and volume of commercial shipping ports, size and volume of cruise ship ports, intensity of shipping traffic, and the location of oil infrastructure.


  • Threat associated with shipping intensity might be underestimated because the data were based on voluntary ship tracking, and does not include fishing vessels.
  • The threat model does not account for marine waste (such as plastics), discarded fishing gear, recreational vessels or shipwrecks, due to a lack of global spatial data on these threats.
  • The four local threats described above were then  combined to provide an integrated local threat index. Past thermal stress as described below were treated as an additional threat.
Reef regions ranking for marine-based pollution and damage (see Figure 2 above)most threatened are Atlantic (N°1) & Middle East (N°2); less threatened are Indian (N°5) and Southeast Asia (N°6).

Thermal stress

Estimation of thermal stress over the past 10 years (1998 to 2007) combining the following two data layers:

Past intense heating events. These were areas known to have had high temperature anomalies (scores of degree heating weeks > 8), based on satellite sea surface temperature data provided by NOAA Coral Reef Watch; and

Observations of severe bleaching from Reef Base (see ReefBase) .  

How to assess the outcome of threats which are real damage and true habitat condition on reefs?
A unique and important feature of the Reefs at Risk approach is its global coverage—assessing threats to all reefs, even those far from human habitation and scientific outreach. It is, however, a model, and it measures as explained above threat rather than condition. 
The only way to accurately assess condition is through direct measurement of fish, benthic cover (live coral, dead coral, algae, etc.), or other characteristics. Some reefs, including the Great Barrier Reef, have detailed and regular surveys covering numerous areas, but worldwide such observation or monitoring are sparse and irregular. 
Some threatened reefs may still be healthy, but many others might have already suffered some level of degradation.

Where are located the most threatened coral regions?

The Figure 3 & 4 below are showing that Southeast Asia (N°1 ranking) and Atlantic Reefs (N°2) regions are relatively the most threatened reef regions in the world; then slightly better:  Indian Ocean (N°3) and Middle East (N°4); then Pacific (N°5) less than the averaged global risk; Australia's Great barrier reefs being much less threatened (N°6).

Globally, after factoring by the coral reef regions' area, more than 60% of worldwide coral reefs (about 150,000 km2) are threatened by human local activities (see Figue 3 below) and about 75% (about 185,000 km2) are threatened when past thermal stress is included. 

Figure 3 : Integrated local threats consist of the four local threats—overfishing and destructive fishing, marine pollution and damage, coastal development, and watershed-based pollution

Figure 4 : Amount of reef area (in sq km) in each region classified by integrated local threat categorized as low, medium, and high; the four local threats are integrated plus the thermal stress during the past ten years; this figure summarizes current threats: future warming and acidification are not included

On all counts of relatively (see Figure 3 above) or absolute (see Figure 4 ) threats Shouteast Asia is always the most threatened reef regions in the world and Australia is always the best ranking.

This means that the Southeast Asia is definitely the place where the long-term conservation of coral reefs in the world is at stake, including the survival of many biological species that live there.

Monday, September 29, 2014

The largest coral reefs in the world and the most valuable for their biodiversity are located in Southeast Asia

Most worldwide coral reefs are located in the Indian & Pacific and a small portion of Atlantic oceans 

Coral reefs and old growth forests are both nature richest realms. They are deriving their primary energy from plants thriving from solar radiation. As a result their location is within 30°S & 30°N latitudes where sun activity and temperature are at their maximum. Both are extremely complex systems consisting of numerous micro habitats and huge number of species.

Coral reefs today represent a development episode of only some thousand years ago when sea level remained relatively stable, because 15,000 years ago seas were as much as 150m below the present level. As explained by Charles Darwin’s theory for Coral Reefs development they are closely related to volcano island subsidence and sea level fluctuations.

Environmental conditions exert a great influence on determining how an individual coral polyp copes with its basic needs. Optimum coral reefs are strongly correlated with very clean and relatively shallow waters (<70m depth) to obtain maximum sunlight at a warm temperature (optimum 23°-24°C).

But during periods of million years, succeeding generations of coral species became gradually modified in a manner allowing them to utilize most efficiently their environment. The end result is communities of organism that are finely tuned to their environment.

 Why should we care about coral reefs in Asia Pacific?

