NARSTO Measurement Methods Compendium

Particulate Matter Methods
  1. Particulate Matter - size less than or equal to 10 micrometers (PM10)

    1. Gravimetric Methods - exchangeable filters (FRM)
      1. Basis: An air pump draws ambient air at a constant flow rate into a specially shaped inlet where particulate matter is separated into size fractions. Particulate matter is then collected on a filter. Each filter is weighed before and after use, to determine the net mass gain due to collected matter. The total volume of air filtered is known from the constant air flow, and the difference in filter weights is used to calculate the particulate matter concentration in micrograms per cubic meter (µg/m3) of air.
      2. Range: The concentration range is 30 to 300 µg/m3 for test conditions. (Ref. 24, Para. 53.34, Table C-4)
      3. Lower detection limit, or lower quantifiable limit: This limit is not set but is permitted to vary according to filter technology. (Ref. 25, Para. 3.1)
      4. Temperature tolerance: Samplers must operate over a -30° to +45°C temperature range (Ref. 28, Para. 7.4.7). Some devices are offered with temperature protection features, which are optional.
      5. Known Interference:
        1. Particulate matter may be lost during filter handling and weighing procedures, especially if filter is exposed to warming.
        2. Gaseous species may contaminate filters.
        3. Humidity and absorbed water may be difficult to control both during operations and when handling filters.
        4. Removing filters and transporting to a lab for analysis may affect results.
        5. Meteorological conditions may affect flow rate.
      6. Notes of Interest:
        1. Precision (means agreement among successive measures of equal samples) is defined by EPA as follows: must be 5 µg/m3 for PM10 concentrations below 80 µg/m3 and 7 percent for PM10 concentrations above 80 µg/m3 (Ref. 25, Para. 4.1), but the wording probably means "at least 5 µg/m3." This requirement is simplified in Reference 26 (Para. 53.40, Table D-1) to 5 µg/m3 or 7 percent for three collocated samplers.
        2. Comparability: A procedure for testing comparability of PM10 methods is provided. This procedure requires operation of the various devices in the same context (immediate vicinity and time), and a subsequent statistical analysis of measurements. The results are required to correlate 0.97 with previously established reference, with respect to sample masses measured over 24 hours (Ref. 24, Para. 53.34, Table C-4).
        3. Upper capacity limit: All samplers should be capable of measuring 24-hour mass concentrations of at least 300 micrograms per standard cubic meter of air (Ref. 25, Para. 3.1). Filter exchange features can extend the upper capacity for some devices, which use various automatic filter replacement mechanisms to overcome limitations of excess matter collecting on one filter. Thus a given device might be pre-loaded with several filters which will be used sequentially.
        4. Accurate air flow measurement is crucial to the determination of concentration of particulate matter, and sampling devices employ various systems for flow determination. For example, a mass sensor sends a signal to a microprocessor, which makes a determination and either increases or decreases fan speed. Appendix J requires that flow rate be accurate to within 2 percent of a preselected standard over a range of (potential) ambient conditions (Ref. 25, Para. 8.2.2).
      7. Instrument - Manufacturer:
        1. Partisol 2000 - Rupprecht-Patashnick
        2. GMW-1200 - Andersen Instruments, Inc.
        3. Model 600 - Thermo-Environmental Instruments
        4. Model PQ100 Portable - BGI Incorporated
        5. Model 241 series dichotomous sampler - Andersen Instruments, Inc.
        6. Model Partisol-FRM 2000 - Rupprecht - Patashnick
        7. Partisol-Plus Model 2025 - Rupprecht - Patashnick
        8. Model PQ200 - BGI Incorporated
      8. References: 24, 25, 26 (Go to References)

    2. Beta Attenuator Methods (FEM)
      1. Basis: Beta particles (electrons with energies in the 0.01 to 0.1 MeV range) are attenuated according to an approximate exponential function when they pass through particulate deposits on a filter tape. Automated samplers (analyzers) use a continuous filter tape, first measuring the attenuation by the unexposed tape, and then measuring the attenuation after the tape has passed through the ambient air flow. The attenuation measurement converts to a measure of the mass on the filter, so that the filters do not require later laboratory analysis for the mass variable. For some devices, the beta particle source is 14C.
      2. Range: The concentration range is 30 to 300 µg/m3 for test conditions. (Ref. 24, Para. 53.34, Table C-4)
      3. Lower detection limit, or lower quantifiable limit: This limit is not set but is permitted to vary according to filter technology. (Ref. 25, Para. 3.1). An approximate value of 5 µg/m3 is given in Ref. 27.
      4. Temperature tolerance: Samplers must operate over a -30° to +45°C temperature range (Ref. 28, Para. 7.4.7). Some devices are offered with temperature protection features, which are optional.
      5. Known Interference:
        1. Particulate matter may be lost due to filter tape advance and vibration, especially if filter is exposed to warming.
        2. Gaseous species may contaminate filters.
        3. Humidity and absorbed water may be difficult to control during operations.
        4. Meteorological conditions may affect flow rate.
        5. Although on-site real-time mass measurement offers significant improvements over the filter removal and laboratory analysis process, the beta emission and detection process present additional on-site maintenance requirements.
      6. Notes of Interest:
        1. Precision (means agreement among successive measures of equal samples) is defined by EPA as follows: must be 5 µg/m3 for PM10 concentrations below 80 µg/m3 and 7 percent for PM10 concentrations above 80 µg/m3 (Ref. 25, Para. 4.1), but the wording probably means "at least 5 µg/m3." This requirement is simplified in Reference 26 (Para. 53.40, Table D-1) to 5 µg/m3 or 7 percent for three collocated samplers.
        2. Comparability: A procedure for testing comparability of PM10 methods is provided. This procedure requires operation of the various devices in the same context (immediate vicinity and time), and a subsequent statistical analysis of measurements. The results are required to correlate 0.97 with previously established reference, with respect to sample masses measured over 24 hours (Ref. 24, Para. 53.34, Table C-4).
        3. Upper capacity limit: All samplers should be capable of measuring 24-hour mass concentrations of at least 300 micrograms per standard cubic meter of air (Ref. 25, Para. 3.1).
        4. Because of the characteristics of the Beta particles emitters, which emit particles in irregular intervals, or bursts, the accuracy of the devices improves with longer periods of sampling, during which the emission frequency approaches a mean value, and thus detects the "true" ambient concentration, as deposited on the filter. By this same phenomenon, the detection of the "true" ambient concentration will be detected earlier, and more accurately for higher concentrations.
      7. Instrument - Manufacturer:
        1. BAM/GBAM series - Met One Instruments
        2. Model 650 - Thermo-Environmental Instruments, Inc.
        3. Model FH-621-N - Andersen Instruments Inc.
      8. References: 24, 25, 26, 27, 28 (Go to References)

