EMISSION FACTORS FOR FIRST- AND SECOND-PICK PIMA COTTON

摘要

EPA's Region 9, which includes the major Pima production areas of California and Arizona, raised the concern of possible emission factor differences between first- and second-pick Pima cotton. Anecdotal evidence indicated that some complaints of excessive paniculate emissions from Pima gins have arisen from the processing of second-pick cotton. A large amount of emission factor information has been developed over the past 20 years for cotton gins. While some of these data probably include some second-pick upland cotton, most of the upland cotton is harvested once-over with no second picking. There have also been emission factor data gathered for Pima gins, but none of these data can be verifiably attributed to second-pick Pima cotton. Due to the market value of the Pima fiber, there is a significant amount of second-pick Pima cotton ginned each year in EPA Region 9. A study was conducted at a commercial roller gin during the 2001 ginning season to determine what differences there were, if any, between the emission factors for first- and second-pick Pima cotton. Source testing was conducted on the first seed-cotton cleaning and drying system, which is one of the heaviest in terms of paniculate emissions. This replicated source test showed that all measured emission parameters were lower for second-pick Pima cotton. This result indicates that there is no need for separate paniculate emission factors for first- and second-pick Pima. This test also indicates that emissions determined by current EPA-approved source sampling methods may be overestimating emission levels by as much as 1.5 times. A final result is that the levels of PM{sub}2.5 (particles whose diameter is less than or equal to 2.5 μm) are less than 0.5% of the total emissions for either first- or second-pick Pima.