Southeast Asia contains the largest area of coral reefs in the world known as the Coral Triangle shared between Indonesia, Malaysia, Philippines, Timor-Leste, Papua New Guinea and the Solomon Islands, .

The biodiversity of coral reefs in Southeast Asia is unparalleled in the world according to the Global Coral Reef Monitoring Network in their 2008 report on the status of coral reefs.

More than 138 million people in Southeast Asia live on the coast within 30 km of a coral reef, which is more than in all of the other coral reef regions combined. Fish, including reef fish, form a major part of the diet even in urban populations; across the region, fish and seafood provide an average of 36% of dietary animal protein.

Among the coral triangle countries, such as Malaysia and the Solomon Islands, tourism had enabled a rapid diversification of the economy and coral reefs had become one of the most attractive destination.

Contribution of observation satellites to coral reef mapping and monitoring

Since the late 1990s, the contribution of satellites for remote sensing of coral reefs has been fundamental to improving their mapping and monitoring. 

The observation satellites – such as Landsat (USA), Spot (EU) or IRS (India) - with optical sensor resolutions ranging from 10 to 50 m and capable of recording the radiation emitted in the visible and IR by the benthic environment, make it possible to obtain after treatment very accurate mapping of coral reefs, while monitoring their health and surveying the quality of their environment (bleaching thermal stress).

Specific treatments can eliminate noise as sun glint factors of the marine environment. The study of spectral signatures help to differentiate the various components of the benthic coral habitat: type of coral, living or dead, type of coral rubble, type of green algae or red by the absorption due to the presence of specific pigments, discrimination of coral sand or silt sediments by their reflectance, correction of the light signal attenuation in the water column by bathymetric treatment etc.

The University of South Florida (USF) had provided an exhaustive worldwide inventory of coral reefs using high-resolution satellite imagery. By using a consistent dataset of high-resolution multispectral Landsat 7 images acquired between 1999 and 2002, USF characterized, mapped and estimated the extent of shallow coral reef ecosystems in the main coral reef provinces (Caribbean-Atlantic, Pacific, Indo-Pacific, Red Sea).

Similar studies were conducted in Europe (IRD) , Australia and Indonesia from the data supplied by Landsat, SPOT, satellites or IRS.

Distribution of worldwide coral reefs habitat by region

Under the project called the Millennium Coral Reef Mapping a team of international researchers compiled an updated inventory of all "marine protected areas" containing coral reefs and compared it with the most detailed and comprehensive satellite inventory of coral reefs. 

The World Reef Initiative (WRI) was founded in 1994 by eight governments: Australia, France, Japan, Jamaica, the Philippines, Sweden, UK, and the USA. It was announced at the First Conference of the Parties of the Convention on Biological Diversity in December 1994, and at the high level segment of the Intersessional Meeting of the U.N. Commission on Sustainable Development in April 1995. 

The main result concerning the distribution of worldwide coral reefs by region is summarize in the following Figures 1 & 2 (see RWI 2011 Coral Reefs revisited ).

The world’s coral reefs are covering an area of approximately 250,000 sq km which the richest concentration being in Southeast Asia (30% of all coral reef areas in the planet), then Pacific (28%) and Australia (17%), followed by Indian Ocean (13%), Atlantic (10%) and the Middle East (6%) (see Figure 1 & 2).

Figure 1: Distribution of Coral Reefs by regions (From WRI 2011)

Figure 2 : Distribution of Coral Reefs and the associated population by regions (From WRI 2011)

Coral Reefs associated human population   

As reported in WRI “Reefs at risk revisited -2011” , the coral’s reefs associated worldwide population could be featured by two values:

-          Close population within 10 km of coast and 30 km from the reef            : 275 Mil

-          Larger area population within 100 km of the reef                                   : 850 Mil

Figure 3 : Population associated with coral reefs by regions

There is a great variation of the population close to the reefs: 

-          Highly populated reef areas are: Indian Ocean 2065.5 people /km2; Southeast Asia 1,983.9, Atlantic 1,645.8 and  Middle Eas 1,322.4

-          Low populated reef areas are: Pacific 113.5,  Australia 82.9

The ratio between larger and close area populations for reefs region is more or less stable between  2.5 (for low population countries) to 3.5 (highly populated).

Are coral reefs doomed to shrink progressively? 

