Measurement of Visible Dust Emissions During Almond Nut-Picking Operations at Various Harvester Settings

Abstract

The U.S. Environmental Protection Agency (EPA) Method 9 and the Digital Compliance Opacity Technique (DCOT) were both used to measure relative dust intensity at different almond harvester settings and evaluate dust reduction levels while using a “low-dust” harvester. A conventional harvester at standard settings (3 mph and 900 rpm fan speed) generated visible dusts with 23.3% - 29.0% opacity. A low-dust harvester at similar settings produced an average of 13.94% dust opacity. The average dust intensity relative to the conventional was reduced by 45.5% for low-dust harvesters operated at lower ground speeds, 58% by lowering the fan speed, and 66.4% by turning off the separation fan. At this stage, opacity-based techniques can potentially be adapted as a screening tool for identifying best management practices (BMP) of the almond industry in reducing harvest dusts, rather than to solely rely on Federal Reference Method (FRM) mass-based techniques.