This part of ISO 16000 specifies a general laboratory test method for evaluating the reduction of formaldehyde concentrations by sorptive building materials. This method applies to boards, wallpapers, carpets, paint products, and other building materials. The sorption of formaldehyde can be brought about by adsorption, absorption and chemisorption. The performance of the material with respect to its ability to reduce the concentration of formaldehyde in indoor air is evaluated by measuring sorption flux and saturation mass per area. The former directly indicates material performance with respect to formaldehyde concentration reduction at a point in time; the latter relates to the ability of a product to maintain that performance. The method specified in this part of ISO 16000 employs formaldehyde-spiked supply air to determine the performance of building materials in reducing formaldehyde concentrations. The characteristics of formaldehyde sorption depend greatly on humidity. Formaldehyde is less stable in air than other volatile organic compounds (VOCs), so it has to be tested on its own. This part of ISO 16000 is based on the test chamber method specified in ISO 16000-9. Sampling, transport and storage of materials to be tested and preparation of test specimens are specified in ISO 16000-11. Air sampling and analytical methods for the determination of formaldehyde are specified in ISO 16000-3, which is part of the complete procedure.