particulate matter". The measurement principle
is based on the collection on a filter of the PM10 fraction of ambient
particulate matter and the gravimetric mass determination.

A Member State may use any
other method which it can demonstrate gives results equivalent to the above
method or any other method which the Member State concerned can demonstrate
displays a consistent relationship to the reference method. In that event the
results achieved by that method must be corrected by a relevant factor to
produce results equivalent to those that would have been achieved by using the
reference method.

Each Member State must inform
the Commission of the method used to sample and measure PM10. The Commission
must as soon as possible carry out intercomparison exercises for PM10 sampling
and measurement methods in order to provide information for the review of this
Directive in accordance with Article 10.

V. Provisional reference
method for the sampling and measurement of PM2,5

The Commission will produce
guidelines, in consultation with the committee referred to in Article 12 of
Directive 96/62/EEC, for an appropriate provisional reference method for the
sampling and assessment of PM2,5 by 19 July 2001.

A Member State may use any
other method which it considers suitable.

Each Member State must inform
the Commission of the method used to sample and measure PM2,5. The Commission
must as soon as possible carry out intercomparison exercises for PM2,5 sampling
and measurement methods in order to provide information for the review of this
Directive in accordance with Article 10.

VI. Reference modelling
techniques:

Reference modelling
techniques cannot be specified at present. Any amendments to adapt this point
to scientific and technical progress must be adopted in accordance with the
procedure laid down in Article 12(2) of Directive 96/62/EC.