Large Particle Penetration During PM₁₀Sampling

Abstract

The objective of the present study was to characterize the performance of a federal reference method (FRM) PM 10 sizeselective inlet using analysis methods designed to minimize uncertainty in measured sampling efficiencies for large particles such as those most often emitted from agricultural operations. The performance of an FRM PM 10 inlet was characterized in a wind tunnel at a wind speed of 8 km/h. Data were also collected for 20 and 25 mm particles at wind speeds of 2 and 24 km/h. Results of the present sampler evaluation compared well with those of previous studies for a similar inlet near the cutpoint, and the sampler passed the criteria required for certification as a FRM sampler when tested at 8 km/h. Sampling effectiveness values for particles with nominal diameters of 20 and 25 mm exceeded 3% for 8 and 24 km/h wind speeds in the present study and were statistically higher than both the "ideal" PM 10 sampler (as defined in 40 CFR 53) and the ISO (1995) standard definition of thoracic particles (p < 0.05) for 25 mm particles leading to the potential for significant sampling bias relative to the "ideal" PM 10 sampler when measuring large aerosols. INTRODUCTIONExposure to high concentrations of thoracic aerosols has been linked to significant, negative health effects, including increased incidence of asthma, cardiovascular disease, mortality, and morbidity. The National Ambient Air Quality Standards (NAAQS) were established to protect public health and welfare by limiting the concentrations of ambient pollutants to which the public is exposed. The NAAQS for PM 10 is intended to protect the public against high concentrations of thoracic particles. Compliance with the NAAQS is demonstrated through use of ambient particulate matter (PM) monitors that measure 24-h integrated concentrations of pollutants. Specialuse monitors may also be placed at or near the property lines of some sources to ensure that emissions from that source do not lead to public exposure to concentrations exceeding the NAAQS.When monitoring PM 10 concentrations for regulatory purposes, it is important that measured concentrations of PM 10 are representative of concentrations of particles that have the potential to cause adverse health effects. PM 10 samplers are designed to allow those particles expected to penetrate past the larynx of the human respiratory system to penetrate the sampler precollector and deposit on a filter. The American Conference of Governmental Industrial Hygienists (ACGIH) has defined the "thoracic fraction" of particles, and that definition has been adopted as a standard by International Standards Organization (Figure 1; ISO 1995).In the Code of Federal Regulations (CFR), the U.S. Environmental Protection Agency (USEPA) has defined the performance of an "ideal" PM 10 sampler (Figure 1; 40 CFR 53.43) that "approximates the penetration of particles into the human respiratory tract" (40 CFR 53.40(d)). The fractional penetration, or sampling efficiency, of the "ideal" PM 10 sampler closely matches that of the ACGIH/IS...

Performance of two shrouded probes for the collection of liquid aerosols in a wind tunnel optimized for high air speeds

“…A HEPA filter was fitted at the last rectangular section to capture uranine particles at the end of the wind tunnel and prevent air contamination (Faulkner, Smith, and Haglund 2014). A portable hot film thermal anemometer (Model 8360, TSI Inc., Shoreview, MN, USA) was installed at the exit of the ellipsoid duct to measure wind velocity and adjust the air speed by changing the VFD controller of the discharge blower.…”

“…The shrouded probe Model A and Model B were tested at 57 L/min flow rate. Preparation and generation of liquid uranine aerosols (LUA) Uranine (Fluorescein disodium salt C 20 H 10 Na 2 O 5 , TCI Inc. New Brunswick, NJ 08901-3605) and oleic acid (Octadecenoic acid, C 18 H 34 O 2 , Spectrum Chemical Manufacturing Corp., Gardena, CA, USA) at a mass (uranine) to volume (oleic acid) ratio of 8.93 were used for making the solutions for 10 mm liquid particles (Faulkner, Smith, and Haglund 2014). An HPLC pump (High Performance Liquid Chromatography, Series 1500, ChromTech, Inc., Apple Valley, MN, USA) was used to transfer the uranine solution to the nozzle of a vibrating orifice aerosol generator (VOAG; model 3450, TSI, Inc., Shoreview, MN, USA) at a constant flow rate (0.225 mL/min).…”

“…After each set, the inner walls of both probes were thoroughly washed with measured amounts of ethyl alcohol and distilled water and the solutions were analyzed. Similarly, the fluorescein from the filters was also eluted in measured amounts of ethyl alcohol and water and the resulting solutions were analyzed with a Barnstead fluorometer to measure the Fluorescent Intensity Unit (FIU) values (Faulkner, Smith, and Haglund 2014).…”

“…Since liquid particles stretch after entering the APS, and result in biased size measurement, microscopic measurement was applied to evaluate the APS performance for particle size determination. In this case, liquid particles were impacted on cleaned slides coated with NyeBar Type Q (0.2%; Nye Synthetic Lubricants; Fairhaven, MA, USA) and observed under microscope (Faulkner, Smith, and Haglund 2014). Using the flattening coefficient of 1.2 resulted in the particle size of 12.0 lm for the liquid aerosols generated by the VOAG.…”

Effect of convergence angle on impactor performance

“…Based on quality control parameters established by the authors (Faulkner et al 2014), a fluorometric signal is considered reliable when the FIU value of the test solution is at least twice the FIU value of the 0.01 mole/L ammonium hydroxide solvent. Test durations varied from 1 to 2 hours to achieve a sufficient fluorometer reading.…”