Emission of PM_<10> from co-firing of coal and cedar was investigated. The reaction conditions were selected as: 1450℃, air and a residence time of ca. 3 seconds. The results indicate that, for the combustion of cedar alone, many PM_1, was produced consisting of condensed metallic vapors. During the co-firing of coal and cedar at a mass ratio of 90:10, little changes were observed for PM_<10>. With the proportion of cedar increased, less PM_<10> was however emitted since more the larger aggregates were formed through the interaction between coal minerals and cedar minerals