We must never forget that when we are seeing the coral reefs distribution around the world such as the one presented here, it is a snapshot in a development episode of some 5000 years of coral reefs life. 

Coral have disappeared or have been  greatly reduced in every part of the world. 

Over the past 50 years for example, the Great Barrier Reef in Australia has decreased by 50% due to agricultural and industrial development of the western side of Australia!

Most of this coral reef reduction is due to the extraordinary development of people living on Earth which increased by a factor of 2.3 in average over the past 50 years, due to the correlative increase or human population direct or indirect pressure on coral reefs which are  particularly heavy in the Asian Pacific region.

So our ocean and coral reefs are changing a lot and what we see today- if we don’t take the greatest care - maybe is doomed to shrink progressively! There in the contemplation of the beauty of corals a fragile and transient aspect and perhaps we must keep the memory of what will perhaps one day disappear.

Such is the aim of the Catlin Seaview Survey study  which is a unique global study, working with some of the world's leading scientific institutions, dedicated to monitoring our oceans change and communicating on it to the world.

The aim of the survey is to document a baseline record by video and pictures of the world’s coral reefs seaview, in high-resolution panoramic vision.

Our oceans are changing and coral reefs are a clear visual indicator of this change – with a 40% loss of corals around the globe in the last 30 years alone. 

The painstaking work that scientists realize could well be a kind of archive that will be quickly out of date  due to ocean acidification, bleaching of the reefs, death of species and habitat.

In addition to their aesthetic appeal, coral reefs are also natural defenses against waves and coastal erosion. Their disappearance is a double punishment face of rising sea levels, expected over the next century.

Thursday, August 7, 2014

China's Provinces air pollution ranking from Jan to Jun 2014: Hebei, Hubei, Henan, Beijing, Shaanxi, Tianjin, Xinjiang & Shandong had more than 50-72% of exceedance days

Bubble pie map of provinces and municipalities over the first six months of 2014 

The 8 following regions and municipalities (see Figures 2 & 3) have had the highest population-weighted average urban air pollution (1st quintile): Hebei, Hubei, Henan, Beijing, Shaanxi, Tianjin, Xinjiang & Shandong. They concern a population of 139 Mil. 

These regions and municipalities have had 90-149 exceedance days (50-72% of total 181 days) above the threshold of 100 (AQI) and 75 µg/m3 (PM2.5).

The best regions and municipalities (5th quintile) were Hainan, Yunnan, Fujian, Tibet and Guangdong with only 4-18% exceedance days. 

Figure 1 :  Air pollution provinces & municipalities urban air pollution ranking over the first 6 months of 2014 (Jan. to Jun. 2014: 181 days)

The 8 most polluted regions or municipalities are: Hebei (13Mil pop); Hubei (12 mil); Henan (12 Mil), Beijing (19 Mil); Shaanxi (17 Mil); Tianjin (11 Mil); Xinjiang (4 Mil)  & Shandong (50 Mil). AQI is around 120-160 and there are more than 55% of days with AQI>100 (90 on 181  days).

As explained in my post dated 22 Sep 2013, AQI is a random variable with a log normal distribution and the repartition of daily AQI above 50 or 100 AQI is more or less correlated with the average AQI value. 

The correlation is good for days with daily AQI>100,  less good for days with AQI>50 and more loose for days with 50< daily AQI <100.

Figure 2 : Correlation between average AQI and daily AQI repartition

Air pollution in China from Jan to Jun 2014 far exceeds all limits put forward by UE or US standards : out of the 190 major cities, the highest 38 air pollution ranked cities have a population of 113 Mil with 125 exceedance days (70% of days), above 100 AQI or 75µg/m3 (PM2.5)

Bubble pie map of cumulated number of daily AQI repartition over the first six month of 2014 (Jan. to Jun. 181 days)

During Q2-2014, there had been only a slight improvement of urban air pollution over Q1, but we still have AQI>100 over 31% of days (29 days over 81 days) for the 190 monitored cities by China’s Ministry of Environmental Protection (see June 2014 MEP Chinese city air quality ranking).

After the first 6 months of 2014: the first 38 air pollution ranked cities out of 190 main Chinese cities (1st quintile) could be considered as the “core urban polluted area” comprising around forty cities - among them Jinan, Wuhan, Xi'an, Beijing, Chengdu. This core urban area population of 113 Mil, after 6 months, have had in average 125 cumulated exceedance days (70% of total 181 days), above 100 AQI or 75µg/m3 (PM2.5).

