Ambient particle concentration was taken on the traffic sampling site over
the Chung-Chi Road over the bridge (CCROB) in front of Hungkuang Institute
of Technology (HKIT). The sampling time was from August 1999 to December 19
99. During the sampling period, Taiwan's biggest earthquake in more than a
century registered 7.3 on the Richter scale (Taiwan Chi-Chi Earthquake). Be
sides, there are more than 20,000 aftershocks following the Taiwan Chi-Chi
Earthquake within 3 months. Thus, the mass concentration of particles with
aerodynamic diameters smaller than 2.5 mum (PM2.5) and PM2.5-10 was also co
llected then compared with the total mass concentration of suspended partic
les (TSP) in this study. The average TSP, PM2.5-10, and PM2.5; concentratio
ns are 106, 24.6, and 58.0 mug/m(3), respectively, after the Taiwan Chi-Chi
Earthquake. The average TSP concentrations before and after Taiwan Chi-Chi
Earthquake were 69.6 and 127 mug/ m(3), respectively. In addition, statist
ical analysis of the PM10 data from this study and EPA in 1999 yielded a T
statistic of 0.147, which is smaller than t((0.975.18)) = 2.101 It is indic
ated that there was no significant difference. So, the PM10 concentrations
measured after Taiwan Chi-Chi Earthquake in this study were also greater th
an those data previously obtained from Taiwan EPA in the same region of thi
s area. The relationships between TSP, PM10, PM2.(5-10), and PM2.5 particle
concentrations and wind speed (R-2) .77, .59, .58, .58, respectively. And
the ratios of PM2.5/PM2.5-10 PM2.5/PM10, and PM10/TSP are 221%, 67.2%, 58.0
%, respectively. The average ratios of PM2.5/PM2.5 to and PM2.5/PM10 increa
se by about 120% and 17%. It indicated that the fine-particles concentratio
n increases compared to the coarse-particles concentration after 921 Taiwan
Chi-Chi Earthquake. And the proposed reasons are that local motor vehicle
emissions combined the fine particles transported from the Chi-Chi epicente
r. More importantly, the wind direction was mainly blown from southeastern
part. These two main factors enhance the fine-particles concentration in th
is area. (C) 2001 Elsevier Science Ltd. All rights reserved.