Field Evaluation of the Differential TEOM Monitor for Continuous PM<sub>2.5</sub>Mass Concentrations Special Issue of<i>Aerosol Science and Technology</i>on Findings from the Fine Particulate Matter Supersites Program

Jaques, Paul F.; Ambs, Jeffrey L.; Grant, W. Leonard; Sioutas, Constantinos

doi:10.1080/02786820390229435

Cited by 31 publications

(11 citation statements)

References 13 publications

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“…PM 10 mass by MOUDI was approximately 20% lower than that of the dichotomous sampler (possibly due to loss of coarse particles in the MOUDI sampler), but PM 2.5 agreed within 3% of the dichotomous sampler in Pittsburgh. 164 PM 2.5 mass from the dichotomous sampler was approximately 17% lower than MOUDI in Los Angeles, 165 attributed to NO 3 Ϫ volatilization. At a low flow rate (2 L/min), Williams et al 166 showed that a PM 2.5 personal environmental monitor (PEM; MSP, Inc.) used for exposure assessments 167-169 measured 16 -18% higher mass than a collocated FRM.…”

Section: Oc and Ecmentioning

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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Section: Oc and Ecmentioning

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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“…It is well known that volatilization of particulate nitrate and organic compounds occurs during FRM sampling. 1 On the other hand, the TEOM (FDMS) real-time monitor effectively separates and captures both the volatile and nonvolatile aerosol fraction 12 ; thus, the difference between the TEOM (FDMS) and FRM could be explained by the volatilization of semi-volatile species present in the PM at high ambient temperatures. At a higher temperature, ammonium nitrate is easily evaporated into gaseous nitric acid and ammonia; 18 thus, the mass difference between the FRM and TEOM (FDMS) followed the change of the ambient temperature.…”

Section: Continuous Pm 25 Measurements At the Field Sitementioning

confidence: 99%

“…10,11 In addition to having the advantage of real-time monitoring, continuous instruments may have potentially higher accuracy than a discrete filter-based gravimetric method due to a decreased loss of semi-volatile material. 12 For example, the Federal Reference Method (FRM) in Houston, TX and Seattle, WA was observed to underestimate ambient PM mass when compared with continuous methods. 13 The goal of this paper is to provide an evaluation and recommendations associated with the operation of six continuous PM 2.5 monitors under a variety of conditions.…”

Section: Introductionmentioning

confidence: 99%

Evaluation and Comparison of Continuous Fine Particulate Matter Monitors for Measurement of Ambient Aerosols

Zhu

Zhang

Lioy

2007

Journal of the Air & Waste Management Association

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To provide a scientific basis for the selection and use of continuous monitors for exposure and/or health effects studies, and for compliance and episode measurements at strategic locations in the State of New Jersey, we evaluated the performance of seven continuous fine particulate matter (PM 2.5 ) monitors in the present study. Gravimetric samplers, as reference methods, were collocated with realtime instruments in both laboratory and field tests. The results of intercomparison of real-time monitors showed that the two nephelometers used in this study correlated extremely well (r 2 ϳ0.97), and two tapered element oscillating monitors (TEOM 1400 and TEOM filter dynamics measurement system [FDMS]) correlated well (r 2 Ͼ 0.85), whereas two beta gauges displayed a weaker correlation (r 2 Ͻ 0.6). During a summertime controlled (laboratory) evaluation, the measurements made with the gravimetric method correlated well with the 24-hr integrated measurements made with the real-time monitors. The SidePak nephelometer overestimated the particle concentration by a factor of approximately 3.4 compared with the gravimetric method. During a summertime field evaluation, the TEOM FDMS monitor reported approximately 30% higher mass concentration than the Federal Reference Method (FRM); and the difference could be explained by the loss of semi-volatile materials from the FRM sampler. Results also demonstrated that 24-hr average PM 2.5 mass concentrations measured by beta gauges and TEOM (50°C) in winter correlated well with the integrated gravimetric method. Seasonal differences were observed in the performance of the TEOM (50°C) monitor in measuring the particle mass attributed to the higher semi-volatile material loss in the winter weather. In applying the realtime particulate matter monitoring data into Air Quality Index (AQI) reporting, the Conroy method and the 8-hr end-hour average method were both found to be suitable.

