Experimental studies on diffusion coefficients of volatile organic compounds for building materials

Many studies present construction and cladding materials as main sources of indoor air pollution, particularly of volatile organic compounds (VOC). Besides, the contribution of those materials cannot be always seen as just the result of a one-way emission: There are important interactions of physic-chemistry nature with other pollutants and humidity in the air and, also, the potential effect of adsorption/desorption of some pollutants on the surfaces. The development of mathematical models for the prevision of the concentration of pollutants in real situations requires the previous study of the behaviour of the materials vs pollutants to quantify experimentally the parameters involved, namely, the diffusion coefficients and partition coefficients. The available data in the literature for those coefficients is still scarce and, in general, of highly dispersed values. A number of experimental tests of diffusion of specific VOCs (m-xylene and n-octane) were made using the cup method for some materials or products currently used in buildings (carpet, gypsum and gypsum board, concrete, cork flooring material without finishing). The results, compared with data from other laboratories in Europe show to be of the same order of magnitude.