A Pilot Study: The UNC Passive Aerosol Sampler in a Working Environment

Shirdel, Mariam; Wingfors, Håkan; Andersson, Britt M.; Sommar, Johan Nilsson; Bergdahl, Ingvar A.; Liljelind, Ingrid

doi:10.1093/annweh/wxx067

Cited by 3 publications

(8 citation statements)

References 15 publications

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“…Compared to the deposition model based solely on functions derived from physics, the model with

gives more weight to large particles and less to small particles. Based on our and others’ previous observations of low estimates for small particles ( Shirdel et al , 2017 ) and the fact that the wind speed was low in the present environments, an alternative expectation is that the only restriction from the mesh cap is the open area versus the closed area.…”

Section: Methodsmentioning

confidence: 56%

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Improving the UNC Passive Aerosol Sampler Model Based on Comparison with Commonly Used Aerosol Sampling Methods

Shirdel

Andersson

Bergdahl

et al. 2017

Annals of Work Exposures and Health

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ObjectivesIn an occupational environment, passive sampling could be an alternative to active sampling with pumps for sampling of dust. One passive sampler is the University of North Carolina passive aerosol sampler (UNC sampler). It is often analysed by microscopic imaging. Promising results have been shown for particles above 2.5 µm, but indicate large underestimations for PM2.5. The aim of this study was to evaluate, and possibly improve, the UNC sampler for stationary sampling in a working environment.MethodsSampling was carried out at 8-h intervals during 24 h in four locations in an open pit mine with UNC samplers, respirable cyclones, PM10 and PM2.5 impactors, and an aerodynamic particle sizer (APS). The wind was minimal. For quantification, two modifications of the UNC sampler analysis model, UNC sampler with hybrid model and UNC sampler with area factor, were compared with the original one, UNC sampler with mesh factor derived from wind tunnel experiments. The effect of increased resolution for the microscopic imaging was examined.ResultsUse of the area factor and a higher resolution eliminated the underestimation for PM10 and PM2.5. The model with area factor had the overall lowest deviation versus the impactor and the cyclone. The intraclass correlation (ICC) showed that the UNC sampler had a higher precision and better ability to distinguish between different exposure levels compared to the cyclone (ICC: 0.51 versus 0.24), but lower precision compared to the impactor (PM10: 0.79 versus 0.99; PM2.5: 0.30 versus 0.45). The particle size distributions as calculated from the different UNC sampler analysis models were visually compared with the distributions determined by APS. The distributions were obviously different when the UNC sampler with mesh factor was used but came to a reasonable agreement when the area factor was used.ConclusionsHigh resolution combined with a factor based on area only, results in no underestimation of small particles compared to impactors and cyclones and a better agreement with the APS’s particle size distributions. The UNC sampler had lower precision than the impactors, but higher than the respirable cyclone. The UNC sampler with area factor could be used for PM2.5, PM10 and respirable fraction measurements in this working environment without wind.

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“…Compared to the deposition model based solely on functions derived from physics, the model with

Section: Methodsmentioning

confidence: 56%

“…In a pilot study, the UNC sampler’s performance was compared to impactors in a mine ( Shirdel et al , 2017 ). It showed promising results for particles above 2.5 µm, but indicated large underestimations for PM 2.5 .…”

Section: Introductionmentioning

confidence: 99%

Improving the UNC Passive Aerosol Sampler Model Based on Comparison with Commonly Used Aerosol Sampling Methods

Shirdel

Andersson

Bergdahl

et al. 2017

Annals of Work Exposures and Health

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“…The previous two studies [11][12] where the samplers had been grounded, showed homogeneous distributions of particles on all collection surfaces. Static electricity could also be a possible explanation for the higher particle surface loading along the edge observed in this study, which might be due to an imbalance of charges leading the particles to the edge of the sampler where the electric field is strongest.…”

Section: Discussionmentioning

confidence: 83%

“…[5][6][7][8][9][10] There are two previous reports using the UNC sampler in the same working environment as in the present study. [11,12] These studies showed that stationary sampling with the UNC sampler was possible for PM 2.5 , respirable fraction, and PM 10 in the mine, which is an open-pit mine. In Shirdel et al, [12] a new model (area factor) was presented that did not consider the effects from wind because of the windless conditions in the mine.…”

Section: Introductionmentioning

confidence: 99%

Passive personal air sampling of dust in a working environment—A pilot study

Shirdel

Bergdahl

Andersson

et al. 2019

Journal of Occupational and Environmental Hygiene

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The aim of this study was to make a preliminary evaluation of the University of North Carolina passive aerosol sampler (UNC sampler) for personal air sampling of particles. Nine personal air samplings of respirable fraction were conducted in an open-pit mine, with pairwise UNC samplers and a respirable cyclone mounted on the chest of workers. UNC samples were analyzed with scanning electron microscopy (SEM) and to some extent energy dispersive X-ray spectroscopy (EDS). Respirable cyclone filter samples were weighed. Correlations and particle elemental compositions were described. Microscopic imaging of the collection surface showed that the particles were heterogeneously deposited across the surface of the UNC sampler. Collected particles were shaped as gravel particles and the resulting particle size distribution in air showed a peak at ca. 3 mm aerodynamic diameter, similarly to what has previously been reported from the same mine. The elemental composition indicated mineral origin. All correlations between the airborne mass concentrations from UNC samplers and respirable cyclones (Pearson ¼ 0.54 and Spearman ¼ 0.43) and between pairs of parallel UNC samplers (Pearson ¼ 0.55 and Spearman ¼ 0.67) were weak. The UNC sampler mass concentrations were approximately 30 times higher than those measured with the respirable cyclone. In conclusion, the UNC sampler, when used for personal sampling in a mine, provides a reasonable particle size distribution and the deposited particles appeared to be of mineral origin and not from textile or skin but the approximately 30-fold overestimation of mass concentrations when comparing with respirable cyclone sampling indicates that further improvements are necessary. Positioning of the sampler may be critical and moving the UNC sampler from the chest to e.g. the top of a helmet might be an improvement. Grounding of the sampler in order to avoid static electricity might also be useful. The UNC sampler should continue to be researched for personal sampling, as passive sampling might become a useful alternative to more laborious sampling techniques.

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“…However, the development of passive samplers for the collection of particles is more challenging. When the University of North Carolina passive air sampler was deployed 15 in a working mine, the airborne mass concentrations measured were only 24-35% (PM 2.5 ) and 39-58% (PM 10 ) of those measured at the same time by pumped sampling onto filters.…”

Section: Sampling Techniquesmentioning

confidence: 99%