| Autor: |
Lang, J. M., Parnell, C. B., Wanjura, J. D., Shaw, B. W. |
| Zdroj: |
Proceedings of the Beltwide Cotton Conferences: Cotton Ginning Conference; Jan 3-6, 2006 San Antonio, TX, p682-688, 7p, 6 Charts |
| Abstrakt: |
The EPA is in the process of promulgating a new National Ambient Air Quality Standard (NAAQS) for concentrations of particulate matter (PM) in the size range of 2.5 to10 micrometers aerodynamic equivalent diameter. PM in this size range is referred to as PM coarse (PMc). The proposed primary PMc NAAQS will be set at 70 μg/m3 (24 hour average). This NAAQS is less than 50% of the current PM10 NAAQS of 150 μg/m3 and it is slightly higher than the PM2.5 NAAQS of 65 μg/m3. There are two regulatory uses of the NAAQS. One is to determine the attainment status of an area. Sufficient numbers of concentration measurements exceeding the NAAQS can result in the designation of an area as being in non-attainment. The second use of the NAAQS is as a ‘concentration not to be exceeded’ at or beyond the property line. The second use of the NAAQS can be extremely detrimental to agricultural operations especially if the PMc concentrations determined through modeling or measurement are incorrect. Currently there are no federal reference methods (FRM) for measuring PMc concentrations. The proposed method for determining PMc concentrations is to subtract FRM PM2.5 concentration measurements from FRM PM10 concentration measurements. This method is referred to as the ‘difference’ method. It is likely that the use of this method will result significant errors in PMc concentration determinations. FRM PM2.5 and PM10 samplers have been shown to exhibit sampling errors when sampling PM emissions from agricultural operations due to the interaction between the sampler and the sampled particulate matter. PM emitted by cotton gins typically has a mass median diameter (MMD) on the order of 18 μm with a geometric standard deviation (GSD) of approximately 2.0. A small percentage of the PM emitted by cotton gins is PM2.5. Because of the large size of PM emitted by cotton gins (compared to PM emitted from urban sources), 145 to 148 μg/m3 would correspond to the correct PMc concentration for a PM10 concentration of 150 μg/m3. The difference is less than the uncertainty associated with FRM PM10 measurements. The work presented in this manuscript points out that any PMc NAAQS less than 150 μg/m3 will result in unjustified limits of property line concentrations for agricultural operations including cotton gins. Problems associated with the implementation of the proposed PMc NAAQS as a property line concentration limit for cotton gins is also addressed. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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