The PM_(10) daily value is set at 50|jg/m~3 24-hour mean with a maximum of 35 days a year. In Berlin the exceedances decreased by 45 per cent between 2005 and 2009. Zurich has also decreased the number of days. Some cities show decreasing numbers but have been given lower marks since figures appear to be inconsistent or there has been manipulation of the data. In Madrid for instance stations have been moved to less polluting areas.
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