Indoor Pollutants (1981) / Chapter Skim
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VI. Monitoring and Modeling of Indoor Air Pollution
VI. Monitoring and Modeling of Indoor Air Pollution
Pages 259-301
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From page 259... ...
Several problems emerge with such modif ications, and those problems are discussed here, as well as instruments designed specif ically for the sampling of indoor air. Personal monitors are increasingly recognized as powerful scientific tools for determining individual and population exposure to a it pollutants .
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From page 260... ...
Thus, a n',mher of special problems arise: the quality of indoor air is affected by a broad spectrum of pollutants from both outdoor and indoor sources; measurements of indoor air concentrations may require sampling instruments considerably different from those used in the outdoor or industrial environment; and the air volume inside a building is finite, and the rate of air exchange (especially in residential units) may be very low, and therefore, when air samples are drawn from an occupied space by external samplers, the s~mplinq flow rate must be so low a.
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From page 261... ...
pollutants by the EPA -- carbon monoxide, sulfur dioxide, nitrogen dioxide, ozone, and total nonmethane hydrocarbon.
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From page 262... ...
and then measuring total alpha acezvley on one filter with an alpha-decay ratemeter. Integrated sampling techniques have several advantages: they are less expensive and require lest manpower than continuous monitors, they can be used to measure concentrations that are too low to be measured directly, samples can often be analyzed later at a more convenient time or place, and average concentrations over long periods are easily obtained.
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From page 263... ...
'' Grab sampling has been used to estimate concentrations of radon, tracer gases, and organic compounds. Grab sampling can be used to measure radon concentrations by pumping a known volume of air through a filter into a Tedlar24 bag, which is impervious to radon.
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From page 264... ...
In a similar method, the equilibrium-ooncentration method, ~ tracer gas is released at a constant rate into the building space. .' In the s~eady-steee condition with perfect mixing, the indoor concentration will reach a steady-atate value.
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From page 265... ...
PERSONAL MONITORS Over the last 2 decades, a wide variety of miniaturized air samplers have become available that collect gaseous and particulate samples from the immediate vicinity of people, even as they conduct their normal activities. The initial devices used battery-powered samplers, defined as ~nonpassive..
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From page 266... ...
An EPA feasibility study38 identified useful methods for monitoring sulfur dioxide, nitrogen dioxide, and ozone. Another EPA symposiums' explored the use of available technology for health~ef fects studies and other uses .
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From page 267... ...
The size of the sampler can be varied, but attention must be given to scaling factors. ~ ~ ' ° Diffusion samplers have reportedly been used for water vapor and sulfur dioxide," nitric oxide,' t Is aniline,~3 benzene, 4 Is ammonia,'2 carbon monoxide, and NQx ' s An activated-carbon element has been used as the collector in a badge that has an open grid to define the geometry of the gaseous diffusion port.
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From page 268... ...
'these techniques have been reviewed in detail by Linch55 and Saltz~n.~ A recent development in personal monitors involves ~ pump that ispositioned next to the wearer's diaphragm by a light harness. The volume of air pumped by the motion of the thoracic cavity is recorded by an electronic package, which may be checked by ~ detached readout system.
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From page 269... ...
As previously indicated, there can be substantial variations between area level measurements and personal exposure measurements. By monitoring exposure of individuals with individual air pollution monitors in areas also monitored with fixed stations, one would obtain the distribution of individual exposures in relation to measurement.
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From page 270... ...
nitrogen dioxide and sulfur dioxide were
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From page 271... ...
271 35 30 25 20 Q g O 15 5 i _ l 1~- ~ . ~ I I ' t I I 1 ~ Carbon Monoxide Concentrstions in Vehicle A Arnb~nt CO Concentrations in City I ~ / \~ During Commuting Hours ~ I I 1 1 1 1 1 8 101214 16 18 20 22 4 6 8 1012 14 16 JULY AUGUST FIGURE VI-l Carbon monoxide concentrations in vehicle, compared withl~:bient concentrations in city.
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From page 272... ...
Exposure to nitrogen dioxide tended to be greeter in children exposed to smoking at home, but the dif ferences were not statistically signif icant. AS with sulfur dioxide, seean personal exposure values {61.3 ~ 7.2 ug/~3)
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From page 273... ...
273 Electric S - 50 FIXED ~ 30 At O 10 lo 70 at o ~ sa tar at z 30 o c' o z 10 PER=HAL F B 1 B: l ( ' I 1 2 3 WEEK t _~ _ 1 1 ~ ~ I I 3 4 1 2 3 4 WEEK G" Sto'.
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From page 274... ...
There were at least three complete sample days for each person. Mean personal exposures to respirable particles and sulfates for each city were determined on the basis of mean outdoor concentrations.
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From page 275... ...
5 36 18. O Tot al Weightet-average weekly exposure: 1.1 1lg/m3 aData from Fuga8 et al.
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From page 276... ...
m ey noted that the use of fixed-station measurements to define population exposure may not reflect worat-exposure situations, indoor exposures to carbon monoxide fray cigarette smoke, or exposures from faulty heating systems.
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From page 277... ...
First, it provides a framework for interpreting experimental results and for planning new experiments. Specifically, a model is useful in relating indoor pollutant concentrations to various geometric, ventilation, source, and sink parameters.
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From page 278... ...
Experimental techniques for obtaining net exchange rates between indoor and outdoor air have been reviewed by Georgii3' and Gilath.~i The use of sulfur hexafluoride, SF6, as ~ tracer for air-exchange-~ate studies appear" to be increasingS air maples can be collected by hand in the region of interest, 22 remotely, .. or with author ted instruments.
