Intercomparison of ambient aerosol samplers used in western visibility and air quality studies

Mathai, C.V.; Watson, John G.; Rogers, C. F.; Chow, Judith C.; Tombach, Ivar; Zwicker, Judith O.; Cahill, Thomas M.; Feeney, Patrick; Eldred, Robert A.

doi:10.1021/es00077a021

Cited by 22 publications

(11 citation statements)

References 3 publications

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“…During the sampling period, the Odean station had 35% higher PM 10 levels than the Chulalongkorn station ( the 24-h averages: 105 g/m 3 for Odean and 77 g/m 3 for Chulalongkorn). Overall, among the three collocated ambient stationary monitor types, there were significant but low correlations compared with other reported studies where r ranged from 0.89 to 0.99 ( Jaklevic et al, 1981;Elzakker and Dermeulen, 1989;Mathai et al, 1990 ) . The ambient samplers are designed for continuous operation over a long period of time with stable performance.…”

Section: Tsai Et Alcontrasting

confidence: 53%

Indoor/outdoor PM10 and PM2.5 in Bangkok, Thailand

Tsai

Smith

Vichit-Vadakan

et al. 2000

J Expo Sci Environ Epidemiol

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Twenty -four -hour averaged PM 10 and PM 2.5 concentrations were obtained by using 4 -liter -per -minute -pumps and impactors in microenvironments of a busy shopping district and a university hospital campus. In both areas, most people live directly adjacent to their worksites Ð minimizing the need to measure commuting exposure as part of total daily exposure. Co -located samplers were set in indoor microenvironments, the near -ambient zone of the households, and at nearby streetside central ambient monitoring stations. Smoking and use of other indoor PM sources were recorded daily via questionnaires. Consistent with previous studies, smoking and the use of charcoal stoves increased indoor particulate matter levels. The sampled air -conditioned hospital area had substantially lower particle concentrations than outdoors. A simple total exposure model was used to estimate the human exposure. The averaged ratios of co -located PM 2.5 / PM 10 concentrations in various microenvironments are reported for each location. A single daily indoor average PM 10 concentration for all households measured in a given sampling day is calculated for correlation analysis. Results showed that day -to -day fluctuations of these calculated indoor PM 10 levels correlated well with near -ambient data and moderately well with ambient data collected at the nearby central monitoring site. This implies that ambient monitors are able to capture the daily variations of indoor PM levels or even personal exposure and may help explain the robust association of ambient PM levels and health effects found in many epidemiological studies. Absolute PM exposures, however, were substantially underestimated by ambient monitors in the shopping district, probably because of strong local sources. Journal of Exposure Analysis and Environmental Epidemiology (2000) 10, 15 ± 26.

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Section: Tsai Et Alcontrasting

confidence: 53%

Indoor/outdoor PM10 and PM2.5 in Bangkok, Thailand

Tsai

Smith

Vichit-Vadakan

et al. 2000

J Expo Sci Environ Epidemiol

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“…Methods are comparable when slope equals unity and the intercept equals zero within three standard errors, r is Ͼ0.90 (or R 2 Ͼ 0.81), and average ratios equal unity within one standard deviation; predictable if r Ͼ 0.90, but slope and intercept fail the requirements for comparability; and not related if r Ͻ 0.90. 202,313 Most studies use correlation and linear regression of collocated measurements. Watson and Chow 202 and Park et al 265 evaluated equivalence, comparability, and predictability on the basis of the above criteria to maintain consistency with EPA.…”

Section: Data Analysis Techniques and Definitionsmentioning

confidence: 99%

Advances in Integrated and Continuous Measurements for Particle Mass and Chemical Composition

Chow

Doraiswamy

Watson

et al. 2008

Journal of the Air & Waste Management Association

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Recent improvements in integrated and continuous PM 2.5 mass and chemical measurements from the Supersite program and related studies in the past decade are summarized. Analytical capabilities of the measurement methods, including accuracy, precision, interferences, minimum detectable levels, comparability, and data completeness are documented. Upstream denuders followed by filter packs in integrated samplers allow an estimation of sampling artifacts. Efforts are needed to: (1) address positive and negative artifacts for organic carbon (OC), and (2) develop carbon standards to better separate organic versus elemental carbon (EC) under different temperature settings and analysis atmospheres. Advances in thermal desorption followed by gas chromatography/ mass spectrometry (GC/MS) provide organic speciation of approximately 130 nonpolar compounds (e.g., n-alkanes, alkenes, hopanes, steranes, and polycyclic aromatic hydrocarbons [PAHs]) using small portions of filters from existing integrated samples. Speciation of water-soluble OC (WSOC) using ion chromatography (IC)-based instruments can replace labor-intensive solvent extraction for many compounds used as source markers. Thermal gasbased continuous nitrate and sulfate measurements underestimate filter ions by 10 -50% and require calibration against on-site filter-based measurements. IC-based instruments provide multiple ions and report comparable (Ϯ10%) results to filter-based measurements. Maintaining a greater than 80% data capture rate in continuous instruments is labor intensive and requires experienced operators. Several instruments quantify black carbon (BC) by optical or photoacoustic methods, or EC by thermal methods. A few instruments provide real-time OC, EC, and organic speciation. BC and EC concentrations from continuous instruments are highly correlated but the concentrations differ by a factor of two or more. Site-and season-specific mass absorption efficiencies are needed to convert light absorption to BC. Particle mass spectrometers, although semiquantitative, provide much information on particle size and composition related to formation, growth, and characteristics over short averaging times. Efforts are made to quantify mass by collocating with other particle sizing instruments. Common parameters should be identified and consistent approaches are needed to establish comparability among measurements.

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“…Mathai et al 958 recognized that showing differences between measurement methods is not a useful goal of intercomparison studies; the studies must be designed to determine why such differences exist. This can only be done when all inlets and filter media are well-characterized, when inlets are maintained, when volumetric and laboratory measurements are all traceable to the same standards, when pump exhausts are prevented from contaminating the sampled air, when concentration variations across the sampler array are characterized with monitors of similar design, and when periodic performance tests are conducted to estimate measurement precision.…”

mentioning

confidence: 99%

Measurement Methods to Determine Compliance with Ambient Air Quality Standards for Suspended Particles

Chow

1995

Journal of the Air & Waste Management Association

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656

426

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One of the most important parts of formulating a National Ambient Air Quality Standard is specifying the measurement methods for determining and attaining compliance. The samples taken for compliance are often pushed beyond their original purpose to identify sources, to evaluate the effectiveness of controls, and to determine relationships between pollution levels and public health. A full understanding of available sampling and analysis methods is needed, as well as an analysis of their costs, before acceptable monitoring approached can be specified. This review identifies issues related to measurement methods used to determine compliance with standards, describes current and future measurement methods and their limitations, and determines the extent to which existing technology can meet shortterm and long-term needs for measuring compliance.

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Intercomparison of ambient aerosol samplers used in western visibility and air quality studies

Cited by 22 publications

References 3 publications

Indoor/outdoor PM10 and PM2.5 in Bangkok, Thailand

Indoor/outdoor PM10 and PM2.5 in Bangkok, Thailand

Advances in Integrated and Continuous Measurements for Particle Mass and Chemical Composition

Measurement Methods to Determine Compliance with Ambient Air Quality Standards for Suspended Particles

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