Technical Bulletin No. 0085: The Relationship of Particulate Concentration and Observed Plume Characteristics at Combination Wood Fossil Fuel-Fired Boilers (AQTB)

The field work described in this technical bulletin was undertaken to determine the relationship of combination wood and fossil fuel fired boiler plume appearance, or, opacity, and particulate concentration within a spectrum of existing and developing particulate emission regulations. The study was conducted in two locations in the United States, the Middle Atlantic and the Southeast, and involved boilers, one with a precipitator and one with a mechanical collector. Opacity was measured using panels of trained observers making simultaneous readings while in-stack opacity was monitored under steady state emission control conditions. The study findings include the effects of variables such as viewing background and lighting conditions on opacity measurement made by trained human observers. Relationships developed between in-stack measured opacity and simultaneous opacity measurements by trained observers should be helpful in the interpretation of regulations which assume these opacity measurements to be equivalent.