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The maximum daily eight hour mean concentration of carbon monoxide must be selected by examining eight hour running averages, calculated from hourly data and updated each hour. Each eight hour average so calculated will be assigned to the day on which it ends, i.e. the first calculation period for any one day will be the period from 1700 hours on the previous day to 0100 hours on that day, the last calculation period for any one day will be the period from 1600 hours to 2400 hours on that day.
Lead
| Averaging period | Limit value | ||
|---|---|---|---|
| Calendar year | 0.5 µg/m3 |
PM10
| Averaging period | Limit value | ||
|---|---|---|---|
| One day | 50 µg/m3, not to be exceeded more than 35 times a calendar year | ||
| Calendar year | 40 µg/m3 |
PM2.5
| Averaging period | Limit value | Margin of tolerance | Date by which limit value is to be met |
|---|---|---|---|
| Calendar year | 25 µg/m3 | 20% on 11th June 2008, decreasing on the next 1st January and every 12 months thereafter by equal annual percentages to reach 0% by 1st January 2015 | 1st January 2015 |