Residential inter-zonal ventilation rates for exposure modeling

Abstract

Residential inter-zonal (e.g., between rooms) ventilation is comprised of fresh air infiltration in and exfiltration out of the whole house plus the "fresh" air that is entering (and exiting) the room of interest from other rooms or areas within the house. Clearly, the inter-zone ventilation rate in any room of interest will be greater than the infiltration/exfiltration ventilation rate of outdoor air for the whole house. The purpose of this study is to determine how much greater the inter-zonal ventilation rate is in typical U.S. residences compared to the whole house ventilation rate from outdoor air. The data for this statistical analysis came from HouseDB, a 1995 EPA database of residential ventilation rates. Analytical results indicate that a lognormal distribution provides the best fit to the data. Lognormal probability distribution functions (PDFs) are provided for various inter-zonal ventilation rates for comparison to the PDF for the whole house ventilation rates. All ventilation rates are expressed as air change rates per hour (ACH). These PDFs can be used as inputs to exposure models. This analysis suggests that if one were performing a deterministic analysis for unknown housing stocks in the U.S., a default mean and median ACH values of 0.4/hr and 0.3/hr, respectively, for whole house ventilation would be appropriate; and 0.7/hr and 0.6/hr, respectively, for inter-zonal ventilation.

Assessing Human Exposure to SVOCs in Materials, Products, and Articles: A Modular Mechanistic Framework

“…In addition to chemical-related model parameters, those describing specific exposure scenarios may also be unknown or highly uncertain. Whenever possible, variability has to be taken into account with respect to exposed populations and occupant characteristics, 123 occupant behaviors, 8,124 and indoor environmental settings 125,126 . Applying Monte Carlo-based approaches to include parameter distributions and addressing certain "special case" scenarios to identify particularly sensitive populations should be part of the application of the framework.…”

“…In addition to chemical-related model parameters, those parameters describing specific exposure scenarios may also be unknown or highly uncertain. Whenever possible, variability has to be taken into account with respect to exposed populations and occupant characteristics, , occupant behaviors, ,,, and indoor environmental settings. , Applying Monte Carlo-based approaches to include parameter distributions and addressing certain activities to identify high exposure situations should be part of the application of the framework. It has been shown that cooking and cleaning activities greatly enhance the levels of SVOCs in indoor environments compared to background levels. ,, The possibility of aggregate exposures due to certain occupant behaviors and potential consequences for exposed individuals should thus be incorporated in the exposure assessment .…”

“…Whenever possible, variability has to be taken into account with respect to exposed populations and occupant characteristics, 204,205 occupant behaviors, 9,64,146,206 and indoor environmental settings. 207,208 Applying Monte Carlo-based approaches to include parameter distributions and addressing certain activities to identify high exposure situations should be part of the application of the framework. It has been shown that cooking and cleaning activities greatly enhance the levels of SVOCs in indoor environments compared to background levels.…”

From the Editor: JOEH supplemental materials

“…In other cases, a sufficiently dense methodological description might detract from the main objective of a manuscript, and putting procedures [1][2][3] or supporting equations [4] in the supplemental materials makes the manuscript easier to read while providing supporting evidence of the scientific merit of the study to readers. Furthermore, customized software, [5] computer or spreadsheet coding, [6] or data processing techniques [7] used to generate or analyze data may need to be explained in more detail than is reasonable within the body of the manuscript.…”