Title: Particulate Matter Sampler Errors Due to the Interaction of Particle Size and Sampler Performance Characteristics: Ambient PM2.5 Samplers Authors
|Parnell, JR., Calvin - TEXAS A&M UNIVERSITY|
|Shaw, Bryan - TEXAS A&M UNIVERSITY|
|Lacey, Ronald - TEXAS A&M UNIVERSITY|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 2, 2006
Publication Date: February 15, 2007
Citation: Buser, M.D., Parnell, Jr., C.B., Shaw, B.W., Lacey, R.E. 2007. Particulate matter sampler errors due to the interaction of particle size and sampler performance characteristics: Ambient PM2.5 samplers. Transactions of the ASABE. 50(1):241-254. Interpretive Summary: Agricultural operations are encountering difficulties complying with the current air pollution regulations for particulate matter (PM). These regulations are based on the National Ambient Air Quality Standards (NAAQS), which set maximum limits for ambient PM based on protecting public health. There are several errors associated with the current air pollution rules and regulations established by the EPA which should be minimized to assure equal regulation of air pollutants between, and within, all industries. Further, the errors associated with PM2.5 (PM with an aerodynamic diameter less than or equal to 2.5 um) ambient air samplers could lead regulatory agencies to force some industries to implement economically burdening abatement controls that will not significantly reduce PM2.5 emissions in the air shed. For instance, the data provided in this manuscript shows that using an EPA approved PM2.5 ambient air sampler to measure the PM less than 2.5 microns being emitted from an agricultural operation could result in actual concentrations being over-reported by a factor of 14. The bottom line associated with this series of manuscripts is that not all industries are being equally regulated in terms of PM and that all industries should be concerned with the current site-specific regulations implemented by EPA and enforced by SAPRAs.
Technical Abstract: The National Ambient Air Quality Standards (NAAQS) for particulate matter (PM) in terms of PM2.5 are ambient air concentration limits set by the EPA that should not be exceeded. Further, some State Air Pollution Regulatory Agencies (SAPRAs) utilize the NAAQS to regulate criteria pollutants emitted by industries by applying the NAAQS as property line concentration limits. Prior to, and since the inclusion of the PM2.5 standard, numerous journal articles and technical references have been written to discuss the epidemiological effects, trends, regulation, and methods of determining PM2.5. A common trend among many of these publications is the use of samplers to collect information on PM2.5. Often, the sampler data is assumed to be accurate measures of PM2.5. The fact is that issues such as sampler uncertainties, environmental conditions, and material characteristics for which the sampler is measuring must be incorporated for accurate sampler measurements. The focus of this manuscript is on the errors associated with particle size distribution (PSD) characteristics of the material in the air that is being sampled, PM2.5 sampler performance characteristics, the interaction between these two characteristics, and the effect of this interaction on the regulatory process. Theoretical simulations were conducted to determine the range of errors associated with this interaction for the PM2.5 ambient air samplers. Results from the PM2.5 simulations indicated that a source emitting PM characterized by a mass median diameter (MMD) of 20 um and a geometric standard deviation (GSD) of 1.5 could be forced to comply with a PM2.5 standard that is 14 times more stringent than that required for a source emitting PM characterized by a MMD of 10 um and a GSD of 1.5 and 59 times more stringent than that required for a source emitting PM characterized by a MMD of 5.7 um and a GSD of 1.5. Therefore, in order to achieve equal regulation among differing industries, PM10 and PM2.5 measurements MUST be based on true concentration measurements.