PM10 and PM2.5 in Bangkok
Selection of Sampling Sites. For PM measurement, highpolluted
(H) sites from several busy intersections of major
roads in Bangkok and low-polluted (L) sites from several
suburban areas were selected. The background air quality
data, traffic volume information, and distance from the
Victory Monument at inner Bangkok were used as criteria
in the site selection. In the metropolitan area, three
busy intersections, Dindaeng, Ramkhamhaeng (both PCD
Downloaded by [182.53.120.235] at 07:19 03 September 2014 Jinsart et al.
1104 Journal of the Air & Waste Management Association Volume 52 September 2002
monitoring station sites), and Pathumwan (business and
trading site), were selected as H sites. Traffic volumes at
these intersections, which are less than 5 km from inner
Bangkok, averaged more than 70,000 vehicles per day.
The Ngarm Wongwan intersection in Nonthaburi (close
to the northwest suburb of Bangkok) was selected as the
moderate-polluted (M) site, and it is 10 km from inner
Bangkok. The L sites in the northeast suburb of Bangkok
were Prachasumran and Talad-Ku, which had traffic volumes
averaging less than 40,000 vehicles per day, and were
more than 30 km from inner Bangkok.30 Figure 1 illustrates
Bangkok and vicinity and the sampling sites used
in this study. Ayutthaya (98 km north from Bangkok) was selected as a background site representing the very lowpolluted
rural area. Details of the studied sites are
summarized in Table 1.
Personal Air Sampler. Single-nozzle personal air samplers
(Sibata Scientific Technology, Ltd.) equipped with two cascade
impactors with 50% cut-off level of 10 and 2.5 µm at
a flow rate of 2.5 L/min were used for size-selected particulate
sampling. Before sampling, poly(tetrafluoroethylene)
binding glass fiber filters (Pallflex T60A20) were equilibrated
for 24 hr at a temperature of 25 ºC and relative
humidity of 50% and then weighed. After the sampling
process, filters were equilibrated again under the same