ARS | Publication request: Particulate Emission Profile of a Cotton Gin

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 2, 2008
Publication Date: April 15, 2008
Citation: Hughs, S.E., Armijo, C.B., Whitelock, D.P., Buser, M.D. 2008. Particulate emission profile of a cotton gin. Applied Engineering in Agriculture. 24(2):145-151.

Interpretive Summary: Cotton gins emit particulate matter (PM) as part of the ginning process. The Environmental Protection Agency (EPA) regulates PM with National Ambient Air Quality Standards (NAAQS) that all regions of the US are required to meet. The PM of concern under the NAAQS for cotton gins are PM10 (particles with an aerodynamic diameter less than or equal to a nominal 10µm) and PM2.5 (particles with an aerodynamic diameter less than or equal to a nominal 2.5µm). The EPA has established emission factors for PM per bale from stack sampling data for cotton gins. The Clean Air Act (CAA) has established that PM10 and PM2.5 boundary line concentrations cannot exceed 150 and 65 µg/m3 respectively. The EPA emission factors are then sometimes used by regulators in EPA approved modeling programs to predict boundary line PM concentrations for cotton gins as related to CAA established standards. These EPA models were developed to be used for industries with emission points from stacks that are several hundred feet tall. Typical PM emission points from cotton gins are only 30 to 40 ft tall and the EPA models significantly over predict gin property boundary line PM concentrations based on established emission factors. The objective of this study was to measure boundary line concentrations through an entire ginning season for later use in developing a realistic PM concentration prediction model for cotton gins. Results showed that average 24 hr PM10 and PM2.5 concentrations at the boundary downwind for the gin ranged from 4.9 to 39.7 µg/m3 and 0.02 to 0.92 µg/m3, respectively. These levels are significantly below the maximum levels established by the CAA. These data will be useful in future development of a realistic model of gin emissions.

Technical Abstract: PARTICULATE MATTER (PM) IS ONE OF SIX CRITERIA POLLUTANTS REGULATED BY THE ENVIRONMENTAL PROTECTION AGENCY (EPA) WITH NATIONAL AMBIENT AIR QUALITY STANDARDS (NAAQS). IN GENERAL, PM IS THE ONLY AIR POLLUTANT OF CONCERN EMITTED FROM COTTON GINS. THE EPA HAS NAAQS FOR PM10 (PARTICLES WITH AN AERODYNAMIC DIAMETER LESS THAN OR EQUAL TO A NOMINAL 10 µM) AND PM2.5 (PARTICLES WITH AN AERODYNAMIC DIAMETER LESS THAN OR EQUAL TO A NOMINAL 2.5 µM). THE EPA HAS PROMULGATED EMISSION FACTORS FOR PM PER BALE IN AP-42 FOR GINS WITH SPECIFIED EMISSION CONTROLS. SOME REGULATORS HAVE USED THESE AP-42 EMISSION FACTORS IN EPA¿S INDUSTRIAL SOURCE COMPLEX- SHORT TERM 3 (ISC-ST3) MODEL TO PREDICT BOUNDARY LINE PM CONCENTRATIONS FROM COTTON GINS. RESULTS OF THE ISC-ST3 MODEL ARE KNOWN TO BE VERY CONSERVATIVE AND DO NOT ACCURATELY PREDICT PM BOUNDARY LINE CONCENTRATIONS FOR LOW LEVEL AGRICULTURAL SOURCES SUCH AS COTTON GINS. THERE IS, HOWEVER, INSUFFICIENT BOUNDARY LINE CONCENTRATION MEASUREMENT DATA TO DEVELOP MORE ACCURATE MODELS FOR COTTON GINS. THE OBJECTIVE OF THIS STUDY WAS TO MEASURE BOUNDARY LINE AS WELL AS INTERMEDIATE PM CONCENTRATIONS THROUGH THE GINNING SEASON FOR LATER USE IN DEVELOPING A REALISTIC PM CONCENTRATION PREDICTION MODEL FOR COTTON GINS. A MONITORING PROTOCOL WAS DEVELOPED THAT SAMPLED PM CONCENTRATIONS AND ON-SITE WEATHER CONDITIONS AT PERIODIC INTERVALS THROUGH THE ENTIRE 2004 GINNING SEASON. RESULTS SHOWED THAT AVERAGE 24 H PM10 AND PM2.5 DOWNWIND BOUNDARY CONCENTRATIONS RANGED FROM 4.9 TO 39.7 µG/M3 AND 0.02 TO 0.92 µG/M3, RESPECTIVELY. THESE LEVELS ARE SIGNIFICANTLY BELOW THE CLEAN AIR ACT 24-HR PM10 AND PM2.5 STANDARD OF 150 AND 65 µG/M3 RESPECTIVELY.