Beijing pollution: Facts and figures

In pictures: BBC pollution-watch

One of the biggest challenges facing Beijing in the final run-up to the Olympic Games is how to deal with the city's pollution problem.

The World Health Organization says air pollution figures for Beijing are still far higher than its recommended target level.

The Beijing authorities say pollution levels are coming down and they have introduced a series of measures, such as reducing traffic driving in to the city and stopping work at building sites, to bring down levels even further.

IOC President Jacques Rogge has warned that some endurance events might have to be postponed to a different time of day if pollution levels are very high.

But he has also cautioned that the "fog" that can be seen hanging over Beijing can be caused by humidity, and may not be a direct indicator of pollution.

THE PROBLEM

Air pollution in Beijing is a problem. Figures for particulate matter (PM10) - tiny airborne particles caused by the burning of fossil fuels like petrol in motor vehicles - are regularly several times higher than the WHO air quality guideline level of 50 micrograms/cubic metre.

In fact the WHO's usual target level - without allowing for daily and seasonal variations - is even lower, at 20 micrograms/cubic metre.

Beijing's figures even exceed the WHO's interim target for developing countries of 150 micrograms/cubic metre. The interim or "easy" target is intended to encourage developing countries to begin gradually cutting down emissions.

In Europe, rapid economic growth was followed only later by pollution control and China is following a similar trend James Reynolds blog: Pollution Your pictures: Beijing's skies

The Beijing authorities admit they are still having trouble bringing down PM10 levels, one of the main pollutants in the city.

The BBC is using a hand-held detector to monitor PM10 levels outside the BBC office in Beijing in early afternoon.

The Beijing Municipal Environmental Protection Bureau also publishes a daily reading based on an average figure for a 24-hour period taken from a variety of locations around the city.

For example, on Monday 28 July, the BMEPB reading was 98 - compared to the BBC's figure of 134.

There may be several explanations for the discrepancy: PM10 levels can vary widely during the day and the BBC's measurement is only a snapshot figure; different measuring tools can give different readings; and local factors such as a big fire, or a particularly busy rush hour, can also cause a sudden spike in PM10 levels.

According to the Beijing authorities, the number of "blue sky" days in the city, or days measuring less than 100 PM10/microgram per cubic metre, has increased from 100 in 1998 to 246 in 2007.

It is aiming for 256 days blue sky days in 2008.

BEIJING AND OTHER OLYMPIC VENUES

Beijing was ranked as the 13th most polluted city in the world in 2004. The World Bank list included many cities in China and India, where rapidly expanding industrial sectors were contributing to the build-up of air pollution.

In Europe, rapid economic growth was followed only later by pollution control and China is following a similar trend.

However, problems in Beijing have been exacerbated more recently by the large amount of building work in the city, some of it generated by the games themselves, which in turn is causing a lot of dust and contributing to PM10 levels.

Frequent dust and sand storms, a feature of the weather in Beijing, also contribute to the high levels of PM10. According to a report by the United Nations Environment Programme, Beijing suffered 18 sandstorms in the spring of 2006.

WORLD'S MOST POLLUTED CITIES

City	Country	PM10
Cairo	Egypt	169
Delhi	India	150
Kolkata	India	128
Tianjin	China	125
Chongqing	China	123
Kampur	India	109
Lucknow	India	109
Jakarta	Indonesia	104
Shenyang	China	101
Zhengzhou	China	97
Jinan	China	94
Lanzhou	China	91
Beijing	China	89
Taiyuan	China	88
Other Olympic cities
London	United Kingdom	21
Athens	Greece	43
Sydney	Australia	20
Seoul	Korea	41
Source: World Bank 2004

Concern has been raised about pollution levels at different Olympic venues in the past.

In Seoul, South Korea, host of the Games in 1988, traffic was banned because of fears about air pollution but the predicted problems did not materialise.

Similar fears were raised about the games in Athens in 2004, and Los Angeles in 1984.

London, which hosts the next Olympic games in 2012, already achieves daily PM10 levels below the WHO target.

In 2007, at a measuring station in Tower Hamlets, East London, close to the Olympic site, only 12 days measured above the WHO air quality target.

THE IMPLICATIONS

Endurance athletes are thought most likely to suffer the effects of pollution

The IOC is insisting there is no health risk to athletes taking part in the games. But it has said some events, like the marathon, triathlon and open water swimming may have to be postponed, or scheduled for a different time of day when pollution levels are lower.

In normal conditions, oxygen makes up about 21% of the air. High levels of PM10 means less oxygen passing through the lungs into the blood and to the muscles which, in turn, could affect athletes' performance times.

Athletes can take in up to 20 times more air than sedentary people and thus 20 times as much pollution. Once in the lungs PM10 particles can cause irritation and inflammation and exacerbate existing conditions such as asthma.

The athletes most likely to be affected are those taking part in endurance and longer events, who are most exposed to the pollution.

John Brewer of the Sports Science Academy in Slough, the UK, says no comparative studies have been made measuring the impact of air pollution on an athlete's performance in clean and polluted air.

But, he said, if air pollution levels in Beijing remained high, performance would be affected.

High levels of air pollutants are known to cause respiratory diseases. A WHO report in 2006 said 32.8 million people in China had COPD, chronic obstructive pulmonary disease, an umbrella term used to describe lung diseases such as bronchitis. Out of a total population of 1.3 billion, 39 million also had asthma.

WHO figures for 2004 show 110 people out of every 100,000 die from chronic respiratory diseases in China, compared to a level of 72 per 100,000 in the UK.

SOLUTIONS

The Beijing authorities have announced a series of measures to bring down air pollution levels. They include:

• Tough EU-standard emissions levels introduced for cars in March
• Since 20 July, traffic into Beijing has been restricted
• Factories and other industrial plants are being ordered to stop work or stagger opening times
• Coal-burning boilers are being replaced

The Beijing Olympic Committee insists it is on target for a pollution-free games.

Air pollution figures during the Chinese summer tend to be lower than the rest of the year. In fact, figures for July and August 2006 were both well under the WHO interim target.