Air exchange rates

The concentration of indoor pollutants is a function of removal processes such as dilution, filtration, and destruction. Dilution is a function of the air exchange rate and the ambient air quality. Gases and particulate matter may also be removed from indoor air by deposition on surfaces. Filtration systems are part of many ventilahon systems. As air is circulated by the air-conditioning system it passes through a filter which can remove some of the particulate matter. The removal efficiency depends on particle size. In addition, some reactive gases like NOj and SOj are readily adsorbed on interior surfaces of a building or home. 

Data files on the THERdbASE CD are 1990 Bureau of Census Population Information, California Adult Activity Pattern Study (1987-88), AT T-sponsored National Activity Pattern Study (1985), Chemical Agents from Sources, Chemical Agent Properties, Air Exchange Rates, Information from EPA s TEAM (Total Exposure Assessment Methodology) Studies, Information from EPA s NOPES (NonOccupational Pesticides Exposure Study) Studies, Information from EPA s AIRS (Aerometric Information Retrieval System), and Human Physiological Parameters. 

Zhivov, A. M. and Kclina, E. L. 1989. Evaluation of air exchange rate with air supply with inclined jets. In Occupational Safety Technique and Industrial Sanitary Collected Papers of the Occupational Safety Institutes under AUCCTU, Mosciow. Profizdat, pp. 33-38,... 

The air exchange rate, G , required for temperature control in the occupied zone can be calculated from the room heat balance equation ... 

Charleswofth, P. S. 1988. Air Exchange Rate and Airtightness Measurement Techniques An Applications Guide. Air Infiltration and Ventilation Center, Coventry, UK. 

The relationships between air exchange rate and temperature difference were determined using COMB (Fig. 11.51) and then integrated as the ventilation model in the thermal model. The rhermai behavior is modeled with the TRNSYS multizone type, considering the hall and the room below the thick concrete test floor slab. For the hall, a room model with two air temperature nodes (one for the occupied zone and one for the rest of the hall) and geometrically detailed radiation exchange is used. 

Nazaroff, W. W., F. J. Offermann and A. W. Robb, Automated System for Measuring Air-Exchange Rate and Radon Concentration in Houses,... 

The different air exchange rates in a room were obtained by closed, and partly opened windows. 

I. As discussed in this chapter, a relatively new area in indoor air pollution is that of hydroxyl radical chemistry. However, the importance of indoor OH chemistry (as well as 03 and N03 chemistry) is determined by the rates of the reactions compared to the rate of air exchange. An OH concentration of 7 X 105 cm-3 has been reported in an indoor air environment by Weschler and Shields (1997a). Assess the importance of the OH reaction for the removal of limonene indoors compared to its removal by reaction with 03. The 03-limonene rate constant is 2 X 1CT16 and the OH-limonene rate constant is 1.7 X 10-l() cm3 molecule-1 s-1. Take the 03 concentration to be 20 ppb. How do these compare with a typical air exchange rate of 0.75 h-1 used in these experiments ... 

Typically, either airflow velocity or air flow volume testing will be performed. Total volume may in turn be used to determine the air exchange rate (room air volume changes per hour) for the clean room. 

Indoor air quality has been a public health concern for several decades now. Indoor air quality is affected both by infiltration of outdoor air in buildings and indoor sources such as smoking, gas cooking, and use of consumer products [6]. Penetration of particles into indoor environments depends on particle size, air exchange rates, and other factors. Consideration of indoor sources is important because they may be associated with significant health effects, e.g., environmental tobacco smoke. Presence of indoor sources may further complicate assessment of the impact of outdoor air on indoor air. In this chapter we separately describe the impact of indoor sources and outdoor air on indoor pollution, because health effects of outdoor and indoor generated particles may differ as their composition differs [7]. 

P = penetration efficiency (dimensionless) a = air exchange rate (h ) k = decay rate indoors (h 1)... 

The real-time monitoring of some species concentration distribution in indoor air is an effective way to evaluate the dispersion of fresh air and/or gas-phase chemical pollutants, for example when determining the ventilation effectiveness, the air exchange rate (ACH) or the air age distribution for a given space (Park et al., 1998 Shin et al., 2005). It also provides a helpful validation for transient... 

Park, J.H., Spengler, J.D., Yoon, D.W. et al. (1998) Measurement of air exchange rate of stationary vehicles and estimation of in-vehide exposure. Journal of Exposure Analysis and Environmental Epidemiology, 8 (1), 65-78. 

In the simplest case a compound is emitted from a sample into the chamber and removed with exhaust air. This so-called dilution-model has been introduced by Dunn and Tichenor (1988) for a source with constant and exponentially decaying emission rate, respectively. A more sophisticated model requires the compartments source, chamber, exhaust and sink. The rate constants k, describe the exchange of mass between dilFerent sections. The parameter fc2 represents the air exchange rate n. Figure 5.5 shows a scheme of the two-sink model after De Bortoli et al. (1996) as an extension of the full-model ansatz after Dunn and Tichenor (1988) with fci 5 Z 0 und ks = 0. Equations 5.5 and 5.6 are solutions of the simple dilution-model with k3 s = 0 for constant emission and exponentially decaying emission, respectively. 

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