I. Introduction II. Model Development III. Summary of Model Input Parameters IV. Selected Model Results V. Single-Source and Regional Results VI. Concl usions and Recommenaa tions Acknowledgments Appendix A: Detailed Description of Model Input Parameters Appendix B: Nine-house Study Appendix C: Selected Graphic Output of Preliminary Model Predictions PREFACEThis report is the first in a series intended to assess residential air-pollution concentrations in the U.S. housing stock. A "macromodel" has been developed to simulate/predict selected residential air-pollution concentration distributions across specified house populations.Combustion pollutants are initially addressed because (1) they are a major class of indoor pollutants with documented adverse health effects at elevated concentrations,the underlying mathematical relationships are somewhat understood, and (3) sufficient input data exist to allow the macromodel to obtain results (i~e.,predictions). This report addresses the macromodel development and preliminary predictions for carbon monoxide, nitrogen dioxide, and respirable suspended particles. Subsequent reports address (1) sensitivity analysis of the macromodel, (2) micro/macro comparisons, and (3) preliminary predictions for organic compounds and sulphur dioxide.i ABSTRACT A simulation model (also call a "macromodel") has been developed to predict residential air pollutant concentration distributions for specified populations. The model inputs include the market penetration of pollution sources, pollution source characteristics (e.g., emission rates, source usage rates), building characteristics (e.g., house volume, air exchange rates), and meteorological parameters (e.g., outside temperature). Four geographically distinct regions of the U.S. have been modeled using Monte Carlo and deterministic simulation techniques. Single-source simulations were also conducted. The highest predicted CO and N02 residential concentrations were associated with the winter-time use of unvented gas and kerosene space heaters. The highest predicted respirable suspended particulate concentrations were associated with indoor cigarette smoking and the winter-time use of non-airtight wood stoves, radiant kerosene heaters, convective unvented gas space heaters, and oil forced-air furnaces. Future field studies in this area should (1) fill information gaps identified in this report, and (2) collect information on the macromodel input parameters to properly interpret the results. It is almost more important to measure the parameters that affect indoor concentration than it is to measure the concentrations themselves. ii I -2Approaches to assess total exposures to air pollutants fall into three categories: (1) personal monitoring (i.e., dosimetry); (2) monitoring of concentrations in the various human environments; and (3) modeling of exposures based on a wide array of information, including pollutant sources, building characteristics, pollutant behavior, and human activities. These approaches can be complementary. Moreover, the ...

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Operation of an unvented combustion appliance indoors can elevate pollutant levels. We have determined the emission rates and source strengths of a variety of pollutants emitted from eightunvented gasfired space heaters operated with well adjusted air shutters at partial and full input in a 27-m 3 chamber under a range of ventilation conditions. Emission rates were also determined for some heaters with poorly adjusted air shutters. In addition to monitoring carbon monoxide, carbon dioxide,nitric oxide, nitrogen dioxide, formaldehyde, and respirable suspended particles, we also determined oxygen consumption rates.Results indicate that the emissions of nitrogen dioxide and carbon dioxide from all heaters were high enough to be of concern, both in singleroom environments and, based upon calculation, in residential-sized buildings. Depending upon the particular heater and its specific air shutter adjustment, carbon monoxide and, to a lesser extent, formaldehyde emissions can be high enough to cause concern.The emission rates from this study can be used along with information about building characteristics to calculate pollutant levels in a wide variety of indoor environments.

In rare instances, carbon monoxide (CO) levels in houses can reach dangerously high concentrations, causing adverse health effects ranging from mild headaches to, under extreme conditions, death. Hundreds of fatal accidental carbon monoxide poisonings occur each year primarily due to the indoor operation of motor vehicles, the indoor use of charcoal for cooking, the operation of malfunctioning vented and unvented combustion appliances, and the misuse of combustion appliances. Because there is a lack of simple, inexpensive, and accurate field , sampling instrumentation, it is difficult for gas utilities and researchers to co_nduct field r~search studies designed . to quantify the concentrations of CO in residences.Determining the concentration of CO in residences is the first step towards identifying the high risk appliances and high-CO environments which pose health risks.