In this paper, a test method for evaluating the ability of adsorptive building materials to reduce the concentration of formaldehyde is examined. The authors developed a new method that uses a small chamber to test the suppressive effect of adsorptive building material on formaldehyde-emitting materials. Two small chambers are prepared, with the formaldehyde-emitting building material placed in one chamber, and a composite building material comprised of adsorptive building material and the same kind of the formaldehyde-emitting building material in the other. The formaldehyde emission factors of the two chambers are compared, and the equivalent ventilation rate Q_<ads> is calculated. This test method enables the indoor concentration reducing performance and the suppressive performance of the adsorptive building materials to be evaluated at the same time. The tests of the suppressive effect are examined using several kinds of adsorptive building materials, and accordingly the validity of the test method is verified.
