Determination of partition and diffusion coefficients of formaldehyde in selected building materials and impact of relative humidity.

The partition and effective diffusion coefficients of formaldehyde were measured for three materials (conventional gypsum wallboard, “green” gypsum wallboard, and “green” carpet) under three relative humidity (RH) conditions (20%, 50%, and 70% RH). The “green” materials contained recycled materials and were friendly to environment. A dynamic dual-chamber test method was used. Results showed that a higher relative humidity led to a larger effective diffusion coefficient for two kinds of wallboards and carpet. The carpet was also found to be very permeable resulting in an effective diffusion coefficient at the same order of magnitude with the formaldehyde diffusion coefficient in air. The partition coefficient (K ma) of formaldehyde in conventional wallboard was 1.52 times larger at 50% RH than at 20% RH, whereas it decreased slightly from 50% to 70% RH, presumably due to the combined effects of water solubility of formaldehyde and micro-pore blocking by condensed moisture at the high RH level. The partitio...