The use of wood based panels is widespread due to the fact that most of the furniture is made from these products. Almost 95 % of wood based panels are made using polycondensational adhesives. Formaldehyde is a major component in these adhesives, and any unbound formaldehyde will emit from wood based panels that have been made using the aforementioned adhesives. The emission rate of formaldehyde depends on the type and amount of adhesive used, density of the panel and the moisture content of the product or the environment surrounding it. For the experiment we took commercially available 3-layered particle boards and exposed them to different levels of humidity at a constant temperature of 20 °C. The levels of humidity ranged from absolutely dry to 87 %. The reference humidity level was at 65 %. The emission of free formaldehyde was measured using the WKI flask method. We also looked at what happens to formaldehyde emissions after a prolonged period of time. We found that both high (87 %) and extremely low humidity increased the emission rate of free formaldehyde. After a prolonged period of time, the free formaldehyde emissions decreased and eventually equalized in all samples.