Stable tracer aerosol deposition measurements in a test chamber

Byrne, Mary; Goddard, A.J.H.; Lange, Christian; Roed, Jørn

doi:10.1016/0021-8502(95)00003-u

Cited by 70 publications

(61 citation statements)

References 16 publications

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“…Details of the tracer analysis methodology can be found elsewhere and are only brie y presented here (Byrne et al 1995;Lai et al 1999Lai et al , 2001a.…”

Section: Particle Generation and Aerosol Test Chambermentioning

confidence: 99%

“…Byrne et al (1995) employed a neutronactivatable monodisperse tracer aerosol to measure deposition velocity onto a smooth vertical wall of an 8 m 3 aluminum chamber under a single well-stirred ow condition. Thatcher and Nazaroff (1997) used monodisperse uorescent tracer particles to measure deposition velocity under natural convective conditions to irregular rough surfaces in a 1.8 m 3 aluminum chamber.…”

Section: Introductionmentioning

confidence: 99%

“…To address this, in the present work aerosol decay rates were determined for 4 particle sizes in a smooth-walled 8 m 3 test chamber, at a different fan speed to that studied by Byrne et al (1995) in the same chamber, so that the effect of fan speed on a size-speci c deposition rate could be observed. In addition, aerosol deposition on a regular array of three-dimensional roughness elements was determined in the 8 m 3 test chamber under 3 different well-stirred air ow conditions for a single particle size.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Studies of the Effect of Rough Surfaces and Air Speed on Aerosol Deposition in a Test Chamber

Lai¹,

Byrne²,

Goddard³

2002

Aerosol Science and Technology

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Understanding the fate of particles indoors is important for human health assessment because deposited particles, unless resuspended, cannot be inhaled. To complement studies in real buildings, where control of variables is often dif cult, an experimental test chamber facility (8 m 3 ) was designed to study particle deposition under well-stirred conditions using monodisperse tracer aerosol particles in the range of 0.7 to 5.4 ¹m. The use of neutronactivatable tracers facilitated simultaneous surface sampling and aerosol concentration decay measurements.Aerosol deposition on both smooth surfaces and regular arrays of three-dimensional roughness elements under 3 different air ow speeds was investigated in the test chamber. It was expected that the texture of the chamber surface would signi cantly in uence particle deposition, but some counterintuitive results were observed: under the lowest air ow condition and for the smallest particle size, particle deposition onto rough samples was found to be less than on the corresponding smooth surfaces.The ratio of particle deposition on rough surfaces relative to smooth surfaces increased with particle size and magnitude of airow. For the largest particle size and air ow speed, particle deposition on the rough surfaces exceeded that on the smooth surfaces by a factor of 3.

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“…Details of the tracer analysis methodology can be found elsewhere and are only brie y presented here (Byrne et al 1995;Lai et al 1999Lai et al , 2001a.…”

Section: Particle Generation and Aerosol Test Chambermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental Studies of the Effect of Rough Surfaces and Air Speed on Aerosol Deposition in a Test Chamber

Lai¹,

Byrne²,

Goddard³

2002

Aerosol Science and Technology

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“…Several studies on particle settling in indoor air suggested that sufficiently low air velocity is critical to ensuring particle deposition primarily by settling versus impaction (Byrne et al 1995;Lai and Nazaroff 2000;Thatcher et al 2002). The velocity measurements made near the bottom of the settling chamber indicated a mean air velocity of about 0.055 m/s, which was quite similar to measurement conditions (0.054 m/s) used by Thatcher et al (2002) to simulate particle deposition onto smooth surfaces.…”

Section: Chamber Mixing and Surface Deposit Uniformitymentioning

confidence: 66%

Development of an Aerosol System for Uniformly Depositing Bacillus Anthracis Spore Particles on Surfaces

