Back in January of this year, I discussed cyclone repair and maintenance in order to minimize particulate emissions from cotton gins. This month I want to talk about the particulate that comes out of the gin cyclone exhausts that state and Federal regulators are interested in counting. The Environmental Protection Agency (EPA) has long listed atmospheric levels of particulate (some might call it dust) as a concern for reasons of human health. Since 1987, the EPA has had standards in place for allowable levels of particulate whose diameter is 10 microns (PM10) or less.
For comparison, human hair ranges from approximately 17 to 180 microns in diameter, depending on a person’s age and hair color. Regulators have long been using established air pollution emission factors (AP-42) established by the EPA to regulate particulate. Since 1996, the AP-42 emission factor listed for cotton gins with cyclones on all exhausts has been 0.82 pounds per bale of PM10 and 2.4 pounds per bale total particulate.
In 2006, the EPA started implementing its more stringent 2.5 micron (PM2.5) particulate matter standard and began to set emission limits. Regulators initially estimated the PM2.5 emissions from cotton gins with cyclones on all exhausts to be 36 percent of the AP-42 total particulate or about 100 percent of the PM10 emission factor, which was 0.82 pounds per bale.
Many of you have already heard progress reports at the Beltwide and gin association meetings on how a task force was assembled in 2007. That task force was headed by the USDA-ARS and Oklahoma State University researchers over the next four years to do an accurate estimate of PM2.5 particulate emissions from cotton gins.
The discussion of all these numbers can be very dry and boring, but the upshot of all this is that a realistic cotton gin emission factor estimate for PM2.5 should come down within shouting distance of about an average of 0.10 pounds per bale. This number is lower than the original EPA estimate of 0.82 pounds per bale and is an indicator that gins do not emit a significant amount of PM2.5 and will not be a significant concern for future regulatory control.
Ed Hughs is Director of the Southwest Ginning Research Laboratory in Mesilla Park, N.M. Contact him at (575) 526-6381 or firstname.lastname@example.org.