DIESEL EXHAUST QUANTIFICATION BY SCANNING ELECTRON-MICROSCOPE WITH SPECIAL EMPHASIS ON PARTICULATE SIZE DISTRIBUTION

The purpose of this study was to investigate the potentials of electro n microscopy to quantify diesel exhaust emission from work environment s, where the aerosol consists of both diesel fumes and dust particles from pollutant sources. The mass and particles concentrations as well as size distributions were investigated. The size distribution consist s of two modes: a group of particles with D-min < 0.7 and a group of p articles with D-min > 1.0 mu m, respectively. The D-min in the range 0 .7-1.0 mu m should be regarded as an interval where there is an overla pping. To distinguish between organic and non-organic components of th e particulate, low-temperature plasma ashing was made. This is a very slow oxidizing process that does not affect or disturb non-oxidizable material. The diesel fumes in the samples constitute only a small shar e of the total mass, while diesel fumes dominate by numbers in those s amples. A big difference is observed between the number of concentrati ons for non-ashed and ashed samples, respectively. However, no signifi cant differences are observed between the volume diagram for non-ashed and ashed samples. One should therefore consider the number of concen trations of particles below 1 mu m in diameter rather than the gravime tric concentrations when studying exposure level for diesel exhaust. C opyright (C) 1996 Elsevier Science B.V.