Formaldehyde levels chamber

Heck et al. (1985) also determined the fate of inhaled formaldehyde in the rat. Male Fischer 344 rats were placed in a nose-only inhalation chamber and exposed to a 14.412.4 ppm air concentration of formaldehyde for 2 hours, were sacrificed, and a venous blood sample was collected and analyzed for formaldehyde content. Unexposed control rats had a mean formaldehyde blood level of 2.24 0.07 g/g of blood. Rats exposed to the 14.4 ppm air concentration of formaldehyde had blood concentrations of 2.25 0.07 g/g. These results indicate that during a nose-only inhalation exposure of rats to this concentration of formaldehyde, no significant quantities of formaldehyde could be detected in the blood. Lack of increase in blood formaldehyde levels indicates that only local absorption took place and absorbed formaldehyde was metabolized before reaching the bloodstream. In a similar study by Heck et al. (1983), Fischer 344 rats were exposed by inhalation to " C-formaldehyde at 8 ppm for 6 hours. Concentrations of total radioactivity (most likely as " C-formate) in the w hole blood and plasma were monitored for an additional 8 days. Plasma concentrations of " C increased over the exposure period, reaching a maximum at the termination of exposure. Plasma " C concentrations then declined slowly over the next few days. 

In another study on indoor formaldehyde emissions, quasi steady-state emission rates of formaldehyde from new carpets were measured in a large-scale environmental chamber (Hodgson et al. 1993). The emission rates were 57.2 and 18.2 g/nr/liour at 24 and 168 hours, respectively, after the start of each experiment. Similar results were observed in a Swedish study where indoor formaldehyde levels were found to be higher in homes having wall to wall carpeting (Norback et al. 1995). Another recent... 

Both the published literature and previously unpublished information obtained by the structural panel industry indicate that formaldehyde levels associated with panel products glued with phenol formaldehyde adhesives are extremely low. Large dynamic chamber tests which simulate conditions that might be found in tightly sealed residences indicate consistently that formaldehyde levels associated with freshly manufactured phenolic panel products are less than 0.1 parts per million. The data, as well as theoretical considerations, also indicate that the amount of formaldehyde contributed to the environment by phenolic panel products should rapidly approach zero as the small quantity of formaldehyde initially present in the products is released. 

The two-hour desiccator and Perforator test results shown in Table II are also indicative of very low formaldehyde levels for phenolic panels. As with most of the results obtained in dynamic chamber tests, the uniformity of these test results, both within and between studies, indicates that the various phenolic panel products are quite similar with respect to their emitting potential. 

Furnishing. The formaldehyde level in a room at actual conditions depends on several factors, and is not an arithmetical sum of various sources (10), (11). In order to estimate the contribution of formaldehyde emission from single pieces of furniture the test objects have been exposed in area to air volume proportions to which they can be found in a small room or a kitchen. The assumption that the formaldehyde level in the chamber and in the actual room is the same, is based on a theoretical model originally developed for particle boards (4). At constant climate the emission from a test object is determined of the relation between the loading factor and the air change rate. 

In the FTM-2 "Formaldehyde Test Method for Large Scale Test Chamber", the method allows a temperature correction factor to be applied to formaldehyde concentrations determined at temperatures other than the desired 25j 0.5 C. In addition, the states of Wisconsin and Minnesota allow temperature corrections of formaldehyde levels determined at temperatures other than 25 C for field complaint investigations. The temperature correction factors are based on the popular Berge Equation (25). 

Table VIII presents chamber data on underlayment particleboard, mobile decking particleboard, and industrial particleboard obtained from four different chambers identified A, B, C and D. A particleboard "set" is a specific production run of a particleboard type. The observed concentration is the formaldehyde level actually determined in the chamber for a specific loading and air change rate. "N" represents the air change rate (number per hour). The column labeled "L" is the loading (m2/m3) that the test was conducted. The column "N/L" ( m/hr) is the ratio of air change rate to the loading. Finally, the column labeled "Normalized Chamber Concentration" is the actual chamber concentration (first column) normalized to 0.3 ppm at N/L = 1.16. The 0.3 ppm chamber...

Table X. Two Product Loading Chamber Formaldehyde Levels...

All quality control tests and specimen conditioning are conducted under carefully controlled environmental conditions, i.e. temperature = 24 H3.5 C, 50h 5% relative humidity and a background formaldehyde level of less than 0.1 ppm. Ourselves as well as others have found that temperature effects on the quality control test values follow the same pattern observed in the large scale chamber (30). In short, the Berge temperature correction can be applied to the quality control test methods. 

Based on our experience, it appears that a quality control method which correlates to the chamber for a particular product type does not always work for all products. The only universal test method for all products is the large scale test chamber. A quick and reliable formaldehyde quality control test method is becoming more important as formaldehyde levels in the chamber fall below 0.15. A universal small scale test method (Q.C.) does not seem to exist at this time. However, the Small Scale Test Chamber may be the closest to fulfilling that purpose. 

Contamination of the reaetor by leaks and permeation of laboratory air contaminants is minimized by continuously flushing the enclosure that houses the reactors with purified air. NOx and formaldehyde levels in the enclosure before or dining irradiations were generally less than 5 ppb and PM coneentrations are below the detection limits of oin instrumentation. Introduction of contaminants into the reactor is also minimized by use of pressure control to assure that the reactors are always held at slight positive pressines with respect to the enclosure, so leaks are manifested by reduction of the reactor volume rather than dilution of the reaetor by enelosure air. The leak rate into the chamber was tested by injecting —100 ppm of CO into the enelosure and monitoring CO within the reactor. No appreciable CO (below the 50 ppb deteetion limit) was obtained for this experiment. 

