Theoretical model for relating indoor pollutant concentrations to those outside

Shair, F. H.; Heitner, Kenneth

doi:10.1021/es60090a006

Cited by 137 publications

(94 citation statements)

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“…For a given site, at a constant air exchange rate and absent varying indoor sources, the indoor ozone concentration divided by the outdoor ozone concentration (I/O ozone) remains relatively constant (Shair and Heitner, 1974;Hales and Shair, 1974;Weschler et al, 1989Weschler et al, , 1991Weschler et al, , 1992. Table 2 summarizes I/O ozone ratios measured by numerous investigators in a variety of building types.…”

Section: Indoor Ozone Concentrationsmentioning

confidence: 99%

“…The relationship between these sources and The specific sources and sinks that influence indoor ozone concentrations are discussed in the following paragraphs. (Detailed presentation of models that can be used to estimate indoor ozone levels can be found in papers by Shair andHeitner, 1974 andHayes, 1991. ) Outdoor Ozone Concentrations Figure 2 shows outdoor ozone concentrations measured during 1996 at a relatively clean location, Death Valley National Monument, and a relatively polluted location, Burbank, California, USA (California Environmental Protection Agency, 1997).…”

Section: Factors That Influence Indoor Ozone Concentrations Overviewmentioning

confidence: 99%

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Ozone in Indoor Environments: Concentration and Chemistry

Weschler¹

2000

Indoor Air

638

541

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The concentration of indoor ozone depends on a number of factors, including the outdoor ozone concentration, air exchange rates, indoor emission rates, surface removal rates, and reactions between ozone and other chemicals in the air. Outdoor ozone concentrations often display strong diurnal variations, and this adds a dynamic excitation to the transport and chemical mechanisms at play. Hence, indoor ozone concentrations can vary significantly from hour-to-hour, day-to-day, and season-to-season, as well as from room-to-room and structure-to-structure. Under normal conditions, the half-life of ozone indoors is between 7 and 10 min and is determined primarily by surface removal and air exchange. Although reactions between ozone and most other indoor pollutants are thermodynamically favorable, in the majority of cases they are quite slow. Rate constants for reactions of ozone with the more commonly identified indoor pollutants are summarized in this article. They show that only a small fraction of the reactions occur at a rate fast enough to compete with air exchange, assuming typical indoor ozone concentrations. In the case of organic compounds, the ''fast'' reactions involve compounds with unsaturated carboncarbon bonds. Although such compounds typically comprise less than 10% of indoor pollutants, their reactions with ozone have the potential to be quite significant as sources of indoor free radicals and multifunctional (ªCΩO, ªCOOH, ªOH) stable compounds that are often quite odorous. The stable compounds are present as both gas phase and condensed phase species, with the latter contributing to the overall concentration of indoor submicron particles. Indeed, ozone/alkene reactions provide a link between outdoor ozone, outdoor particles and indoor particles. Indoor ozone and the products derived from reactions initiated by indoor ozone are potentially damaging to both human health and materials; more detailed explication of these impacts is an area of active investigation.Key words Ozone; I/O ratio; Indoor chemistry; Aldehydes; Particulates; Free radicals. Practical ImplicationsIndoor ozone contributes to total ozone exposures, and reactions driven by indoor ozone produce submicron particles that contribute to total particulate exposures. Indoor ozone concentrations are highly variable, but can be reasonably esti- Ozone reacts too slowly with most airborne pollutants for the process to be of practical significance. Ozone does react at a faster rate with a small subset of indoor pollutants, but the oxidation products are themselves potentially irritating to humans and damaging to materials.

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Section: Indoor Ozone Concentrationsmentioning

confidence: 99%

Section: Factors That Influence Indoor Ozone Concentrations Overviewmentioning

confidence: 99%

Ozone in Indoor Environments: Concentration and Chemistry

Weschler¹

2000

Indoor Air

638

541

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“…The basic description of a one-compartment mass balance model is given by Shair and Heitner. 12 Ekberg 13,14 has provided an extensive body of experimental evidence for the outcomes of such one-compartment mass balance models. Nazaroff and Cass 15 have extended the mass balance model for multiple compartments and interaction between different compounds.…”

Section: Model Descriptionmentioning

confidence: 99%

“…Mass balance models are employed in exposure assessment 2,9,10 and in finding strategies to reduce indoor pollutant levels. 12,14 In the present study, we considered the one-compartment mass balance model. 12,13 The model compartment is a wellmixed indoor environment in which outside air containing a pollutant penetrates the environment through openings such as windows, doors, and cracks.…”

Section: Model Descriptionmentioning

confidence: 99%

“…12,14 In the present study, we considered the one-compartment mass balance model. 12,13 The model compartment is a wellmixed indoor environment in which outside air containing a pollutant penetrates the environment through openings such as windows, doors, and cracks. If temperature and pressure are assumed to be relative constants in time and space, and the sum of all sink/source terms remains small compared to the mass flowing through the environment, a steady state exists in the mass balance of air.…”

Section: Model Descriptionmentioning

confidence: 99%

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Modeling Relationships between Indoor and Outdoor Air Quality

Freijer

Bloemen

2000

Journal of the Air & Waste Management Association

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Information about the ratio between indoor and outdoor concentrations (IO ratios) of air pollutants is a crucial component in human exposure assessment. The present study examines the relationship between indoor and outdoor concentrations as influenced by the combined effect of time patterns in outdoor concentrations, ventilation rate, and indoor emissions. Two different mathematical approaches are used to evaluate IO ratios. The first approach involves a dynamic mass balance model that calculates distributions of transient IO ratios. The second approach assumes a linear relationship between indoor and outdoor concentrations. We use ozone and benzene as examples in various modeling exercises. The modeled IO ratio distributions are compared with the results obtained from linear fits through plots of indoor versus outdoor concentrations.

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1999

Estimating the Flammable Mass of a Vapor Cloud

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Theoretical model for relating indoor pollutant concentrations to those outside

Cited by 137 publications

References 5 publications

Ozone in Indoor Environments: Concentration and Chemistry

Ozone in Indoor Environments: Concentration and Chemistry

Modeling Relationships between Indoor and Outdoor Air Quality

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