Coal-fired fine particles were generated by a coal-fired boiler burning anthracite. Fig. 3a shows the particle size distribution measured by the ELPI, and displays a unimodal distribution in the number concentration, which may be attributed to the combustion
condition, coal and boiler type employed. As can also be seen from Fig. 3a, the fine particles were mostly in the submicron size range with maximum number concentration at 0.07 lm, and the median value of the size distribution at 0.045 lm.