HVAC Materials Ventilation duct liners also react with ozone forming formaldehyde, acetone and C5—Ci0 aldehydes. Morrison et al. (1998) subjected new and used duct liners, air filters, sealants, sheet metal and other HVAC materials to ozone in small chambers. They observed secondary emissions of C5—Ci0 aldehydes from a new duct liner, a neoprene gasket and duct sealants. They predicted that secondary emissions from these materials could increase indoor aldehyde concentrations to levels comparable with odor thresholds. As will be discussed later, soiled HVAC materials also generate secondary products. 

A limited number of sink effect studies have been conducted in full-sized environments. Tichenor et al. [20] showed the effect of sinks on indoor concentrations of total VOCs in a test house from the use of a wood stain. Sparks et al. [50] reported on test house studies of several indoor VOC sources (i.e., p-dichlorobenzene moth cakes, clothes dry-cleaned with perchloroethylene, and aerosol perchloroethylene spot remover) and they were compared with computer model simulations. These test house studies indicated that small-chamber-derived sink parameters and kj) may not be applicable to full-scale, complex environments. The re-emission rate (kj) appeared to be much slower in the test house. This result was also reported by other investigators in a later study [51]. New estimates of and were provided,including estimates of fca (or deposition velocity) based on the diffusivity of the VOC molecule [50]. In a test house study reported by Guo et al. [52], ethylbenzene vapor was injected at a constant rate for 72 h to load the sinks. Re-emissions from the sinks were determined over a 50-day period using a mass-balance approach. When compared with concentrations that would have occurred by simple dilution without sinks, the indoor concentrations of ethylbenzene were almost 300 times higher after 2 days and 7 times higher after 50 days. Studies of building bake-out have also included sink evaluations. Offermann et al. [53] reported that formaldehyde and VOC levels were reduced only temporarily by bake-out. They hypothesized that the sinks were depleted by the bake-out and then returned to equilibrium after the post-bake-out ventilation period. Finally, a test house study of latex paint emissions and sink effects again showed that... 

Manufactured Home Construction and Safety Standard, Air Chamber Test Method for Certification and Qualification of Formaldehyde Emission Levels," U.S. Code of Federal Regulations, Vol. 24, Part 3280.406, (U.S. Department of Housing and Urban Development), and F eral Register, Vol. 48, pg 37136-37195, 1983. 

The results of the study are summarized in Table III which provides 2-hour desiccator values and dynamic chamber values for both fresh and aired out panels. For most of the product types, both empty chamber and loaded chamber formaldehyde values are provided, the empty chamber values representing background measurements taken just before the chamber was loaded. These background levels represent residual formaldehyde present in the chamber from previous testing. 

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. 

Most products tested released only small amounts of formaldehyde. Only some pressed wood and urea formaldehyde foam insulation products released higher amounts of formaldehyde. Products tested in both ventilated chambers and unventilated desiccators released similar amounts of formaldehyde. Formaldehyde released by particle board was reabsorbed by the second product tested in a dynamic chamber. In a house this reabsorption might lower the room level of formaldehyde. 

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... 

Figure 2. During the testing the concentration of formaldehyde in the chamber will rise and stabilize at a steady state level.

The concept of a "baseline" originated during early large scale chamber testing when the test panels were loaded directly into the chamber with-out a conditioning period. The HCHO levels were monitored over a period of several days. During that interval, it was observed that there was a rapid decrease in HCHO levels over the first few days, followed by a interval of relatively slow decrease. This later interval usually exhibited a rate of formaldehyde decrease of 2 to 3% per day. At this point panels were said to be at "baseline" or steady-state formaldehyde equilibrium. Essentially,... 

Newton, L. "Formaldehyde Emissions from Wood Products Correlating Environmental Chamber Levels to Secondary Laboratory Tests" International Particleboard Symposium No. 16 Washington State University, Pullman, 1982. 

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. 

The various characterization experiments were used to derive the chamber characterization parameters and evaluate the ehamber eharaeterization model as discussed above. The single organic - NOx experiments were earried out to demonstrate the utility of the ehamber to test the mechanisms for these eompounds, for whieh data are available in other ehambers, and to obtain well-charaeterized meehanism evaluation data at lower NOx levels than previously available. The formaldehyde -i- CO - NOx experiments were carried out beeause they provided the most ehemieally simple system that model calculations indicated was insensitive to chamber effeets, to provide a test for both the basic mechanism and the light eharaeterization assigmnents. The aromatie - CO - NOx experiments were carried out because aromatic - NOx experiments were predieted to be very sensitive to the addition of CO, because it enhances the effects of radicals formed in the aromatic system on ozone formation. The ambient surrogate - NOx experiments were earried out to test the ability of the mechanism to simulate ozone formation under simulated ambient eonditions at various ROG and NOx levels. 

As discussed in our companion presentation (Carter, 2004a), the initial experiments carried out in the UCR EPA chamber consisted of a large number of ambient ROG surrogate -NOx experiments carried out at varying initial NOx and ROG levels. The ambient ROG surrogate composition was derived as discussed by Carter et al (1995) and consisted of a simplified mixture of designed to represent the major classes of hydrocarbons and aldehydes measured in ambient urban atmospheres, with one compound used to represent each model species used in current condensed lumped-molecule mechanisms. The eight representative compounds used were n-butane, n-octane, ethene, propene, trans-2-butene, toluene, m-xylene, and formaldehyde. The initial NOx levels varied from 2 to 300 ppb and the initial ROG levels varied from 0.2 to 4.2 ppmC. 

---