Modeling pollutant penetration across building envelopes

Liu, De-Ling; Nazaroff, William W.

doi:10.1016/s1352-2310(01)00218-7

Cited by 234 publications

(184 citation statements)

References 22 publications

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“…In recent studies (Liu and Nazaroff 2001, Mosley et al 2001, Vette et al 2001, penetration factors of particles within range of 0.5-2.5 µm have been between 0.5 and 1 depending on the dimensions of studied cracks. These results cover the size distribution of fungal spores; and the peak of spores of 1-2 µm seems to be very capable for penetration if the crack height is higher than 0.1 mm (Liu and Nazaroff 2003).…”

Section: Discussionmentioning

confidence: 99%

“…However, there is only a limited number of studies about structures typically used in buildings. Liu and Nazaroff (2001) predict by a simulation model that penetration through mineral wool insulation is negligible. In reality, the mineral wool insulation is seldom perfectly installed, and timber frame structures are in respect of particle transport a combination of cracks, surface contacts and mineral wool.…”

Section: Crawl Space Base Floor Outdoor Air Flow Outdoor Air Flowmentioning

confidence: 98%

“…Mosley et al (2001) have found that at a pressure of 5 Pa 40% of 2 µm particles and <1% of 5 µm particles penetrate through horizontal slits of height 0.508 mm. In a study (Liu and Nazaroff 2001) particles of 0.1-1.0 µm are predicted to have the highest penetration efficiency, nearly unity for crack heights of 0.25 mm or larger at pressure difference of ≥4 Pa. These results are important since the peak of the size distribution of fungal spores is often between 1-3 µm being very suitable for penetration.…”

Section: Crawl Space Base Floor Outdoor Air Flow Outdoor Air Flowmentioning

confidence: 99%

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Fungal spore transport through a building structure

Airaksinen¹,

Kurnitski²,

Pasanen

et al. 2004

Indoor Air

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The study carried out laboratory measurements with a full-scale timber frame structure to determine penetration of inert particles with size distribution from 0.6 to 4 µm and spores of Penicillium and Cladosporium through the structure. Pressure difference over and air leakage through the structure were varied. Measurements at moderate pressure differences resulted in the penetration factors within the range of 0.05 to 0.2 for inert particles, and indicated also the penetration of fungal spores through the structure. The measurements showed that the penetration was highly dependent on pressure difference over the structure but not on holes in surface boards of the structure. The results show that surface contacts between the frames and mineral wool may have a significant effect on penetration. The penetration was approximately constant within particle size rage of 0.6-2.5 µm, but particles with diameter of 4.0 µm did not penetrate through the structure at all even at a higher-pressure difference of 20 Pa, except in the case of direct flow-path through the structure. Results have important consequences for practical design showing that penetration of fungal spores through the building envelope is difficult to prevent by sealing. The only effective way to prevent penetration seems to be balancing or pressurizing the building. In cold climates, moisture condensation risk should be taken into account if pressure is higher indoors than outdoors. Determined penetration factors were highly dependent on the pressure difference. Mechanical exhaust ventilation needs a special consideration as de-pressurizing the building may cause health risk if there is hazardous contamination in the building envelope exists. PRACTICAL IMPLICATIONSMeasurements at moderate pressure differences allowed determining penetration factors within the range of 0.05 to 0.2 for inert particles in a size range of 0.6-2.5 µm and indicative results with fungal spores confirmed the penetration through the wooden floor structure. Both measurements showed that the penetration was highly dependent on pressure difference and not dependent on holes in surface boards of the structure. The results are likely to show that surface contacts of mineral wool with other building elements may have an important role on the penetration.

