Comparison of Real-Time Instruments Used To Monitor Airborne Particulate Matter

Abstract

Measurements collected using five real-time continuous airborne particle monitors were compared to measurements made using reference filter-based samplers at Bakersfield, CA, between December 2, 1998, and January 31, 1999. The purpose of this analysis was to evaluate the suitability of each instrument for use in a real-time continuous monitoring network designed to measure the mass of airborne particles with an aerodynamic diam less than 2.5 µm (PM 2.5 ) under wintertime conditions in the southern San Joaquin Valley. Measurements of airborne particulate mass made with a beta attenuation monitor (BAM), an integrating nephelometer, and a continuous aerosol mass monitor (CAMM) were found to correlate well with reference measurements made with a filter-based sampler. A Dusttrak aerosol sampler overestimated airborne particle concentrations by a factor of ~3 throughout the study. Measurements of airborne particulate matter IMPLICATIONS Regulatory agencies need instruments that can monitor the concentration of PM 2.5 in real time so that public health advisories can be issued during severe pollution events. Three types of continuous, real-time instruments have been identified that can function in a routine PM 2.5 monitoring network during winter conditions encountered in central California: the BAM, the integrating nephelometer, and the CAMM. Each instrument performed well within a broad PM 2.5 concentration range composed of both volatile and semi-volatile particulate matter.made with a tapered element oscillating microbalance (TEOM) were found to be lower than the reference filterbased measurements by an amount approximately equal to the concentration of NH 4 NO 3 observed to be present in the airborne particles. The performance of the Dusttrak sampler and the integrating nephelometer was affected by the size distribution of airborne particulate matter. The performance of the BAM, the integrating nephelometer, the CAMM, the Dusttrak sampler, and the TEOM was not strongly affected by temperature, relative humidity, wind speed, or wind direction within the range of conditions encountered in the current study. Based on instrument performance, the BAM, the integrating nephelometer, and the CAMM appear to be suitable candidates for deployment in a real-time continuous PM 2.5 monitoring network in central California for the range of winter conditions and aerosol composition encountered during the study.

Characterizing the range of children's air pollutant exposure during school bus commutes

“…Impactors were used to perform the necessary size cut and the particle mass concentration was determined by measuring the intensity of the 901 scattering of light from a laser diode. However, as reported elsewhere (Ramachandran et al, 2000;Chung et al, 2001;Yanosky et al, 2002;Fitz et al, 2003), DustTrak measurements were generally higher than the integrated gravimetric method and to provide absolute concentrations comparable to other studies, PM 2.5 mass data reported here are from the Harvard Impactors. Data collected with the DustTrak were only used on a relative basis during window position tests, when real-time information was required.…”

Instrument Busy Time and Mass Measurement using Aerosol Time-of-Flight Mass Spectrometry

“…Continuous PM 2.5 , particulate matter with aerodynamic diameter, D a , less than 2.5 µm, mass concentrations measured using the CAMM and BAMs were evaluated by the BIIS project team (Chung et al 2001a). They found that 24-h PM 2.5 concentrations measured with both BAMs correlated well (R 2 ≥ 0.99) with results from a Federal Reference Method (FRM) sampler.…”

“…MOI samplers were operated simultaneous with ATOFMS instruments during 7 intensive operating periods (IOPs) (Chung et al 2001a(Chung et al , 2001b. The IOPs were on 14 January (BAK01), 15 January (BAK02), 16 January (BAK03), 19 January (BAK04), 21 January (BAK05), 22 January (BAK06), and 23 January (BAK07).…”

“…The Bakersfield Instrument Intercomparison Study (BIIS) experiment was conducted in Bakersfield, CA, from November 1998 to February 1999 (Chung et al 2001a(Chung et al , 2001b). An objective of this study was to evaluate the relative performance of commercially available real-time particle samplers with filterbased particle sampling methods.…”

Deposition and Removal of Fugitive Dust in the Arid Southwestern United States: Measurements and Model Results

“…By volume, the standard consists of 1-3% particles with diameters less than 1 m, 36 -44% with diameters less than 4 m, 83-88% with diameters less than 7 m, and 97-100% with diameters less than 10 m. Niu et al 25 found that in comparing data from four DustTraks collocated in an indoor environment, the interinstrument variability was a reasonable 3%. Several authors have also reported that DustTrak measurements correlate well with filter-based measurements of diesel exhaust, 26 ambient urban particulate matter, 27 and indoor airborne particles, 25 though in all cases, investigators noted that the DustTrak deviated from filter-based measurements by a factor that depends on the nature of the aerosol measured. One shortcoming of using a nephelometer-style instrument is that light scattering response to changes in mass concentration can depend strongly on particle composition as well as particle size.…”