All trees and wood products emit small amounts of formaldehyde. An oak tree, for example, emits 0.009 parts per million (ppm) of formaldehyde. Any wood cut from that oak tree will also contain small amounts of formaldehyde.
The adhesive used to manufacture US trademarked plywood is phenol formaldehyde (phenolic) which does not release significant amounts of formaldehyde.
Under the harmonised European Standard for wood-based panels, EN 13986, Annex B, ‘wood-based panels glued with resins emitting either no formaldehyde or negligible amounts of formaldehyde after production as e.g. isocyanate or phenolic glue’ are to be classified as E1 (the lowest formaldehyde release class) without further testing.
APA plywood will be designated under the lowest E1 category for formaldehyde release without needing further testing. APA’s US PS 1 and PS 2 plywood have been tested to EN 717-1 and formaldehyde levels already meet the requirements for the E1 classification limit
On finished US trademarked plywood panels, independent tests confirm that formaldehyde emission levels rapidly approach zero as the panels age.
All available scientific data indicates that the maximum formaldehyde level associated with phenolic bonded wood panel products is about the same as background levels present in outdoor air in an urban environment.
Phenolic glue is manufactured from resins consisting of phenol formaldehyde polymers by reacting together measured amounts of phenol and formaldehyde under carefully controlled conditions. These polymers consist of ‘chains’ of phenol and formaldehyde which are chemically linked together to form polymer molecules. These molecules possess physical and chemical properties which are completely distinct from the properties of either phenol or formaldehyde i.e. these polymers are new chemical entities and not simply mixtures of phenol and formaldehyde.
Once formed, the phenolic polymers are extremely stable and do not break down into their original phenol and formaldehyde molecules. It is this stability which prevents the release of formaldehyde from panels containing this type of water proof adhesive.
Confusion over the different types of formaldehyde adhesive in use has led to concern over the possible release of formaldehyde from wood products and the possible effect on health. Formaldehyde-related problems have been associated with urea formaldehyde adhesives, commonly used in the manufacture of interior plywood.