Dust Study design

The test apparatus consists of a natural gas burner to provide hot flue gas, a dust feeder designed by one of the authors, and a 9.68-cm ID cyclone (Figure 1). Calculations indicate that the residence time of particles in the hot flue gas is sufficient to heat the particles to the temperature of the flue gas at the cyclone entrance, and in any case the glass particles were subjected to the same conditions as the particles prepared from pilot plant deposits. We expect to obtain experimental confirmation of the adequacy of heating in a more detailed future study. 

As part of the project work plan, this protocol was tested in three case studies designed to match the three levels of vafidation, before preparation of the final version. The interlaboratory studies included analyses of i) selected natural and synthetic oestrogens and oestrogenic activity in wastewater, ii) pharmaceuticals in water and iii) brominated flame retardants in dust. The design of the interlaboratory studies, analytical protocols and final reports from the interlaboratory studies are available on the project web site. The final aim is flie implemenfation of the protocols in the fields of European standardisation and European legislation. To this purpose, negotiations will be initiated to launch New Work Item proposals at CEN level (see Eigure 8.1.5). 

The Dust Study was reasonably well designed, considering the complexity of the problem, and that the report provided information not available from any other source. The study indicated that the rule cleaning procedures reduced the residual lead (Pb) remaining after a renovation more than did the baseline cleaning procedures. Another positive aspect of the Dust Study was that it described deviations from the protocol when they occurred. 

The Dust Study, which is described elsewhere in the preamble, assessed the proposed work practices. As one component of the proposed work practices, the cleaning verification was evaluated in the Dust Study. It should be noted that the Dust Study was not designed specifically to evaluate the cleaning verification in isolation of the rest of the work practices. Unlike the earlier Disposable Cleaning Cloth Study that was intended to test the effectiveness of the use of the white glove test in isolation, the Dust Study was meant to evaluate the effectiveness of the proposed work practices, including cleaning verification. 

The instrumentation and methodology for testing soils in the laboratory similar to those used for dust. Preliminary results of the intercalibration study designed to measure differences between labs and instrument methods indicate that differences between methods was greater than differences between labs for the same method. 

The study shows, however, that the air curtain in the original design is bent off the wall due to the presence of the open oven with induced airflow inside the oven. This unexpected flow feature finally leads to a recirculation zone below the oven, and dust particles on the floor can be carried into the oven (class B quality). This effect was then also confirmed by smoke experiments in the real room and the existing ventilation system. 

It also specifies data requirements, assumptions, limitations, eventual type of critical review, and the report requirements. For example, a study could be done to select between one of two materials when developing a dust transport container for a baghouse filter. The intended audience may be the designers, the results being used to indicate which one of the two materials provides the lowest environmental impact. The system function may be to transport dust from the baghouse filter to a landfill site, and the functional unit may be one metric ton or m of dust. The system boundaries may be described by considering which processes are included and which are outside the system limits. 

Particulate Scrubbers Wet collectors, or scrubbers, form a class of devices in which a liquid (usually water) is used to assist or accomplish the collection of dusts or mists. Such devices have been in use for well over 100 years, and innumerable designs have been or are offered commercially or constructed by users. Wet-film collectors logically form a separate subcategory of devices. They comprise inertial collectors in which a film of liquid flows over the interior surfaces, preventing reentrainment of dust particles and flushing away the deposited dust. Wetted-wall cyclones are an example [Stairmand, Tram. lmt. Chem. Eng., 29,356 (1951)]. Wet-film collectors have not been studied systematically but can probably be expected to perform much as do equivalent dry inertial collectors, except for the benefit of reduced reentrainment. 

The simplest chemical compound that attracts adult deer ticks is carbon dioxide, which is in the breath of all mammals. In one experiment designed to study this effect, investigators first dusted 120 ticks with a fluorescent powder to render these tiny creatures more visible and then released them at various distances from a carbon dioxide-baited trap. After six days, the average distance a deer tick had crawled to reach the trap was 1.8 meters (a little less than 6 feet), or 600 body-lengths for a 3-millimeter tick. This is steady progress toward the carbon dioxide source but rather slow locomotion compared with many insects and even other ticks. 

The prototype cotton-dust analyzer used in the initial study was designed to measure dust smaller than 100 pm, whereas a vertical elutriator in a card room measures only the dust that is smaller than about 15 pm. Differences in particle size distributions of dust from various types of cotton would likely affect the relationship between the two dust measurements. Therefore, we deemed it necessary to investigate the use of sizing screens with smaller openings i.e., openings whose size approximated the maximum size of particles collected by a vertical elutriator. The purpose of this report is to describe additional modifications to the cotton-dust analyzer and to present data on the performance of the machine when 17-, 50-, and 100-pm sizing screens were used. 

Acute-Duration Exposure. Information is not available on the health effects of 1,2-diphenylhydrazine resulting from inhalation exposure in humans or animals. Because 1,2-diphenylhydrazine is a solid with a low vapor pressure at ambient temperatures, it is highly unlikely that inhalation exposure to this chemical in the vapor state would occur (Chapter 5). However, the possibility of inhalation exposure to dusts of 1,2- diphenylhydrazine either free or adsorbed to soil is conceivable. Therefore, acute studies of inhalation exposure to dusts of 1,2- diphenylhydrazine could be designed to provide information on possible toxic effects and exposure levels that cause effects. No studies were located regarding acute oral exposure in humans. The only pertinent acute exposure toxicity studies of... 

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