Source Testing of Particulate Matter Emissions from Cotton Harvesters – System Design

Recent air quality legislation has placed increased pressure on agricultural producers in several states across the US. In particular, California removed the exemption for agricultural sources from air quality permitting in 2003. Through the use of inaccurate particulate matter emission factors, agricultural operations have been targeted as significant sources of particulate matter emissions. The emission factors used by regulators in California were developed using techniques with high levels of uncertainty. The objective of this manuscript is to present a novel approach to measuring source emission concentrations from cotton harvesting operations. The proposed sampler design would collect all of the harvested seed cotton, trash, and conveying air at the exit of the conveying ducts used to transport the harvested material to the basket. The air and entrained particulate matter would be separated from the seed cotton and large trash inside a dropper box where isokinetic concentration measurements would be taken at a point just before the air and entrained particulate matter is exhausted to the outside. Subsequent particle size distribution analyses of the particulate matter collected from the isokinetic samples would be used to determine the corresponding PM10, PM2.5, and PM10-2.5 source emission concentrations. Finally, particulate matter emission factors would be calculated (for each size fraction indicator i.e. PM2.5, PM10, or PM10-2.5) on both a lbs/acre and lbs/bale harvested basis. It is expected that the techniques discussed in this manuscript would yield more accurate science based emission factors than the emission factors currently in use.