    3. Tapered Element Oscillating Microbalance (TEOM) Methods (FEM)
      1. Basis: Air is drawn through a tapered glass element with a filter attached. The element oscillates according to a characteristic frequency, that decreases as mass accumulates on the attached filter. Measurement of the change in frequency converts to measurement of the accumulated mass.
      2. Range: The concentration range is 30 to 300 µg/m3 for test conditions. (Ref. 24, Para. 53.34, Table C-4).
      3. Lower detection limit, or lower quantifiable limit: This limit is not set but is permitted to vary according to filter technology. (Ref. 25, Para. 3.1). An approximate value of 5 µgm3 is given in Ref. 27.
      4. Temperature tolerance: Samplers must operate over a -30° to +45°C temperature range (Ref. 28, Para. 7.4.7). Some devices are offered with temperature protection features, which are optional.
      5. Known Interference:
        1. Particulate matter may be lost due to vibration, especially if exposed to warming.
        2. Gaseous species may contaminate filters.
        3. Humidity and absorbed water may be difficult to control during operations.
        4. Meteorological conditions may affect flow rate.
        5. Although on-site real-time mass measurement offers significant improvements over the filter removal and laboratory analysis process, the TEOM equipment presents additional maintenance requirements.
      6. Notes of Interest:
        1. Precision (means agreement among successive measures of equal samples) is defined by EPA as follows: must be 5 µg/m3 for PM10 concentrations below 80 µg/m3 and 7 percent for PM10 concentrations above 80 µg/m3 (Ref. 25, Para. 4.1), but the wording probably means "at least 5 µg/m3." This requirement is simplified in Reference 26 (Para. 53.40, Table D-1) to 5 µg/m3 or 7 percent for three collocated samplers.
        2. Comparability: A procedure for testing comparability of PM10 methods is provided. This procedure requires operation of the various devices in the same context (immediate vicinity and time), and a subsequent statistical analysis of measurements. The results are required to correlate 0.97 with previously established reference, with respect to sample masses measured over 24 hours (Ref. 24, Para. 53.34, Table C-4).
        3. Upper capacity limit: All samplers should be capable of measuring 24-hour mass concentrations of at least 300 micrograms per standard cubic meter of air (Ref. 25, Para. 3.1).
      7. Instrument - Manufacturer
        1. Model 1400 - Rupprecht-Patashnick
      8. References: 24, 25, 26, 27, 28 (Go to References)

  2. Particulate Matter - size less than or equal to 2.5 micrometers (PM2.5)

    1. Gravimetric Methods - exchangeable filters (FRM)
      1. Basis: An air pump draws ambient air at a constant flow rate into a specially shaped inlet. Suspended particulate matter is then collected on a filter. Each filter is weighed before and after use, and moisture content of filters is controlled. The total volume of air filtered is known from the constant air flow, and the difference in filter weights is used to calculate the particulate concentration micrograms per cubic meter of air (µg/m3).
      2. Range: The concentration range is 10 to 200 µg/m3 for test conditions. (Ref. 24, Para. 53.34, Table C-4)
      3. Lower detection limit, or lower quantifiable limit: FRM samplers should be able to detect a 24 hour average concentration of 2 µg/m3 (Ref. 28, Para. 3.1).
      4. Temperature tolerance: Samplers must operate over a -30° to +45°C temperature range (Ref. 28, Para. 7.4.7). Some devices are offered with temperature protection features, which are optional.
      5. Known Interference:
        1. Particulates may be lost during filter handling and weighing procedures especially if filter is exposed to warming.
        2. Gaseous species may contaminate filters.
        3. Humidity and absorbed water may be difficult to control both during operations and when handling filters.
        4. Removing filters and transporting to lab for analysis may affect results.
        5. Meteorological conditions may affect flow rate.
      6. Notes of Interest:
        1. Precision for PM2.5 samplers is specified as a 10 percent coefficient of variation or better (Ref. 28, Para. 5). A separate method of calculating precision for particulate samplers is given in Ref 26 (Para. 53.43(c)).
        2. An upper limit for filter mass loading is not given. All samplers are probably able to measure an ambient air concentration of at least 200 micrograms per cubic meter over a 24 hour period (Ref. 28, Para. 3.2).
      7. Instrument - Manufacturer:
        1. Partisol Model FRM 2000 - Rupprecht - Patashnick
        2. Partisol-Plus Model 2025 - Rupprecht and Patashnick
        3. RAAS2.5-100 - Andersen Instruments, Inc.
        4. RAAS2.5-300 - Andersen Instruments, Inc.
        5. PQ200 - BGI, Incorporated
      8. References: 24, 26, 28 (Go to References)

NARSTO Measurement Methods Compendium / Comments?
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