A Personal Cascade Impactor: Design, Evaluation and Calibration

Rubow, Kenneth L.; Marple, Virgil A.; Olin, John G.; McCawley, Michael

doi:10.1080/15298668791385174

Cited by 115 publications

(7 citation statements)

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“…To improve reproducibility, simplify sampling, and allow for easy comparison with planned in vitro dissolution rate studies, coating of the impaction substrates was not carried out in the present work except for a comparative measurement (Appendix B). Previous studies using the same type of impactor have concluded that some roll-off can be expected at impaction stages G and H (Rubow et al 1987). Cheng et al used the same type of impactor with coating applied on Stage A only.…”

Section: Uncertaintiesmentioning

confidence: 99%

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Uranium Aerosol Activity Size Distributions at a Nuclear Fuel Fabrication Plant

2020

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Inhalation of uranium aerosols is a concern in nuclear fuel fabrication. Determination of committed effective doses and lung equivalent doses following inhalation intake requires knowledge about aerosol characteristics; e.g., the activity median aerodynamic diameter (AMAD). Cascade impactor sampling of uranium aerosols in the breathing zone of nuclear operators was carried out at a nuclear fuel fabrication plant producing uranium dioxide via ammonium uranyl carbonate. Complementary static sampling was carried out at key process steps. Uranium on impaction substrates was measured using gross alpha counting and alpha spectrometry. Activity size distributions were evaluated for both unimodal and bimodal distributions. When a unimodal distribution was assumed, the average AMAD in the operator breathing zone at the workshops was 12.9–19.3 μm, which is larger than found in previous studies. Certain sampling occasions showed variable isotope ratios ( 234 U/ 238 U) at different impactor stages, indicating more than one population of particles; i.e., a multimodal activity size distribution. When a bimodal distribution (coarse and fine fraction) was assumed, 75–88% of the activity was associated with an AMAD of 15.2–18.9 μm (coarse fraction). Quantification of the AMAD of the fine fraction was associated with large uncertainties. Values of 1.7–7.1 μm were obtained. Static sampling at key process steps in the workshops showed AMADs of 4.9–17.2 μm, generally lower than obtained by breathing zone sampling, when a unimodal distribution was assumed. When a bimodal distribution was assumed, a smaller fraction of the activity was associated with the coarse fraction compared to breathing zone sampling. This might be due to impactor positioning during sampling and sedimentation of large particles. The average committed effective dose coefficient for breathing zone sampling and a bimodal distribution was 1.6–2.6 μSv Bq −1 for 234 U when Type M/S absorption parameters were assumed (5.0 μSv Bq −1 for an AMAD of 5 μm). The corresponding lung equivalent dose coefficient was 3.6–10.7 μSv Bq −1 (29.9 μSv Bq −1 for an AMAD of 5 μm). The predicted urinary excretion level 100 d after inhalation intake was found to be 13-34% of that corresponding to an AMAD of 5 μm. Uranium aerosols generated at a nuclear fuel fabrication plant using ammonium uranyl carbonate route of conversion were associated with larger AMADs compared to previous work, especially when sampling of aerosols was carried out in the operator breathing zone. A bimodal activity size distribution can be used in calculations of committed effective doses and lung equivalent doses, but parameters associated with the fine fraction must be interpreted with care due to large uncertainties.

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Section: Uncertaintiesmentioning

confidence: 99%

“…Impactor stage collection efficiencies were determined by Rubow et al (1987) using monodisperse aerosols. Early impaction stages are associated with lower collection efficiencies; thus, the impact on the overall uncertainty is greater when a large fraction of the activity is collected on early impaction stages.…”

Section: Uncertaintiesmentioning

confidence: 99%

Uranium Aerosol Activity Size Distributions at a Nuclear Fuel Fabrication Plant

2020

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“…Personal cascade impactors are also available to obtain the size distribution of a particulate exposure [20, 21]. Cascade impactors consist of sequential impactors in series with decreasing cutoff sizes.…”

Section: Approaches For Estimating Pm Massmentioning

confidence: 99%

New Methods for Personal Exposure Monitoring for Airborne Particles

Koehler

Peters

2015

Curr Envir Health Rpt

107

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Airborne particles have been associated with a range of adverse cardiopulmonary outcomes, which has driven its monitoring at stationary, central sites throughout the world. Individual exposures, however, can differ substantially from concentrations measured at central sites due to spatial variability across a region and sources unique to the individual, such as cooking or cleaning in homes, traffic emissions during commutes, and widely varying sources encountered at work. Personal monitoring with small, battery-powered instruments enables the measurement of an individual’s exposure as they go about their daily activities. Personal monitoring can substantially reduce exposure misclassification and improve the power to detect relationships between particulate pollution and adverse health outcomes. By partitioning exposures to known locations and sources, it may be possible to account for variable toxicity of different sources. This review outlines recent advances in the field of personal exposure assessment for particulate pollution. Advances in battery technology have improved the feasibility of 24-hour monitoring, providing the ability to more completely attribute exposures to microenvironment (e.g., work, home, commute). New metrics to evaluate the relationship between particulate matter and health are also being considered, including particle number concentration, particle composition measures, and particle oxidative load. Such metrics provide opportunities to develop more precise associations between airborne particles and health and may provide opportunities for more effective regulations.

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“…Although collection efficiency ‫)ܧ(‬ depends on particle size, it is not easily related to the Stokes number [14]. Thus, the actual collection efficiency curves are usually determined experimentally by measuring responses of monodisperse calibration aerosols [15][16][17][18][19][20][21][22][23][24][25][26]. In this work, the following general expression was used:…”

Section: Mathematical Descriptionmentioning

confidence: 99%

A modular tool for analyzing cascade impactors data to improve exposure assessment to airborne nanomaterials

Bau

Witschger

2013

J. Phys.: Conf. Ser.

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Cascade impactors are widely used to provide particle size distributions for the study of aerosols in workplaces and ambient air. In the frame of exposure assessment to airborne particles, one of their main advantages is the possibility to perform further off-line analysis (e.g. electron microscopy, physical-chemical characterization by XRD, ICP-MS, etc.) on the collected samples according to particle size. However, the large channel width makes the particle size distributions not enough size-resolved. Furthermore, in spite of the sharpness of the collection efficiency curves, the existence of an overlap between stages renders data interpretation difficult. This work aim was to develop a modular program allowing the inversion of data stemming from cascade impactors based on the mass (or any quantity) collected on each impaction stage. Through a precise description of the collection efficiency curves of the different stages, the software provides a continuous curve (from 100 to 1000 points) using the Markowski method, and more particularly the Twomey iterative algorithm, according to several publications about inverse problems in cascade impactors. An additional option consists in determining the experimental error at each point of the inverse curve, performed by realizing several consecutive inversions. The inversion procedure was first tested and optimized for the case of the SIOUTAS personal sampler. Validation of the calculation was performed considering theoretical aerosols. Then, the software was used for two sets of data obtained during field measurement campaigns.

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A Personal Cascade Impactor: Design, Evaluation and Calibration

Cited by 115 publications

References 0 publications

Uranium Aerosol Activity Size Distributions at a Nuclear Fuel Fabrication Plant

Uranium Aerosol Activity Size Distributions at a Nuclear Fuel Fabrication Plant

New Methods for Personal Exposure Monitoring for Airborne Particles

A modular tool for analyzing cascade impactors data to improve exposure assessment to airborne nanomaterials

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