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Section: Discussionmentioning

confidence: 99%

Section: Crawl Space Base Floor Outdoor Air Flow Outdoor Air Flowmentioning

confidence: 98%

Section: Crawl Space Base Floor Outdoor Air Flow Outdoor Air Flowmentioning

confidence: 99%

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Fungal spore transport through a building structure

Airaksinen¹,

Kurnitski²,

Pasanen

et al. 2004

Indoor Air

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“…P j also varies with building ventilation conditions and the geometry of cracks in the building shell. 36,40,41 Although it is known from laboratory studies that complex crack geometry and increased roughness of crack surfaces result in lower P values, the characteristics of cracks in buildings are not well known and are likely to be highly varied within and across buildings. 36,40 Furthermore, size-resolved measurements of P j under a variety of ventilation conditions and building characteristics are limited.…”

Section: Sensitivity Analysesmentioning

confidence: 99%

Variability in the fraction of ambient fine particulate matter found indoors and observed heterogeneity in health effect estimates

Hodas

Meng

Lunden

et al. 2012

J Expo Sci Environ Epidemiol

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Exposure to ambient (outdoor-generated) fine particulate matter (PM 2.5 ) occurs predominantly indoors. The variable efficiency with which ambient PM 2.5 penetrates and persists indoors is a source of exposure error in air pollution epidemiology and could contribute to observed temporal and spatial heterogeneity in health effect estimates. We used a mass balance approach to model F for several scenarios across which heterogeneity in effect estimates has been observed: with geographic location of residence, residential roadway proximity, socioeconomic status, and central air-conditioning use. We found F is higher in close proximity to primary combustion sources (e.g. proximity to traffic) and for lower income homes. F is lower when PM 2.5 is enriched in nitrate and with central air-conditioning use. As a result, exposure error resulting from variability in F will be greatest when these factors have high temporal and/or spatial variability. The circumstances for which F is lower in our calculations correspond to circumstances for which lower effect estimates have been observed in epidemiological studies and higher F values correspond to higher effect estimates. Our results suggest that variability in exposure misclassification resulting from variability in F is a possible contributor to heterogeneity in PM-mediated health effect estimates.

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“…On the other hand, penetration depends on particle dynamics [10]. Particulate matter characteristics generated indoors are strongly connected with the primary indoor sources [11,12], whereas, particles that originate from outdoors are determined by building characteristics, ventilation, transport, particle dynamics and outdoor PM characteristics [10,[13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Modeling of the aerosol infiltration characteristics in a cultural heritage building: The Baroque Library Hall in Prague

Chatoutsidou

Mašková

Ondráčková

et al. 2015

Building and Environment

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Please cite this article as: Chatoutsidou SE, Mašková L, Ondráčková L, Ondráček J, Lazaridis M, Smolík J, Modeling of the aerosol infiltration characteristics in a cultural heritage building: The Baroque Library Hall in Prague, Building and Environment (2015), doi: 10.1016/j.buildenv.2015 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A dynamic mass balance model was introduced taking account particle penetration from outdoors and indoor losses (deposition, ventilation). The model was used to determine deposition rate k and penetration efficiency P in 13 discrete size intervals. Model performance was evaluated using the coefficient of determination (R 2 ) by selecting different pairs of k and P. No unique solution found, thus, averaged values of k and P from the best correlated pairs were used to estimate infiltration factor. Good agreement between infiltration factor and I/O ratio confirmed that modeled k and P were well-estimated. The deposition rate was found to depend strongly on particle size with higher rates for ultrafine and coarse particles. Penetration efficiency, on the other hand, was not clearly related with particle size. The infiltration factor varied substantially with particle size with less effective removal for accumulation fraction (0.1-0.7 µm). Higher infiltration factor for ultrafine particles, compared to coarse particles, indicates that enrichment of the library at this size is caused by penetration from outdoors. On the other hand, human presence during visiting hours found to contribute significantly to coarse particles by increasing the indoor number concentration by a factor of 3, 3.2 and 2 during spring, summer and winter respectively.

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Modeling pollutant penetration across building envelopes

Cited by 234 publications

References 22 publications

Fungal spore transport through a building structure

Fungal spore transport through a building structure

Variability in the fraction of ambient fine particulate matter found indoors and observed heterogeneity in health effect estimates

Modeling of the aerosol infiltration characteristics in a cultural heritage building: The Baroque Library Hall in Prague

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