Baron

Estill

Deye

et al. 2008

Aerosol Science and Technology

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After the anthrax incidents in October 2001, several techniques used for sampling surfaces for biological agents were found to be inadequately validated, especially at low surface loadings. Therefore a test chamber was developed to produce sample sets having targeted surface concentrations of dry biological agent simulant. Dry spore aerosols were initially dispersed into the chamber at relatively high air concentrations, and monitored in real time. The concentration decay (due to stirred settling and dilution) was measured and when the targeted air concentration was reached, the sampling surfaces were uncovered and exposed to the settling particles until >99% of the particles had settled. Multiple agar plates were used to estimate the true colony-forming-unit (CFU) surface concentration. The uniformity of surface loadings was limited by random deposition of small numbers of particles on the surfaces (Poisson distribution) and was characterized by how much greater the observed variability was than that predicted by Poisson statistics. The flow-enhanced powder mixture appeared to affect the spores' ability to grow on the agar medium. Three ways of analyzing the agar plates were used to evaluate the effect of spore coatings on viability and to differentiate between number of spore-containing particles and the number of spores. The presence of spore agglomerates resuspended by various sample handling activities in the chamber further increased the variability of deposited particles. Based on estimated airborne particle concentration, it was possible to predict mean agar plate concentrations within narrow confidence intervals (CI) at low (4.8 CFU, 95% CI 3.5-6.4), medium (20 CFU, 95% CI 17-23), and high (160 CFU, 95% CI 140-190) concentrations.

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“…In addition, the experimental variability of particle deposition onto indoor surfaces tends to be influenced by many environmental conditions, such as air flow intensity (Crump et al, 1983;Okuyama et al, 1986;Cheng, 1997), surface-to-air temperature difference (Thatcher et al, 1996), surface texture (Harrison, 1979;Byrne et al, 1995;Thatcher and Nazaroff, 1997), as well as surface-to-volume ratio and furnishings (Fogh et al, 1997;Thatcher et al, 2002). To illustrate the wide degree of variability, Figure 5.5 presents a comparison of the measured particle deposition coefficients from this work with other field and full-scale laboratory studies.…”

Section: Particle Deposition Coefficientsmentioning

confidence: 99%

Air pollutant penetration through airflow leaks into buildings

Liu

2002

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The penetration of ambient air pollutants into the indoor environment is of concern owing to several factors: (1) epidemiological studies have shown a strong association between ambient fine particulate pollution and elevated risk of human mortality; (2) people spend most of their time in indoor environments; and (3) most information about air pollutant concentration is only available from ambient routine monitoring networks. A good understanding of ambient air pollutant transport from source to receptor requires knowledge about pollutant penetration across building envelopes. Therefore, it is essential to gain insight into particle penetration in infiltrating air and the factors that affect it in order to assess human exposure more accurately, and to further prevent adverse human health effects from ambient particulate pollution.In this dissertation, the understanding of air pollutant infiltration across leaks in the building envelope was advanced by performing modeling predictions as well as experimental investigations. The modeling analyses quantified the extent of airborne particle and reactive gas (e.g., ozone) penetration through building cracks and wall cavities using engineering analysis that incorporates existing information on building leakage characteristics, knowledge of pollutant transport processes, as well as pollutant-2 surface interactions. Particle penetration is primarily governed by particle diameter and by the smallest dimension of the building cracks. Particles of 0.1-1 µm are predicted to have the highest penetration efficiency, nearly unity for crack heights of 0.25 mm or higher, assuming a pressure differential of 4 Pa or greater and a flow path length of 3 cm or less. Supermicron and ultrafine particles (less than 0.1 µm) are readily deposited on crack surfaces by means of gravitational settling and Brownian diffusion, respectively.The fraction of ozone penetration through building leaks could vary widely, depending significantly on its reactivity with the adjacent surfaces, in addition to the crack geometry and pressure difference. Infiltrating air can also travel through wall cavities, where the penetration of particles and ozone is predicted to vary substantially, depending mainly on whether air flow passes through fiberglass insulation. For ozone, its reactivity with the insulation materials is also an important factor. The overall pollutant penetration factor is governed by the flow-weighted average from all air leakage pathways. Large building leaks would strongly influence the overall penetration factor, because they permit much larger flow.The penetration of particles was also evaluated experimentally for three building leakage components that reflect different physical scales  individual building cracks, windows, and an entire house. Rectangular single straight-through cracks made of a variety of common building materials were used as building leak surrogates to examine particle penetration in the laboratory. The experimental results agree well with model predictions, suggesti...

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Stable tracer aerosol deposition measurements in a test chamber

Cited by 70 publications

References 16 publications

Experimental Studies of the Effect of Rough Surfaces and Air Speed on Aerosol Deposition in a Test Chamber

Experimental Studies of the Effect of Rough Surfaces and Air Speed on Aerosol Deposition in a Test Chamber

Development of an Aerosol System for Uniformly Depositing Bacillus Anthracis Spore Particles on Surfaces

Air pollutant penetration through airflow leaks into buildings

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