|Parnell, Jr., Calvin|
Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: 7/19/2005
Publication Date: 11/10/2005
Citation: Wanjura, J.D., Buser, M.D., Whitelock, D.P., Capareda, S., Parnell, Jr., C., Shaw, B., Lacey, R. 2005. A method of estimating FRM PM10 sampler performance characteristics using particle size analysis and collocated TSP and PM10 samplers. American Society of Agricultural and Biological Engineers. Paper No. 054015. Interpretive Summary: The national ambient air quality standards in the US include a particulate matter standard for limiting the annual and 24 hour average concentrations of PM10. PM10 refers to dust particles having diameter less than or equal to a nominal 10 micrometers. Some states use EPA approved PM10 samplers at the property line of agricultural and industrial sources of particulate matter to determine the amount of PM10 that is being emitted from the source. In order for all industries to be equally regulated, the PM10 samplers must accurately measure true concentrations of PM10. Previous research has shown that the PM10 sampler approved by the EPA does not accurately measure PM10 concentrations from all sources. Researchers have stated several problems with the operation of the EPA approved PM10 sampler causing it to inaccurately measure PM10 concentrations. Included in the problems identified for causing inaccurate concentration measurements is a potential shift in the sampler performance criteria specified by the EPA. The sampler performance criteria describe how much of a particular size of dust that the sampler will allow to pass through the inlet of the sampler and be deposited on the filter for concentration analysis. It has been previously assumed that the performance criteria of the EPA approved PM10 samplers do not change. The results of this work show that the performance characteristics of the EPA approved PM10 sampler do shift from those specified by the EPA. Substantial shifts in the performance characteristics caused the PM10 samplers to over state true PM10 concentrations by as much as 286%.
Technical Abstract: In the US, regional air quality compliance with national ambient air quality standards (NAAQS) for PM10 is based on concentration measurements taken by federal reference method (FRM) PM10 samplers. The EPA specifies the performance characteristics of the FRM PM10 sampler by defining ranges for the parameters characterizing the lognormal penetration curve of the sampler. The parameters characterizing the penetration curve of the FRM PM10 sampler are the cutpoint and slope with specified ranges of 10 ± 0.5 um and 1.5 ± 0.1, respectively. It is assumed by the EPA that the performance characteristics of the FRM PM10 sampler do not change. Several sources have observed errors in the concentrations measured by the FRM PM10 samplers. These sources state a range of possible reasons for the measurement errors observed including: 1) allowing a tolerance of ± 0.5 um for the 10 um cutpoint; 2) cutpoint deviations, beyond the established tolerances, associated with various field application parameters; 3) inadequate restrictions on internal particle bounce; 4) surface overloading; 5) soiling of certain types of PM10 inlets; and 6) losses of semivolatile components. Limited work has been conducted on quantifying the shift in the performance characteristics of the FRM PM10 sampler operating under field conditions. Recent work at a south Texas cotton gin showed that true PM10 concentrations were 55% of the concentrations measured by the FRM P10 sampler. If the FRM PM10 sampler were operating within the performance criteria range specified by the EPA, the concentrations measured by the FRM PM10 sampler would be within approximately 12% of the true PM10 concentrations. These results show that there is a clear shift in the performance characteristics of the FRM PM10 sampler. The focus of this work was to quantify the shifts in the cutpoint and slope of the penetration curve of the FRM PM10 sampler. Results of this work show that the cutpoint and slope of the FRM PM10 sampler shift substantially when exposed to agricultural particulate matter. The cutpoints and slopes of the FRM PM10 sampler used in this research ranged from 13.8 to 34.5 um and 1.7 to 5.6, respectively. These shifts in the cutpoint and slope of the FRM PM10 sampler resulted in the over statement of true PM10 concentrations in the range of 145 to 286%.