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United States Department of Agriculture

Agricultural Research Service

Research Project: AIR QUALITY ISSUES RELATED TO AGRICULTURAL OPERATIONS AND PROCESSES Title: Determining crustal exclusion for cotton gins

Authors
item Lange, J - TEXAS A&M UNIVERISTY
item Lacey, R - TEXAS A&M UNIVERSITY
item Wanjura, John
item Parnell, JR., Calvin - TEXAS A&M UNIVERSITY

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: February 19, 2007
Publication Date: June 20, 2007
Citation: Lange, J.M., Lacey, R.E., Wanjura, J.D., Parnell, Jr., C.B. 2007. Determining crustal exclusion for cotton gins. In: Proceedings of the National Cotton Council Beltwide Cotton Conferences, January 9-12, 2007, New Orleans, Louisiana. 2007 CDROM. p. 1553-1560.

Interpretive Summary: When the proposed update to 40 CFR Part 50 was first released in 2006, there was mention of agricultural sources being exempt from the National Ambient Air Quality Standards (NAAQS). The proposed exemption was due to the fact that agricultural particulate matter is mostly crustal or, as defined by the EPA, particles of geologic origin (soil). Crustal particles are those that are not associated with health effects in the coarse size range of 2.5 to 10 micrometers. When the final version of 40 CFR Part 50 was released later the same year, this exemption had been removed and EPA chose to promulgate a PMc NAAQS of 150 ug/m3 and to use the concentration measured by Federal Reference Method PM10 samplers as the indicator for PMc. It is likely that within the next 5 years EPA will promulgate a PMc NAAQS lower than the current 150 ug/m3 and would consider a crustal credit for agricultural sources for future versions of 40 CFR Part 50. If this concept were to be adopted, agricultural sources would only be regulated on the mass fraction of PMc emitted that was not considered to be crustal. This could aid in the permitting and regulation of all agricultural sources emitting PMc. For example, if a cotton gin were required to meet an off-property PMc concentration of no more than 150 ug/m3 (NAAQS) and had a measured or modeled downwind concentration of 200 ug/m3, the gin would be required to install additional controls. However, if it were determined that fifty percent of the PMc was crustal, the cotton gin could be given a fifty percent credit and would likely be regulated based on 100 ug/m3. Since there is no objective scientific method for quantifying the mass fraction of crustal PM in the measured or modeled PMc concentrations, a standard methodology to determine the percentage of crustal material downwind from an agricultural facility is needed. This paper outlines the protocol to be used for determining a definition of the crustal fraction of PMc as well as the methodology to determine the mass fraction of crustal in the PMc emissions from cotton gins.

Technical Abstract: During the development of the latest revision for the National Ambient Air Quality Standard for particulate matter (PM), the EPA considered excluding the crustal component of PM in the course size range of 2.5 to 10 micrometers aerodynamic equivalent diameter (AED) for agriculture and mining PM emissions. It was reported that public exposure to concentrations in the crustal fraction of the PM coarse (PMc) emitted from agricultural sources was not associated with health effects. The final version of 40CFR50 did not include an exclusion for the crustal fraction of PMc. EPA defines the crustal fraction of PMc as PM derived from soil. If the crustal credit were to be put into effect, all agricultural facilities, including cotton gins, would likely benefit. For example, if a cotton gin were required to meet an off-property PMc concentration of no more than 150 ug/m3 and had a measured or modeled downwind concentration of 200 ug/m3, the gin would be required to install additional controls. However, if it were determined that fifty percent of the PMc was crustal, the cotton gin could be given a fifty percent credit and would likely be regulated based on 100 ug/m3. Currently, there is no objective scientific method for quantifying the mass fraction of crustal in the measured or modeled PMc concentrations. Historically, PM speciation studies have focused on urban PM sources. More speciation data are needed for agricultural sources, such as cotton gins, in order to obtain credit for the crustal fraction. More importantly, a standard methodology is needed in order to determine the percentage of crustal material downwind from cotton gins and other agricultural operations. This paper outlines a protocol which can be used for determining a definition of the crustal fraction of PMc as well as the methodology to determine the mass fraction of crustal in the PMc emissions from cotton gins and other agricultural operations.

Last Modified: 12/27/2014
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