Assessment of indoor fine aerosol contributions from environmental tobacco smoke and cooking with a portable nephelometer

Bräuer, Michael; Hirtle, Robert; Lang, Barbara; Ott, Wayne R.

doi:10.1038/sj.jea.7500076

Cited by 68 publications

(48 citation statements)

References 15 publications

(20 reference statements)

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“…This differs from our previous finding of no difference between the indoor and outdoor b sp -PM 2.5 regression slopes based on data from the first year of the Seattle study (Liu et al, 2002). In addition to the effect of using an older model neph, this difference in mass scattering efficiencies may also be due to indoorgenerated particles that scatter light more efficiently than the ambient aerosol (Brauer et al, 2000) and/or to the fact that the neph is especially sensitive to the size range in which particles infiltrate most efficiently (B0.1-0.5 mm) (Waggoner and Weiss, 1980;Sarnat et al, 2006). Thus, the particle sizedependence of F inf may alter the size distribution of the ambient aerosol as it comes indoors and result in an indoor aerosol with a slightly increased mass scattering efficiency.…”

Section: Discussioncontrasting

confidence: 98%

Evaluation of the recursive model approach for estimating particulate matter infiltration efficiencies using continuous light scattering data

Allen

Wallace

Larson

et al. 2006

J Expo Sci Environ Epidemiol

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Quantifying particulate matter (PM) infiltration efficiencies (F inf ) in individual homes is an important part of PM exposure assessment because individuals spend the majority of time indoors. While F inf of fine PM has most commonly been estimated using tracer species such as sulfur, here we evaluate an alternative that does not require particle collection, weighing and compositional analysis, and can be applied in situations with indoor sources of sulfur, such as environmental tobacco smoke, gas pilot lights, and humidifier use. This alternative method involves applying a recursive mass balance model (recursive model, RM) to continuous indoor and outdoor concentration measurements (e.g., light scattering data from nephelometers). We show that the RM can reliably estimate F inf , a crucial parameter for determining exposure to particles of outdoor origin. The RM F inf estimates showed good agreement with the conventional filter-based sulfur tracer approach. Our simulation results suggest that the RM F inf estimates are minimally impacted by measurement error. In addition, the average light scattering response per unit mass concentration was greater indoors than outdoors; after correcting for differences in light scattering response the median deviation from sulfur F inf was reduced from 15 to 11%. Thus, we have verified the RM applied to light scattering data. We show that the RM method is unable to provide satisfactory estimates of the individual components of F inf (penetration efficiency, air exchange rate, and deposition rate). However, this approach may allow F inf to be estimated in more residences, including those with indoor sources of sulfur. We show that individual homes vary in their infiltration efficiencies, thereby contributing to exposure misclassification in epidemiological studies that assign exposures using ambient monitoring data. This variation across homes indicates the need for home-specific estimation methods, such as the RM or sulfur tracer, instead of techniques that give average estimates of infiltration across homes.

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Section: Discussioncontrasting

confidence: 98%

Evaluation of the recursive model approach for estimating particulate matter infiltration efficiencies using continuous light scattering data

Allen

Wallace

Larson

et al. 2006

J Expo Sci Environ Epidemiol

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“…(Although our nephelometric data set was purged of samples that were nonsystematically distorted via condensation in the optical chamber, approximate 1-h peak PM concentrations of our study are semiquantitative in that nephelometric response during high-pollution episodes may depart from that derived from 24-h calibration. Published laboratory studies which explore nephelometric response to cooking-generated aerosols suggest that optically determined 1-h peak PM concentrations might overestimate mass by about 10% (Jenkins et al (2004), cooking oil) or underestimate 1-h peaks by a factor of 2.5 (Brauer et al (2000), frying potatoes).…”

Section: Sensitivity Of Measures Of Central Tendency To Censorship Ofmentioning

confidence: 99%

Field performance of a nephelometer in rural kitchens: effects of high humidity excursions and correlations to gravimetric analyses

