Pressed wood products formaldehyde release rate

In China, formaldehyde emission of the pressed-wood products sold is generally high. A test showed that the average formaldehyde release rates of four kinds of typical wood-based panels, i.e., particle board, medium-density... 

A subpopulation with potentially high exposures to formaldehyde are residents of mobile homes due to the frequent use of pressed wood products and their low rate of air exchange (Wolff 1991). Members of the general population who come in contact with a large amount of unwashed permanent press fabrics treated with formaldehyde-releasing resins may also be exposed to high levels. 

Formaldehyde (CH2O) release was measured for seven types of consumer products pressed wood, urea formaldehyde foam materials, clothes, insulation, paper, fabric, and carpet. A modified Japanese Industrial Standard (JIS) desiccator test was used to measure release rate coefficients and to rank 53 products. Ten pressed wood products and five urea formaldehyde foam products showed the highest CH2O releases (1-34 mg m 2.day"b The remainder, representing all product types, had lower releases ranging from 680 yg m 2.day to nondetectable levels. In other studies, CH2O release was measured in a ventilated chamber for single samples of particle board, plywood, insulation, and carpet. 

As measured by the modified JIS desiccator procedure, pressed wood products had the highest release rate coefficients expressed as a function of surface area (Table IIA) of the various sample types tested. Release rate coefficients from urea formaldehyde foam products were comparable to those of pressed wood products (Table IIB). Products labelled substrate (sub 1, sub 2, and sub 6) were experimental foams. The drywall that had been placed next to the foams (Number 1, 2, or 3) for more than 1 week in a configuration similar to that in a building released a moderate amount of formaldehyde. 

Unwashed new clothing samples (Table IIC), fiberglass insulation products with formaldehyde resins (Table IID), paper products (Table HE), fabrics (cotton, nylon, olefin, and blended) (Table HF), and carpets (Table HG), had substantially 3 to > 100 fold) lower formaldehyde release rate coefficients, as measured by this method, than did pressed wood products or urea formaldehyde foams (1, 15). 

Pressed wood products and urea formaldehyde foam products had much higher release rates than those from most of the other products tested. Similar release rates have been observed by others (19). More than half of the products tested had very low release rate coefficients, and this included individual samples from six of seven of the types of products. Products equilibrated at 100% RH prior to the measurement were used to measure formaldehyde release. This equilibration may have removed a variable amount of formaldehyde (8, 14-17). 

The relative ranking for each type of product on the basis of rate of release of formaldehyde per unit surface area was pressed wood products z formaldehyde foam clothes z insulation products z paper products > fabric > carpet. Considering the surface area of each type of product likely to be present in houses and the relative release rate coefficients. 

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