A. Definitions
AOT40 (expressed in (μg/m3) ∙ hours) means the sum of the difference between hourly concentrations greater than 80 μg/m3 (= 40 parts per billion) and 80 μg/m3 over a given period using only the one-hour values measured between 8.00 and 20.00 Central European Time (CET) each day.
B. Target values
| Objective | Averaging period | Target value | Date by which targetvalue should be met (1) |
| Protection of human health | Maximum dailyeight-hour mean (2) | 120 μg/m3 not to be exceeded on more than25 days per calendar year averaged over three years (3) | 1.1.2010 |
| Protection ofvegetation | May to July | AOT40 (calculated from 1 h values)18 000 μg/m3 ∙ h averaged over five years (3) | 1.1.2010 |
(1) Compliance with target values will be assessed as of this date. That is, 2010 will be the first year the data for which is used in calculating compliance over the following three or five years, as appropriate.
(2) The maximum daily eight-hour mean concentration shall be selected by examining eight-hour running averages, calculated from hourly data and updated each hour. Each eight -hour average so calculated shall be assigned to the day on which it ends. i.e. the first calculation period for any one day will be the period from 17:00 on the previous day to 01:00 on that day; the last calculation period for any one day will be the period from 16:00 to 24:00 on the day.
(3) If the three or five year averages cannot be determined on the basis of a full and consecutive set of annual data, the minimum annual data required for checking compliance with the target values will be as follows:
— for the target value for the protection of human health: valid data for one year,
— for the target value for the protection of vegetation: valid data for three years.
C. Long-term objectives
| Objective | Averaging period | Long term objective | Date by which the long term objective should be met |
| Protection of human health | Maximum daily eight-hour mean within a calendar year | 120 μg/m3 | not defined |
| Protection ofvegetation | May to July AOT40 (calculated from 1 h values) | 6 000 μg/m3 ∙ h | not defined |