Total dust measurements

For the evaluation of total dust concentration, the various models of sampHng heads are furnished with porous filters of different sizes, usually made from special papers consisting of polymeric materials like cellulose acetate and polycarbo- 

As with all gravimetric determinations, the conditioning of the filter media plays an important role. If the filters are not processed immediately after sampling, major errors may occur. This includes detemining tare and gross weight at the same air humidity. Tempering in an autoclave for several hours is especially recommended. 

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As an example, the measurement data on inorganic total dust collected in con ventional factories and benchmark factories is shown in Fig. 6.9. 

By exclusion or subtraction it is meant that the explicitly-determined value for Xg may be subtracted from the aggregate or total respirable dust measured in the workplace. Logic for subtraction necessitates the assumption that the x, component does not contain the causative agent for byssinosis. Determinations need to be made biannually for each process in case the exclusion or subtraction strategy is allowable and used. 

In the other study. X-ray fluorescence spectroscopy was used to analyze trace element concentrations by observing dusts on 37 ram diameter cellulose acetate filters (20). Twenty-three elutriator and twenty-three area samples from 10 different bales of cotton were analyzed. The average fraction of total dust accounted for by the elements analyzed was 14.4% amd 7.6% for vertical elutriator and area samples, respectively. Although the variation in absolute quantity of atn element was high, the relative abundance of an element was consistent for measurements within a bale. Averaged over all the samples analyzed, calcium was the most abundant element detected (3.6%), followed by silicon (2.9%), potassium (2.7%), iron (1.1%), aluminum (1.1%), sulfur (1.0%), chlorine (0.8%) and phosphorous (0.6%). Other elements detected in smaller aunounts included titanium, manganese, nickel, copper, zinc, bromine, rubidium, strontium, barium, mercury amd lead. 

Similar phenomena has been observed by others (43). Thus, much of the dust measured in total or elutriated s2unples of cotton dusts arises from the spray drying of the humidifier water. 

Under normal conditions of exposure borates are primarily irritants of the skin and respiratory system. Workers exposed to anhydrous sodium tetraborate complained of nasal irritation, nose bleeds, cough, shortness of breath, and dermatitis. Exposure levels were not measured, but total dust levels were described as high enough to obscure visibility in production areas. In another study of borax workers, symptoms of acute respiratory irritation including dryness of the mouth, nose, or throat, cough, nosebleeds, and shortness of breath were related to exposures of 4mg/m or more. ... 

Dust from paved and unpaved roads is the most predominant source in Portland. Accurate emissions data is critical to the model s ability to account for all of the measured mass, as well as to the development of a successful strategy. Although the CMB model cannot distinguish between dust emissions from paved and unpaved roads, it can typically assign total dust impacts to within a 5-6% uncertainty. Leaded automotive tailpipe exhaust was selected because it can be accurately estimated by CMB and is the third most abundant contributor to the annual particulate mass, after road dust and vegetative burning. 

Weighting of Occupational Histories—If a worker has been employed in several occupations over a period of years, some measure of his total dust exposure becomes necessary. This is particularly true when medical findings must be correlated with the amount of the workers exposure. Pneumoconiosis is the result of prolonged exposure to dust, and... 

Since the induction of pulmonary disease may be the result of a foreign protein reaction, rather than measuring a workers total dust exposure as is presently done, it may be more advantageous to examine the ccmponent of that exposure that consists of protein bearing particles. The purpose of this study was to demonstrate a method for determining particulate protein concentrations and... 

It is generally very difficult to measure total gas column densities through a cloud, while it is relatively straightforward to measure die extinction (essentially optical depth) due to dust at some wavelength. The extinction is related to the total dust column density via a dust model, including a particle size distribution. These dust models are typically not unique, hence the additional constraint from the elemental abundances of dust constituents, in particular Si and Fe. Therefore, the conversion factor between the two is an important number, and significant efforts have been directed toward its measurement. 

This method clearly gives an exaggerated figure for dustiness by measuring the total dust contents elutriable. In normal factory handling, only a fraction of the potentially airborne dust content is liberated. 

Emission factors for particulate matter are displayed in Figure 3.7. These are based on measurements of total dust, PMio (particles less than or equal to 10pm) and PM2 5 (particles less than or equal to 2.5pm). Note that by definition PMio includes PM2.5. [141, CERP, 1999]... 

Total dust was measured on top of the regenerators and behind the regenerators. Comparative measurements were carried out at other furnace with same size and running under similar conditions... 

In the last equation excess K" was excluded since its concentration was too small when compared to the other components. Thus on the average sulfate from pollution is estimated to be about 19.0% of the total sulfate measured in rain, the rest is divided between sea salt (19.4%) and soil components (61.6%). Soil minerals in Israel and Saharan dust storms... 

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