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From page 279... ...
were needed to obtain a satisfactory description. Sulfur hexafluoride tracer experiments.
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From page 280... ...
280 values of the perimeters should be resist", if the Mel is to be of broad value. The aid of any model should be to explain {and predict} ss many data as possible with the Tallest possible number of ad j ustable parameters .
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From page 281... ...
Sulfur hexafluoride tracer experiments have shown that reentry of a portion of the fume-hood exhaust is usually the dominant factor in determining the concentrations of the pollutants to which all persons are exposed in the laboratory building. Indoor concentrations of fume-hood exhausts, normalized to the source ~ =~ _— —~ —~~~e ~~e— (8)
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From page 282... ...
Milly'5 used a single-compar~nt model involving the instantaneous introduction of a nonreactive contaminant with a pollutant-free input air stream in his discussion of chemical attack of tanks and fortifications. Caller used a single-compartment model in his analysis of the protection afforded by building against biologic~warfare aerosol attack, he permitted the outside concentration to vary with time and took into account the surface removal of aerosol by Beans of ~ firet~order sink term' his results can also be used to describe doses associated with radioactive or chemical contaminants.
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From page 283... ...
Moschandreas (personal communication ~ used a single-compartment model of air pollution in nonworkplace indoor environments in Baltimore, Washington , D.C., Pittsburgh , Chicago, and Denver . He monitored carbon monoxide, nitric oxide, nitrogen dioxide, sulfur dioxide, ozone, · methane, total hydrocarbons, and carbon dioxide continuously for per iods of approximately 14 d in each of f ive detached dwellings {townhouses}, six apartment units, two mobile homes, and one school.
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From page 284... ...
OOR CONCENTRATION OF OZOIME-WITHIN Ist, 2nd ond 3rd FLOORS OF SPALDiNG LABORATORY t ~ x' ~ ~ TlV fOR 0~ I ~ '4` ~ \ my' ~ / ~_~\t -A ~ i Too _ ~~ - J ~ _ 1- i~SYSTEl~ I off I luX.S1StE~ ox 1:34} 2:00 2:30 3:00 3:30 PM TIME (PD.T.) Figure VI-3 Relative indoor and outdoor ozone concentrations.
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From page 285... ...
SUNDRY AND CONCLUSIONS The main purpose of an indoor air quality model is to show the relationships of indoor pollutant concentrations to those outside, to geometric and ventilation characteristics of a structure, and to internal sources and sinks. When the characteristic time for mixing throughout the region of interest is short, compared with the characteristic residence time, the region can be considered as a well-mixed ~compartment..
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From page 286... ...
Fugas27 made one of the first attempts to compute total exposure from experimental data; her approach we" intended only as an illustrative example. She obtained measurements of average concentrations of lead, manganese, and sulfur dioxide during the winter of 1972-1973 from official Monitoring stations in the city.
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From page 287... ...
are expressed in Pg/m3, and values for Ct (integrated exposure) are expressed in ug-h/m .
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From page 288... ...
Because of the importance of considering the mobility patterns of population subgroups, Mbschandress and Morsel examined U.S. census data to define the percentage of each of six subgroups in the total population: housewives, office personnel, industrial workers, outdoor workers, elderly and infirm people, and students.
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From page 289... ...
Ideally, there would be an effective technique for determining the entire frequency distribution of exposures of the population to air pollution. As discussed above, two approaches are used for estimating the frequency distribution of human air-pollution exposures: modeling, which relates the activities of persons as a function of time and the concentrations to which they are exposed; and field studies, which use personal monitors to cover a large enough population sample (or a stratified sample)
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From page 290... ...
290 8 _ _ ._ C _ "D O o-O Me, ~ 0—~5 ~ _ =0 c0 c0 4_ ~ ~ ~ ~ ~ NlYiiNlllYij~ L.~ -- ~\ , ~ ~x ~ ~ · · I I I · · I _ is a o _ qdd uol4~'u.:Uoo~4 a; o 0 0 o ," V V ~ 3 C)
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From page 291... ...
Proceedings of the Symposium on the Development and Usage of Personal Monitors for Exposure and Health Effect Studies .
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From page 292... ...
~ ~ MY W.' i i \\\ ! n , \ \ ~ Hi\ ~.~ \\ hi\ , 1.~ FIGURE VI-5 Graphic representation of person-environment-time Stray in computer simulation model of exposure to air pollution suggested by Ott.
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From page 293... ...
Proceedings of the Symposium on the Development and Usage of Personal Monitors for Exposure and Health Effect Studies.
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From page 294... ...
Proceedings of the Symposium on the Development and Usage of Personal Monitors for Exposure and Health Effect Studies.
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From page 295... ...
Wallace, Eds. Proceedings of the Symposium on the Development and Usage of Personal Monitors for Exposure and Health Effect Studies.
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From page 296... ...
Air. Lawrence Berkeley Laboratory Report I,BL-1.
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From page 297... ...
Proceedings of the Symposium on the Development and Usage of Personal Monitors for Exposure and Health Effect Studies, January 22-24, 1979, Chapel Hill, N.C.
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From page 298... ...
R A Field Quality Assurance Evaluation of Two Personal Monitors for Carbon Monoxide.
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From page 299... ...
Proceedings of the Symposium on the Development and Usage of Personal Monitors for Exposure and Health Effect Studies.
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From page 300... ...
Proceedings of the Symposium on the Development and Usage of Personal Monitors for Exposure and Bealth Effect Studies.
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From page 301... ...
Proceeding. of the Symposium on the Development and Deage of Personal Monitors for Exposure and Health Effect Studies.
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