142 First or last date of monitoring period
The first and final dates of each monitoring period shall be stated on the forms.
A monitoring period shall consist of one or more measuring periods.
The measuring periods within one monitoring period should have the same length.
The minimum length of a measuring period is one week, the maximum one month.
When it is necessary to use different measuring periods during the year (e.g. weekly in summer and monthly in winter), two separate monitoring periods shall be identified and the results shall be reported separately on the forms.