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“…A complete discussion of the theory of operation and relevant equations can be found elsewhere. 5,11 The differential TEOM monitor determines the mass concentration both when the ESP is energized and when the ESP is turned off. The reportable net or ambient mass concentration is calculated by subtracting the mass concentration measured during periods while the ESP was energized from the mass concentration measured while the ESP was off.…”

Section: Sesmentioning

confidence: 99%

Laboratory Characterization of Modified Tapered Element Oscillating Microbalance Samplers

Schwab

Hogrefe

Demerjian

et al. 2004

Journal of the Air & Waste Management Association

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Laboratory tests with generated aerosols were conducted to test the efficacy of two recent design modifications to the well-established tapered element oscillating microbalance (TEOM) continuous particulate matter (PM) mass monitor. The two systems tested were the sample equilibration system-equipped TEOM monitor operating at 30°C, which uses a Nafion dryer as part of the sample inlet, and the differential TEOM monitor, which adds a switched electrostatic precipitator and uses a self-referencing algorithm to determine "true PM mass." Test aerosols included ammonium sulfate, ammonium nitrate, sodium chloride, copper (II) sulfate, and mixed aerosols. Aerosols were generated with an atomizer or a vibrating orifice generator and were equilibrated in a 450-L slow flow chamber before being sampled. Relative humidity in the chamber was varied between 10 and 90%, and step changes in humidity were executed while generating aerosol to test the response of the instruments. The sample equilibration system-equipped TEOM monitor does reduce, but not totally eliminate, the sensitivity of the TEOM mass monitor to changes in humidity. The differential TEOM monitor gives every indication of being a very robust technique for the continuous real-time measurement of ambient aerosol mass, even in the presence of semi-volatile particles and condensable gases. INTRODUCTIONThe tapered element oscillating microbalance (TEOM) mass monitor uses a hollow oscillating microbalance to detect and report changes in mass caused by the passage of ambient air through a replaceable filter. 1 The monitor provides a continuous measure of collected mass. The purpose of this work is to understand how to better measure the atmospheric particulate matter (PM) to which people are exposed in the ambient environment. Continuous measurements of PM are desirable for a number of reasons, including (1) the capture of short, but intense, pollution events; (2) hourly mass concentration data are required for use in PM with an aerodynamic diameter less than or equal to 2.5 m (PM 2.5 ) mapping projects; and (3) more highly time resolved data are required for model evaluation. While data with higher time resolution answer some of the objections to the 24-hr integrated filters collected in the U.S. Environmental Protection Agency (EPA) Federal Reference Method (FRM) network, the TEOM monitor still uses a filter for particle collection and is subject to the same artifact and interference problems of other filter-based PM collection methods. These limitations as they relate to the FRM for PM 2.5 2 are discussed and evaluated by Eatough et al. 3 The research described here consists of a thorough laboratory evaluation of modifications to the TEOM monitor. The modifications were made to address the limitations of the basic method and primarily involve treatment of the sample before it reaches the oscillating microbalance. The sample equilibration system (SES)-equipped TEOM monitor 4 was developed to mitigate interferences from water vapor, so extensive laboratory te...

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Field Evaluation of the Differential TEOM Monitor for Continuous PM_2.5Mass Concentrations Special Issue ofAerosol Science and Technologyon Findings from the Fine Particulate Matter Supersites Program

Cited by 31 publications

References 13 publications

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

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

Evaluation and Comparison of Continuous Fine Particulate Matter Monitors for Measurement of Ambient Aerosols

Laboratory Characterization of Modified Tapered Element Oscillating Microbalance Samplers

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Field Evaluation of the Differential TEOM Monitor for Continuous PM2.5Mass Concentrations Special Issue ofAerosol Science and Technologyon Findings from the Fine Particulate Matter Supersites Program

Cited by 31 publications

References 13 publications

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

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

Evaluation and Comparison of Continuous Fine Particulate Matter Monitors for Measurement of Ambient Aerosols

Laboratory Characterization of Modified Tapered Element Oscillating Microbalance Samplers

Contact Info

Product

Resources

About

Field Evaluation of the Differential TEOM Monitor for Continuous PM_2.5Mass Concentrations Special Issue ofAerosol Science and Technologyon Findings from the Fine Particulate Matter Supersites Program