Hygienic aspects of the use of pressed-wood products in residential buildings. Part I. The effect of particleboards ageing on release of formaldehyde.

Urea-formaldehyde-resins bounded particleboards (100 x 40 mm plates) each from a different manufactory plant, were stored at room temperature, with free access of air. In selected time intervals plates were placed in the climatic chamber for five days, and formaldehyde (CH2O) emission were determined. The conditions were as follows: loading factor 1 m2/m3, one air exchange per hour, air temperature of 25 degrees C and relative humidity (RH) 45%. During the 3 months following the production, CH2O emission decreased by more than 50%. During the next months of storing the emission decrease was slight. In the period of 1-3 years since the production, CH2O emission was 0.13-0.06 mg/m2/h, regardless of the amount of formaldehyde released in the first period after the production.