In order to examine the actual conditions of air pollution by suspended particulate matter (SPM) due to diesel exhaust, traffic characteristics, weather conditions and SPM concentrations were measured in the vicinity of Kusatsu Parking Area (Kusatsu P. A.) which is located between Ritto Interchange (Ritto I. C.) and W. Seta I. C. on the Meishin expressway. Concentrations of gaseous pollutants, were also measured in this 24 hours survey which was performed three times at 7 points simultaneously. The results obtained were as follows;
1) The total-traffic volume in this section was about 60000/day and the constitution ratios of large vehicles which had diesel engines were higher at night (6 p.m. to 4 a.m.) than in the day, the former ratio was 80 to 90% and the latter was 45 to 50%.
2) In the first survey, the concentration of SPM was about 250μg/m
3, a figure derived by the sum of the values in the fractional collection at the roadside. The size distribution curve of SPM showed two peaks; the first was in the fraction below 0.7μm and the second was at about 10μm. From the roardside to about 300m the SPM concentrations decreased with distance from the source of pollution, and the fraction below 0.5μm, which has a directly influence on human health, was above 70% in the particle size distribution at every point.
3) Daily average values of carbon monoxide (CO) and hydrocarbons (HC as methane) were in the range from 2.0 to 2.2ppm for CO and 5 to 6ppm for HC at the roadside.
4) Daily average values of nitrogen oxides (NOx) were in the range from 16 to 77ppb for nitrogen monoxide (NO), 19 to 37ppb for nitrogen dioxide (NO
2) and 39 to 120ppb for NOx at the roadside, while, the hourly values of NO
2 rose rapidly with the increase of traffic volume, 90 to 120ppb of NO
2 being measured from 10 to 12 a.m. when the traffic volume was at its maximum.
抄録全体を表示