二次元風向風速度数分布の等確率楕円に基く大気汚染曝露ゾーニング

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Elliptically-shaped exposure zones were assigned to 35 air-monitoring stations in the Tokyo metropolitan region. Each zone was a similar figure of an ellipsoidal isopleth of the two-dimensional frequency distribution of daily wind velocity a year. The size of the zone was determined by multipling the isopleth plane of mean plus one standard deviation of wind velocity by c, where c is a scaling factor to transform the probability isopleth into the geographic zone, being itself in a dimension of time. The zone was placed in position to the leeward of the station at the coordinates of the average wind vector multiplied by c. On this placement the major axis of the zone was directed consistently to the direction of the maximum standard deviation of wind velocity. The value of c, which was found out as the supremum value to maximize an entire area of all zones, excluding an overlap of any adjacent two zones, was 600[sec]by m. k. s. unit system.This zoning decides a geographic boundaries, in which direct measurments of air pollution may give an expected exposure level in the resident populations. A combined air pollution index, i. e., PI, was calculated from the monthly average concentrations of 6 pollutants by the equation PI=0.46SO2[pphm]+0.23NO[pphm]+0.25NO2[pphm]+0.27CO[ppm]-0.23Ox[pphm]+0.052Dust[mg/100m3]-2.19, and its annual average, PI, was available for a “dose” variable in the exposure zone. An “effect” variable was evaluated by the crude mortality rate from lung cancer, D[per 105 population], which was calculated from the area-weighted-average of the mortality rates reported from the local health departments located in the area of the exposure zone. There was a positive association between PI and D with a significant correlation coefficient r=0.610 (p<0.001) and a linear regression equation D=12.8-3.33PI.
日本衛生学会の論文

二次元風向風速度数分布の等確率楕円に基く大気汚染曝露ゾーニング

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