How good is the well-mixed assumption for particulate matter exposure?

Research output: Chapters, Conference Papers, Creative and Literary WorksRGC 12 - Chapter in an edited book (Author)peer-review

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Author(s)

Detail(s)

Original languageEnglish
Title of host publicationIndoor Work and Living Environments
Subtitle of host publicationHealth, Safety and Performance
EditorsRobert G. Harris, Daniel P. Moore
PublisherNova Science Publishers, Inc.
Pages195-221
ISBN (print)9781617285219, 9781607413752
Publication statusPublished - 2009

Abstract

Assessments of human exposure to indoor air contaminants usually adopt wellmixed models. However, daily observations and experiences have shown various degrees of imhomogeneity and spatial variation of contaminant concentrations in indoor environments. Due to the large diffusion coefficients, gases pollutants can be assumed as passive contaminants which mean that they can move in the same manner as the airflow under the influences of advection, diffusion and turbulence. Under such circumstances, contaminants will be mixed rapidly and uniform mixing can be achieved fairly easily. Unlike gases pollutants, particulate matter usually cannot be assumed as passive contaminants, due to some inherent physical properties of particles. Particle mass and deposition are among the most important characteristics that distinguish particles from gases and both of the two effects become increasingly important as particle size increases. There are various factors influencing the ultimate particle distribution and deposition of indoor particles. Size of particles (fine vs. coarse), ventilation schemes (conventional type vs. displacement), source-to-receiver orientation and distance (close vs. far) and types of pollutant emission (episodic vs. continuous) all have various degrees of impacts on the particle distribution in indoor environments. Although the limitation of the well-mixed model is well known, there has been little research reported in the published literature to quantify the accuracy arising from such assumption on human exposure assessment. In some scenarios, well-mixed assumption is a good approximation while large derivation could be resulted in some cases.

Citation Format(s)

How good is the well-mixed assumption for particulate matter exposure? / Lai, Alvin C. K.; Wu, C. L.
Indoor Work and Living Environments: Health, Safety and Performance. ed. / Robert G. Harris; Daniel P. Moore. Nova Science Publishers, Inc., 2009. p. 195-221.

Research output: Chapters, Conference Papers, Creative and Literary WorksRGC 12 - Chapter in an edited book (Author)peer-review