Fischer¹,

Koshland²

2006

J Expo Sci Environ Epidemiol

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Rural kitchens of solid-fuel burning households constitute the microenvironment responsible for the majority of human exposures to health-damaging air pollutants, particularly respirable particles and carbon monoxide. Portable nephelometers facilitate cheaper, more precise, time-resolved characterization of particles in rural homes than are attainable by gravitational methods alone. However, field performance of nephelometers must contend with aerosols that are highly variable in terms of chemical content, size, and relative humidity. Previous field validations of nephelometer performance in residential settings explore relatively low particle concentrations, with the vast majority of 24-h average gravitational PM 2.5 concentrations falling below 40 mg/m 3 . We investigate relationships between 24-h gravitational particle measurements and nephelometric data logged by the personal DataRAM (pDR) in highly polluted rural Chinese kitchens, where gravitationally determined 24-h average respirable particle concentrations were as high as 700 mg/m 3 . We find that where relative humidity remained below 95%, nephelometric response was strongly linear despite complex mixtures of aerosols and variable ambient conditions. Where 95% relative humidity was exceeded for even a brief duration, nephelometrically determined 24-h mean particle concentrations were nonsystematically distorted relative to gravitational data, and neither concurrent relative humidity measurements nor use of robust statistical measures of central tendency offered means of correction. This nonsystematic distortion is particularly problematic for rural exposure assessment studies, which emphasize upper quantiles of time-resolved particle measurements within 24-h samples. Precise, accurate interpretation of nephelometrically resolved short-term particle concentrations requires calibration based on short-term gravitational sampling.

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“…Higher daytime ratios likely resulted from particles generated indoors and from higher AER during the day as compared with overnight. 4,5,17,18,24,32 Because of their strong association, the independent effects of indoor sources and home ventilation on the ratios could not be examined.…”

Section: Outdoor and Indoor Particle Concentrationsmentioning

confidence: 99%

The Influences of Ambient Particle Composition and Size on Particle Infiltration in Los Angeles, CA, Residences

Sarnat

Coull

Ruíz³

et al. 2006

Journal of the Air & Waste Management Association

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Particle infiltration is a key determinant of the indoor concentrations of ambient particles. Few studies have examined the influence of particle composition on infiltration, particularly in areas with high concentrations of volatile particles, such as ammonium nitrate (NH 4 NO 3 ). A comprehensive indoor monitoring study was conducted in 17 Los Angeles-area homes. As part of this study, indoor/outdoor concentration ratios during overnight (nonindoor source) periods were used to estimate the fraction of ambient particles remaining airborne indoors, or the particle infiltration factor (F INF ), for fine particles (PM 2.5 ), its nonvolatile (i.e., black carbon [BC]) and volatile (i.e., nitrate [NO 3 Ϫ ]) components, and particle sizes ranging between 0.02 and 10 m. F INF was highest for BC (median ϭ 0.84) and lowest for NO 3 Ϫ (median ϭ 0.18). The low F INF for NO 3 Ϫ was likely because of volatilization of NO 3 Ϫ particles once indoors, in addition to depositional losses upon building entry. The F INF for PM 2.5 (median ϭ 0.48) fell between those for BC and NO 3 Ϫ , reflecting the contributions of both particle components to PM 2.5 . F INF varied with particle size, air-exchange rate, and outdoor NO 3 Ϫ concentrations. The F INF for particles between 0.7 and 2 m in size was considerably lower during periods of high as compared with low outdoor NO 3 Ϫ concentrations, suggesting that outdoor NO 3 Ϫ particles were of this size. This study demonstrates that infiltration of PM 2.5 varies by particle component and is lowest for volatile species, such as NH 4 NO 3 . Our results suggest that volatile particle components may influence the ability for outdoor PM concentrations to represent indoor and, thus, personal exposures to particles of ambient origin, because volatilization of these particles causes the composition of PM 2.5 to differ indoors and outdoors. Consequently, particle composition likely influences observed epidemiologic relationships based on outdoor PM concentrations, especially in areas with high concentrations of NH 4 NO 3 and other volatile particles. INTRODUCTIONBecause individuals spend Ͼ85% of their time indoors, 1 accurate assessment of the risks posed by particle exposures is dependent on our ability to characterize indoor concentrations of ambient particles. Key to this characterization is the assessment of particle infiltration indoors. Recent studies conducted under controlled conditions suggest that building design and operation, particle size, and particle composition are important factors influencing infiltration. 2,3 Studies of occupied homes, which allow for better generalization to real-world conditions than experimental studies, also indicate a strong influence of ventilation conditions and particle size on infiltration. 4 -6 However, relatively little data from occupied homes are available to examine the effect of particle composition on infiltration. 7-9 Moreover, these data are limited, lacking repeated sampling within each home, 7,9 particle size measurements, and, in partic...

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Assessment of indoor fine aerosol contributions from environmental tobacco smoke and cooking with a portable nephelometer

Cited by 68 publications

References 15 publications

Evaluation of the recursive model approach for estimating particulate matter infiltration efficiencies using continuous light scattering data

Evaluation of the recursive model approach for estimating particulate matter infiltration efficiencies using continuous light scattering data

Field performance of a nephelometer in rural kitchens: effects of high humidity excursions and correlations to gravimetric analyses

The Influences of Ambient Particle Composition and Size on Particle Infiltration in Los Angeles, CA, Residences

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