emission samples were obtained from two medium - sized power plants , one fired with oil and the other with pulverized coal . 
 particles obtained by a miniscale plume stack gas sampler ( mipsgas ) , simulating the dilution process in the plume , were subjected to detailed physical , chemical and biological characterization . 
 studies by scanning electron microscopy and by coulter counter demonstrated that the particles from the oil - fired boiler were considerably larger than the particles from the coal - fired boiler . 
 chemical analyses revealed more organic substances and more s , ni , v , in the oil than in the coal particles . 
 the latter contained a larger proportion of al , si , cl , k , ca , ti , mn , fe , se , rb , y , zr , ba and pb . biological testing revealed a greater acute and subacute toxicity by the intratracheal route in the hamster , a greater toxicity to alveolar macrophages and a greater lung retention of bap coated on the particles from oil combustion than on those from coal combustion . in another sampling line , employed simultaneously with the mipsgas - particulate sampler , 
 the total emissions were collected , i.e. , both particle and gas phase . 
 these samples were used for chemical analyses and ames mutagenicity test . 
 analyses of specific pahs in emissions from both plants demonstrated that concentrations were below the detection limit ( less than 4 ng / m3 of benzo(a)pyrene ) , which is in accord with an efficient combustion of the fuel . 
 the mutagenicity of the samples were below the detection limit of the mutagenicity assay.imagesfigure 4.figure 5 .