Introduction
Formaldehyde is a colourless, strong-smelling gas. It is widely used to manufacture building materials and numerous household products. Its most significant use in indoor environment is as an adhesive resin in pressed wood products.
Gas emission rate affects its equilibrium state (in more scientific term “steady state”) e.g. it will take longer time to reach a steady state for higher emission rate of formaldehyde by a substance (e.g. wood product) while lower emission rate will reach steady state at a relatively faster time. Formaldehyde emission from wood products reduces after some period of time in use thus, causing declined concentration from the steady state.
Factors affecting formaldehyde emission rate from wood products
Resin content: The type of formaldehyde resin used affects wood product formaldehyde emission rate. There are two types of formaldehyde resins: urea formaldehyde (UF) and phenol formaldehyde (PF). Products made of urea formaldehyde can release formaldehyde gas; products made of phenol formaldehyde generally emit lower levels of the gas.
Resin concentration:
Press temperature and Press time: Within panels hot-pressed using the UF resin, panels pressed at the lower temperature, longer pressing time condition emit less formaldehyde while PF resin formaldehyde emission will be lowered under the higher temperature, shorter pressing time conditions.
Moisture content: Wood is a hygroscopic material and has ability to exchange its moisture content with air. Formaldehyde emissions correlated well with the amount of water vapour collected for panels pressed with UF, but not for panels pressed with PF resin. An additive in the PF resin will decrease formaldehyde emissions during pressing of panels with PF.
Panel density: Formaldehyde emission decreases with increase in panel density.
Health effects
Health effects resulting from formaldehyde exposure include: Cancer; watery eyes; burning sensations in the eyes, nose and throat; nausea; coughing; chest tightness; wheezing; skin rashes; and other irritating effects
Manufacturers’
Manufacturers of building materials and furniture are responsible for taking reasonable prudent precautions to insure composite wood products used in the manufacture of building materials and furniture are compliant to formaldehyde emission standards specified in The Airborne Toxic Control Measure to Reduce Formaldehyde Emissions from Composite Wood Products (ATCM) 93120.2(a).
Consumers’ responsibility
It is the responsibility of consumers to purchase building materials and furniture labelled as formaldehyde low-emitting product based on ATCM 93120.2(a) standard.
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