4. Nature and assessment of pollution—
(a)concentrations observed over previous years (before the implementation of the improvement measures);
(b)concentrations measured since the beginning of the project; and
(c)techniques used for the assessment.
4. Nature and assessment of pollution—
(a)concentrations observed over previous years (before the implementation of the improvement measures);
(b)concentrations measured since the beginning of the project; and
(c)techniques used for the assessment.