This is far exceeding the health exceedance limits put forward by EU and US air pollution standards where the maximum exceedance days permitted is around 35 days in one year!  

It means that the concerned population had been exposed to a harmful air pollution level 7 times more important than the level permitted by health regulations.   

Air pollution health standards 

Following our last post dated 21 July 2014, it is necessary to look more thoroughly at Chinese cities’ daily AQI inside the first six month period. This information– numbers of days with daily AQI>50 or AQI>100 - are provided each month by China’s Ministry of Environmental Protection (see June 2014 MEP Chinese city air quality ranking), along with the monthly average of the main pollutants and the resulting AQI

Concerning human health issues we know that what really counts is not the average AQI over defined monthly, quarterly or 6 months periods - qualified as moderately polluted (50<AQI<100) or unhealthy for sensitive groups  (100<AQI<150)- but the number of cumulated days where daily AQI has been above a defined dangerous limit. The longer the cumulated effect the more dangerous it is.

There is a cumulative effect especially for fine particulate matter: after some days of exposure above this limit a high number of tiny particulate are entering the lung’s cells. In the coal mining industry the dust contained in the inhaled breath is transforming progressively the lungs in stone after days and years of continuous silicate inhaling (silicosis).

Even if AQI level is classified as lightly polluted following China's standards (or “Unhealthy for sensitive group” as denominated by US standards): maintaining this risk level for a lengthly period could be extremely harmful to health. This is the notion of exceedance days permitted by the air pollution standards:

-     For EU (2008-2010) over a yearly period, there should be less than 36 exceedance days (10% of days) having air pollution above 50 µg/m3 (PM10) or 50 (AQI);
-     For USA (2012) over a period of 3 years, there should be less than 2% exceedance days above 35 µg/m3 (PM2.5) or again 50 (AQI).

As fine particulate matter in China’s city are almost always the main air pollutant as explained in our previous surveys, the number of exceedance days above 50 - 100 (AQI)or 35-75 µg/m3 (PM2.5) thresholds are two risk levels to consider with a target of a maximum exceedance days permitted each year .

In the following survey - due to the extremely air polluted China’s situation- we are considering mainly an interim target of 36 exceedance days in a  year (10%) above 100 (AQI) or 75 µg/m3 (PM2.5).

Situation in China of daily AQI  over Q1 & Q2-2014 or 6 first months of 2014

Over Q1 and Q2- 2014, daily AQI had been above 100 during 40% of days (73.6 days over 181 days).

During Q2 there had been only a slight improvement on Q1, but we still have AQI>100 over 32% of days (29 days over 81 days).

These values are population weighted average over the monthly values of the 190 monitored cities.

Figure 1: Average population-weighted evolution of urban daily AQI over first 6 months 2014

The geographic repartition of urban air pollution is described in zoomed in Figure 2 below: the most polluted urban area or “core polluted area”concerns a urban population of 113 Mil people (2010 census) where 75% of days have been AQI>100!

Figure 2: Bubble pie map of daily urban air pollution in Northern, Middle and Southern China’s regions showing the “core polluted area” (half circle in red) of the 38 worst air polluted cities (first air pollution quintile ranking).

The detail evolution over the 6 first months of 2014 of this “core polluted area” is described in the following Figure 3:

-    38 cities with an overall population of 113 Mil had in average 125 exceedance days (70% of total), above 100 AQI or 75µg/m3 (PM2.5);

-    5 cities in Q1 and 10 cities in Q2 are not in the concerned 6 first months core polluted area;
-    Concerning the biggest cities improving their air quality: Xi’an (Shaanxi) N°12 in Q1 , N°25 on 6 months; Weinan (Shaanxi) N°16 in Q1, N°27 on 6 months; and Chengdu (Sichuan) N°24 in Q1, N°36 on 6 months;
-    The biggest cities reducing their relative ranking air quality: Beijing N°42 in Q1, N°30 on six months; Tangshan (Hebei) N°15 on Q1, N°9 on 6 months; Jinan (Shandong); Wuhan (Hubei) etc…

Figure 3 : First quintile air pollution ranking cities and cumulated days where daily AQI is > 100

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