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High Levels of Particulate Pollution in Chinese Megacities

A team of researchers from China and Japan has concluded the first study comparing levels of organic aerosol particles in China’s newly developing midwestern cities with levels in older megacities such as Beijing, Hong Kong and Shanghai.

The research confirms that most of the 14 cities studied have much higher levels of air pollution than cities in developed countries.

The study, the most comprehensive yet of organic pollutants in Chinese urban air, was posted to Environmental Science & Technology’s Research ASAP website today.

Particulate matter (PM) made up of microscopic airborne particles less than 10 micrometers (µm) in diameter (PM10) is recognized worldwide as a potential cause of respiratory and cardiovascular health problems.

PM10 aerosol particles can include a complex mix of inorganic and organic compounds, dust, and soil, and they are a major cause of reduced visibility in urban areas. Fine particles less than 2.5 µm in diameter (PM2.5) pose an even greater threat to human health because they can penetrate deeply into lung tissue.

The World Health Organization (WHO) estimates that outdoor particulate pollution accounts for 800,000 premature deaths in the world annually, including 500,000 in Asia alone.

The researchers designed the study to sample PM2.5 aerosols in 14 cities across China during 2 summer days and 2 winter days in 2003. The sampling conducted during the winter was done simultaneously in all 14 cities. The data collected over four days was consistent with earlier reports from individual cities, suggesting that the results are representative.

The levels of most of the 114 organic compounds identified in the new study were higher during the winter. The study’s authors attribute this mainly to the burning of coal for domestic heating. By comparing chemical fingerprints, the researchers could determine whether the pollutants originate from anthropogenic sources, such as coal or vehicular exhaust, or natural sources, such as plants or microbes.

According to China’s State Environmental Protection Administration (SEPA), China burned 2.14 billion tons of coal in 2005, accounting for nearly 70% of the energy the country consumed that year. Coal burning may explain why the predominant PAH detected was benzo[b]fluoranthene, according to the study’s authors.

This is totally different from cases in other countries, especially in developed regions, where PAHs [Polycyclic Aromatic Hydrocarbons] are mainly derived from petroleum combustion (e.g., vehicular exhausts) and benzo[ghi]perylene is the most abundant PAH in the air.

—Gehui Wang

Kimitaka Kawamura of Hokkaido University (Japan), the study’s corresponding author, notes that “This may be changed soon because the numbers of motor vehicles are increasing quickly.” In 2005, the number of registered motor vehicles in China jumped to more than 31 million, an increase of 30% from 2004.

SEPA regularly monitors urban air quality in the country’s major cities. Among the measured compounds, SO2 and PM10 are the most prominent pollutants. In 2005, SEPA reported that of 522 cities, 4.2% reached grade I (which equates to the lowest levels of pollution) of SEPA’s National Ambient Air Quality Standards (NAAQS), and 56.1% reached grade II. The remaining 39.7% had grade III (inferior) air.



Rafael Seidl

Chinese officials would be wise to remember that environmental pollution was a major contributing factor in the collapse of the Soviet Union. Using unprocessed coal for home heating in densely populated cities is a recipe for a chronic public health crisis (cp. the infamous smog in Victorian London).

In areas already built up, it may make sense to at least switch to small pellets pressed from pulverized low-sulphur coal grades. Longer-term, coal should be replaced with heating oil or bottled propane gas in all stand-alone residential heating applications.

China has very little natural gas at its disposal. Therefore, new residential, commercial and industrial developments should be set up for district heating from a local power plant. In summer, the exhaust heat can be used to drive an absorption chiller for air conditioning. If such a plant must be operated on coal, it should feature fluidized bed combustion or gasification, sulphur and chlorine neutralization, particulate filtration and NOx scrubbing via SCR. If not all of these components can be in place from the outset, the layout of the plant should permit their addition in future upgrades.

Out in the countryside, pelletized dry biomass would be preferable to coal, if only to avoid high SOx levels that are as harmful to crops and livestock as they are to humans. Besides, biomass is a locall produced renewable fuel with zero net CO2 footprint.

allen zheng

The cost of not putting in environmental controls have come home to roost. Bigger profits (or being in the black instead of in the red) few years ago for some, now mean death (or premature death). Ironically, it may reduce the trade deficit; high tech (and expensive) pollution controls may be exported from the West/US... but then again, they will demand we hand over trade/tech secrets on the equiptment for access to Chinese markets, just like before.
____Due to pollution (and due to growing shortage of child bearing females), birth defects are up as well as an unhealthy population. This will raise health costs, and reduce productivity (growth).
____If the PRC leadership does not wake up and smell the toxic air/water/soil, it will ensure their downfall, one way or another. The only difference in those scenarios is if other countries suffer (and how much) the consequences (indirect/direct/domino consequental, etc.).


Of course Third World Countries are going to be behind the standards of 1st and 2nd World.

But its also up to us to share technologies to bring them up to code.

Was Japan like this in the 60s???

But still on the global playing field . . .

We has a fragile world and we all has to play nice.

shaun mann

I like their grading system for air. This seem to be a trend in pollution reporting, hiding the facts behind meaningless descriptions. In countries that care, they report ppm of major pollutants.

My guesses as to what their grades mean:

grade 1 - you can see your own hands if you squint just right

grade 2 - you can walk up to 50 meters before coughing up a ball of tar

grade 3 - the testing officials did not return

grade 4 - site of the Olympics. so we've changed our grading system and now grade 4 is the best and represents the best air anywhere in the world.


China produces extremely cheap and effective solar water heaters that have become very popular throughout the country. Let's hope they expand this effort.

They should expand solar heating to space heating to supplement radiant floor heating. This would make sense considering that they have apparently perfect very low cost solar collectors.

As far as particulates goes, we have a double edged sword. Apparently, these particulates (so2) are contributing to global dimming which is reducing the effect of greenhouses gases. If they clean up their coal plants but keep turning out one plantper week, we will have a positive feedback effect which will make us doubly screwed as far as warming is concerned.

The U.S., of course, is not in a position to influence or pressure the Chinese since we are doing nothing and refuse to set any limits on our emission of greenhouses gases.

Rafael Seidl

t -

PM from domestic coal heaters is mostly unburnt carbon. SOx represents only a small portion of the mass but is dangerous because it forms H2SO4 on the surface of those particles.

I'm not sure how strong the global dimming due to PM supposedly is, but in any case diesel and coal exhaust fumes only account for a fraction of it. Much of it is extremely fine natural dust and pollen that gets transported into the upper troposphere. It's certainly not a cogent argument to keep pumping out anthropogenic PM.

Btw, the central government in China appears to be aware of the political risk associated with excessive pollution. It has ordered lower levels of government to restore the bicycle lanes that had previously been surrendered to cars. It is unclear if this directive will be heeded, many appear to be simply ignored these days, especially where environmental protection is concerned.

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