![](http://www.telegraph.co.uk/telegraph/multimedia/archive/00778/beijing-smog-404_778961c.jpg)
Beijing Skyline, 18 July, 2008
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A study published in China alleges that air quality near the main Olympic venues fails the government's own "safe" target for dust particles on most days. The authorities say that air quality now nearly always meets overall pollution targets. Days that do are called "blue sky days".
In a last ditch effort to ensure unbroken "blue sky days" for next month's Games, the authorities yesterday implemented a final shutdown of heavily polluting industries across the city and neighbouring provinces. They also banned cars from the streets on alternate days, depending on whether their licence plates are odd or even. They cite the success of a similar driving ban implemented as a test during August last year.
But the authors of the study, from the Chinese Research Academy of Environmental Sciences, took independent readings following the earlier driving ban. Concentrations of three pollutants - sulphur dioxide, carbon monoxide and nitrogen dioxide - were low or acceptable, they found. But those of two of the most important as far as runners are concerned, ozone and "particulates" such as fine dust, were "much higher than the values of the standard".
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These readings often surprise visitors to Beijing, who are shocked by the smog visible even on a "good day". That is partly explained by the standard, which is more lax than that set by the World Health Organisation. For the key PM10 (particulates of 10 micrometers or less), Beijing defines its level two standard as 100 microgrammes per cubic metre, compared with 50 for the WHO. The new study, published in the journal Air Quality, Atmosphere and Health, collected PM10 measurements daily from Aug 17 to Sept 30 last year. The daily average was 190 microgrammes, nearly double Beijing's safe limit, which was breached on 34 out of 45 days. Ozone was measured from Aug 7 to Sept 30, and "good" limits were breached on 30 days out of 55.
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http://www.telegraph.co.uk/news/worldnews/asia/china/2437833/Olympics-Beijings-clean-air-claim-challenged-by-scientists.html