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Parallel personal sampling was carried out with the open-face filter cassette and the IOM sampler for inhalable dust for nine types of organic dust. Parallel samples numbering 749 were obtained from 152 plants. Extremely large values and outliers were disregarded, and the remaining data for each type of dust were divided into subsets according to type of product or work task, and analyzed with the aid of linear regression. The coefficient of regression for each subset ranged between 0.2 and 0.7. Hypothetical occupational exposure limits (OELs) for inhalable dust were calculated based on the linear relation obtained between the dust concentrations measured with the open-face filter cassette and the IOM sampler. The fraction of person days with time-weighted average (TWA) concentrations exceeding the calculated hypothetical OELs for inhalable dust was obtained from the distribution of measured TWA inhalable dust concentrations. Based on the results of this study and the difference in sampling efficiency for large particles between the two samplers, it was concluded that the numerical value of the OEL for inhalable dust may be set at approximately twice the numerical value of the corresponding limit value for "total dust." Additional consideration of recently discovered health effects, and technical and economical factors may result in other numerical values of future OELs for inhalable dust.

Elemental carbon has been proposed as a marker of diesel particulate matter. The objective of this study was to investigate if water-soluble carbonaceous compounds could be responsible for positive bias of elemental carbon using NIOSH Method 5040 with a thermo-optical carbon transmittance analyzer. Filter samples from eight different aerosol environments were used: pure diesel exhaust fume with a high content of elemental carbon, pure diesel exhaust fume with a low content of elemental carbon, pure biodiesel exhaust fume, pure woodsmoke, an urban road tunnel, an urban street canyon, an urban background site, and residential woodburning in an urban area. Part of each filter sample was analyzed directly with a thermo-optical carbon analyzer, and another part was extracted with water. This water-soluble extract was filtered to remove particles, spiked onto filter punches, and analyzed with a thermo-optical transmittance carbon analyzer. The ratio of elemental carbon in the water-soluble extract to the particulate sample measurement was 18, 12, and 7%, respectively, for the samples of pure woodsmoke, residential woodburning, and urban background. Samples with diesel particulate matter and ambient samples with motor exhaust detected no elemental carbon in the water-soluble extract. Since no particles were present in the filtered water-soluble extract, part of the water-soluble organic carbon species, existing or created during analysis, are misclassified as elemental carbon with this analysis. The conclusion is that in measuring elemental carbon in particulate aerosol samples with thermo-optical transmittance analysis, woodsmoke, and biomass combustion samples show a positive bias of elemental carbon. The water-soluble EC could be used as a simple method to indicate other sources, such as wood or other biomass combustion aerosol particles.

agreed on common definitions for health-based sampling conventions for the inhalable, thoracic, and respirable aerosol fractions. (1)(2)(3) The physiological data on the relevant knowledge of how large a fraction of particles (of different sizes) penetrate into and/or deposit in various compartments of the human respiratory tract particle were summarized by Soderholm. (4) These sampling conventions are plotted in Figure 1.The sampling convention for inhalable dust was based on research on mannequins equipped with breathing machines and filters that collected the aerosol aspirated through a "mouth." The experiments were carried out in wind tunnels for wind speeds in the range 1-9 m/sec, and the mannequins were rotated during the experiment. (5,6) The range of wind speeds was based on what was of interest to the mining industries. The aspiration efficiency of the rotated mannequin with respect to particle size can be called the "inhalability," but this term is not used in any of the three standards referred to above. Based on the experiments, "inhalability" was defined as direction averaged and was to be independent of wind speed in the range 1-4 m/sec. The convention was truncated at 100 µm, as the underlying experiments for larger particle sizes had turned out to be exceedingly difficult to perform. Neither the "Inhalable" curve in Figure 1, nor "Thoracic" or "Respirable" depicts the spread of the underlying data. Most data on inhalability are found within a band of ±0.10.A sampling convention defines the sampling efficiency vs. aerodynamic diameter for an ideal sampler. However, it cannot accurately reflect the fraction of particles deposited in the respiratory tract region of interest, as the deposition depends on worker-related parameters (work rate, worker fitness, nose vs. mouth breathing, etc.) and workplace-related (air speed and direction, proximity to source, etc.) that cannot all be brought into a grand average describing a single, ideal sampler collection efficiency curve. Thus, a sampling convention reflects a general agreement as to how large a fraction of particles with a specified size shall be included in collected samples. A sampling convention is intended to compare a sample against a standard airborne concentration only when that standard concentration has been established through epidemiologic or other studies that link airborne concentrations measured by that sampling convention to health effects. It is not intended to be used for the measurement of the amount of particles deposited within any specific worker during his/her work.From the standardized sampling convention, CEN went on to standardize a test procedure and the performance criteria for an aerosol sampler intended to collect any of the three aerosol fractions. (7) For samplers of the inhalable aerosol fraction, the test experiments were to be carried out with the tested sampler mounted on a nonbreathing mannequin in a wind tunnel. The CEN performance test and performance requirements were evaluated in a pan-European test on availabl...