Sets out a method for the preparation of reference test atmospheres for the determination of gaseous pollutants in ambient air, using permeation tubes. The procedure applies to the preparation of reference test atmospheres containing pollutant levels from 0.01 ppm to 5 ppm by volume (25 µg/m(sup)3(/sup) to 14 000 µg/m(sup)3(/sup)). A list of references is provided for information on various aspects of the permeation tube procedure for preparing reference test atmospheres.
