Abstract
In order to clarify the dispersion properties of suspended particulate matter (SPM) in the vicinity of the Meishin expressway, a) the relationship between SPM concentration and the traffic volume of each type of automobile was studied, b) the density distribution of each size of particle was compared with that of nitrogen dioxyde (NO2), Which was the most representative gaseous pollutant from mobile sources, and c) the actual concentrations of particles were compared with the concentrations calculated by the Tokyo Metropolitan Government (TMG) dispersion model in which the effect of gravity on the particles was included. The results were as follows;1) A statistically significant and positive correlation were shown only between the traffic volume of large vehicles and the concentrations of fine particles under 1.6μm.2) At all the measured points, fine particles under 0.7μm in diameter accounted for 44.8% to 65.8% of the total SPM. It was observed that these particles showed a distinct concentration-distance profile with the increase of the average wind velocity.3) As the particle size became smaller, the correlation coefficient between the concentrations of particles and NO2 concentrations became larger. In the case of fine particles under 5.4μm in diameter, the coefficient of correlation was extremely high and was statistically significant.4) In the case of fine paricles under 5.4μm in diameter, the coefficient of correlation between the measured and calculated concentration of each size of particle was extremely high and was statistically significant. In accordance with the facts described above, it was suggested that the dispersion behavior of fine particles under 1.6μm could be well explained in the same manner as gaseous pollutants, and it was proved that these particles were derived from large vehicles with diesel engines.
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More From: Nippon Eiseigaku Zasshi (Japanese Journal of Hygiene)
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