Mobile homes, formaldehyde emission

Figure 1. Diurnal variations of formaldehyde air levels in a mobile home. Solid curve is calculated from product emission data dotted curve is observed (33). ...

The HUD product standards are tied to the objective of providing a 0.4 ppm ambient target level in new manufactured homes. The hypothesis that product emission standards can be related to ambient formaldehyde levels was tested in a HUD sponsored project (7.) that involved constructing four experimental mobile homes and comparing home observed formaldehyde levels with... 

G. Gramp, W. Groah. "Evaluation of the relationship between formaldehyde emission from particleboard mobile home decking and hardwood plywood wall paneling as determined by product test methods and formaldehyde levels in experimental mobile homes." U.S. Dept. of Housing and Urban Development, 1982. 

The monitoring and toxicological studies of formaldehyde exposure, as well as studies on the emission of this chemical from wood products generate large numbers of samples to be analyzed. Furthermore, it is necessary to monitor the emissions on a routine basis during production to ensure that the material continues to release low level of formaldehyde. In homes, particularly in mobile homes, the amount of formaldehyde release depends on the construction technoloy, ventilation, indoor temperature and relative humidity, and age, structure and porosity of building materials. It is, therefore, necessary to study the emislon of formaldehyde from wood products as a function of these parameters. 

During the past decade, urea formaldehyde and phenol formaldehyde resin binders have contributed greatly to the progress of wood industries. Formaldehyde is widely used as a major component in the production of building materials, such as particleboard and plywood, and in urea formaldehyde foam insulation. However, the emissions of formaldehyde from these products create considerable concerns not only in the working environments but also in residences, mobile homes, and office buildings. These concerns have also been stimulated by reports on the health effects and carcinogenicity associated with formaldehyde exposure. 

These test chambers can be incorporated to the enzymatic methods for formaldehyde determination. Formaldehyde emissions of a product, or mix of products, to the ambient air can be collected in distilled water or 1% sodium bisulfite as the absorbing solution. After collection, formaldehyde samples are analyzed as described above. In the mobile home simulator test method (2J, double or triple impingers, which are placed in series, should be used in order to collect all of the formaldehyde vapor. The test conditions should simulate the actual environment. Several factors such as temperature and relative humidity of the system including the specimens and background of formaldehyde in the test chamber, affect the precision and accuracy of the results. It has been shown that a 7 C change in temperature doubles the emission level (L). The temperature of the test chamber should be... 

The U.S.Department for Housing and Urban Development s rule 3280.308 established formaldehyde emission standards for particleboard and hardwood plywood paneling used in mobile homes. These standards took effect February 11, 1985. The certification program under this rule requires each manufacturer to develop a quality control in-plant testing program that relates to tests conducted in a large scale environmental chamber. 

The first was the Clayton Study (29) sponsored by H.U.D. in which four mobile home units were constructed with wood products of known formaldehyde emission characteristics as determined in the large scale chamber. The other three studies were from an association and two industrial laboratory chambers working independently of each other. Essentially, all four studies came to the same conclusion -it is possible to predict chamber concentrations from a combination of two formaldehyde emitting products. 

Singh Walcott, J. St. Pierre, C. Ferrel, T. Garrison, S. Groah, w. "Evaluation of the Relationship Between Formaldehyde Emissions from Particleboard Mobile Home Decking and Hardwood Plywood Wall Paneling Determined by Product Test Methods and Formaldehyde Levels in Experimental Mobile Homes" Clayton Environmental Consultants, Inc., Report, Prepared on Contract No. AC-5222, H.U.D., March, 1982. 

Examples of situations that have led to complaints are energy-efficient homes in Russia, Sweden and Holland school houses in Germany, Czechoslovakia and Switzerland portable temporary offices and classrooms in Canada and mobile homes in the US. Mobile homes constitute a special situation, because he e residences contain UF-bonded products in a load ratio of 1.1 rn /in and recent HUD regulations allow formaldehyde levels of new homes to reach 0.4 ppm under standard conditions of 25 l. Such levels are a multiple of conventional homes. Such levels allow little margin for improper or defective products, and for emission increases due to warm climates (. ... 

The incidence of perceptible formaldehyde in homes, offices and schools has caused widespread uncertainty about the safety of living with formaldehyde. This uncertainty was enhanced by the large scale installation of urea formaldehyde foam insulation (UFFI) because a substantial part of this material was made from small scale resin batches prepared under questionable quality control conditions, and was installed by unskilled operators (10). The only reliable way to avoid such uncertainty is to know the emission rate of products and develop a design standard that allows prediction of indoor air levels. The first and most important step in this direction was achieved with the development and implementation of material emission standards. As indicated above, Japan led the field in 1974 with the introduction of the 24-hr desiccator test (6), FESYP followed with the formulation of the perforator test, the gas analysis method, and later with the introduction of air chambers (5). In the U.S. the FTM-1 (32) production test and the FTM-2 air chamber test (33) have made possible the implementation of a HUD standard for mobile homes (8) that is already implemented in some 90% of the UF wood production (35), regardless of product use. 

---