Revisiting the size selective performance of EPA's high-volume total suspended particulate matter (Hi-Vol TSP) sampler

Abstract

Under the National Ambient Air Quality Standard (NAAQS) for airborne lead, measurements are conducted by means of a high-volume total suspended particulate matter (Hi-Vol TSP) sampler. In the decade between 1973 and 1983, there were 12 publications that explored the sampling characteristics and effectiveness of the Hi-Vol TSP, yet there persists uncertainty regarding its performance. This article presents an overview of the existing literature on the performance of the Hi-Vol TSP, and identifies the reported sampler effectiveness with respect to four factors: particle size (reported effectiveness of 7%-100%), wind speed (¡36% to 100%), sampler orientation (7%-100%), and operational state (107%-140%). Effectiveness of the Hi-Vol TSP was evaluated with a solid, polydisperse aerosol in a controlled wind tunnel setting. Isokinetic samplers were deployed alongside the Hi-Vol TSP to investigate three wind speeds (2, 8, and 24 km h ¡1), three sampler orientations (0 , 45 , 90), and two operational states (on, off) for aerosols with aerodynamic diameters from 5 to 35 mm. Results indicate that particle diameter was the largest determining factor of effectiveness followed by wind speed. Orientation of the sampler did not have a significant effect at 2 and 8 km h ¡1 but did at 24 km h ¡1. In a passive state, the Hi-Vol TSP was collected between 1% and 7% of available aerosol depending on particle size and wind speed. Results of this research do not invalidate results of previous studies but rather contribute to our overall understanding of the Hi-Vol TSP's size-selective performance. While results generally agreed with previous studies, the Hi-Vol TSP was found to exhibit less dependence on these four factors than previously reported.

Comparison of current Federal Reference Methods for ambient lead measurements adjacent to a secondary lead smelter

“…Several factors that may result in PM sample measurement inaccuracies have been identified. One factor is that the high-volume technique is known to exhibit some collection efficiency variability due to the effects of differences in wind speed and wind direction (Krug et al 2017;EPA 2007a;Wedding, McFarland, and Cermak 1977). This variability is predominately associated with particle sizes greater than 10 microns in diameter.…”

“…The effect of using various cut points to develop an AF for Pb-PM 10 measurements was examined. The first-pass cut point investigated (0.005 µg/m 3 ) was half that which had been used previously (Cavender and Schmidt 2007;Cavender 2008;Schmidt and Cavender 2008). Excluding these low concentrations resulted in the total number of date-matched pairs to decrease from 358 to 213 and caused the average for the reduced Pb-PM 10 date-matched-paired data set to increase from 62% to 67% of the average for the reduced Pb-TSP date-matched-paired data set.…”

“…Theoretically this should not be possible because the PM 10 technique should capture only a subset of the PM captured by the Pb-TSP sampler. Krug et al (2017) investigated the highvolume TSP sampler's performance and effectiveness with respect to the size of the particles, the wind speed, its orientation (to look at the effects of different wind directions), and its operational state. Significant changes to the TSP's particle capture efficiency were noted for all four of these parameters, with the largest variations observed with the particle diameter than with the wind speed and the smallest variations observed for the operational state.…”

“…Significant changes to the TSP's particle capture efficiency were noted for all four of these parameters, with the largest variations observed with the particle diameter than with the wind speed and the smallest variations observed for the operational state. The referenced Krug et al (2017) paper also reviews and provides summaries of the dozen papers found in the existing literature looking into the performance and effectiveness of the highvolume TSP sampler. It has been recognized that emissions of all Pb particles are a concern regardless of size because of their ability to enter the blood stream and cause adverse health effects (EPA 2007a(EPA , 2007b(EPA , 2008bHenderson, 2008).…”

“…It was indicated that there are limitations and uncertainties in the development and selection of default scaling factors (EPA 2008b). Schmidt and Cavender (2008) concluded that it was unlikely that one generic ratio would allow for accurate estimates of the Pb-TSP concentrations using Pb-PM 10 data at all the sampling sites given the wide spread of the Pb-PM 10 /Pb-TSP ratios. This conclusion was based on analyses of the Pb measurements from colocated Pb-TSP and Pb-PM 10 monitors at 22 EPA Air Quality System (AQS) locations between the years 1993 and 2006 and an additional non-AQS site adjacent to a primary Pb smelter from 1988.…”