Directive 2008/50/EC of the European Parliament and of the CouncilShow full title

Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe

2.CriteriaU.K.

The following criteria shall be used for checking validity when aggregating data and calculating statistical parameters:

a

In cases where all possible measured data are not available, the following factor shall be used to calculate AOT40 values:

AOT40estimate = AOT40measured ×total possible number of hours (*)
number of measured hourly values
(*)being the number of hours within the time period of AOT40 definition, (i.e. 08:00 to 20:00 CET from 1 May to 31 July each year, for vegetation protection and from 1 April to 30 September each year for forest protection).
ParameterRequired proportion of valid data
One hour values75 % (i.e. 45 minutes)
Eight hours values75 % of values (i.e. six hours)
Maximum daily 8 hours mean from hourly running 8 hours75 % of the hourly running eight hours averages (i.e. 18 eight-hourly averages per day)
AOT4090 % of the one hour values over the time period defined for calculating the AOT40 valuea
Annual mean75 % of the one hour values over summer (April to September) and 75 % over winter (January to March, October to December) seasons separately
Number of exceedances and maximum values per month

90 % of the daily maximum eight hours mean values (27 available daily values per month)

90 % of the one hour values between 8.00 and 20.00 CET

Number of exceedances and maximum values per yearfive out of six months over the summer season (April to September)