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Roadside Particulate Air Pollution in Bangkok
Wanida Jinsart a , Kenji Tamura b , Samarnchai Loetkamonwit c , Sarawut Thepanondh d
Kanae Karita e & Eiji Yano e
,
a Department of General Science, Faculty of Science , Chulalongkorn University , Bangkok ,
Thailand
b National Institute for Environmental Studies , Tsukuba , Japan
c Environmental Science Program , Chulalongkorn University , Bangkok , Thailand
d Pollution Control Department , Ministry of Science, Technology, and Environment ,
Bangkok , Thailand
e Department of Hygiene and Public Health , Teikyo University School of Medicine , Tokyo ,
Japan
Published online: 27 Dec 2011.
To cite this article: Wanida Jinsart , Kenji Tamura , Samarnchai Loetkamonwit , Sarawut Thepanondh , Kanae Karita &
Eiji Yano (2002) Roadside Particulate Air Pollution in Bangkok, Journal of the Air & Waste Management Association, 52:9,
1102-1110, DOI: 10.1080/10473289.2002.10470845
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Jinsart et al.
TECHNICAL PAPER
ISSN 1047-3289 J. Air & Waste Manage. Assoc. 52:1102-1110
Copyright 2002 Air & Waste Management Association
Roadside Particulate Air Pollution in Bangkok
Wanida Jinsart
Department of General Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
Kenji Tamura
National Institute for Environmental Studies, Tsukuba, Japan
Samarnchai Loetkamonwit
Environmental Science Program, Chulalongkorn University, Bangkok, Thailand
Sarawut Thepanondh
Pollution Control Department, Ministry of Science, Technology, and Environment, Bangkok, Thailand
Kanae Karitaand Eiji Yano
Department of Hygiene and Public Health, Teikyo University School of Medicine, Tokyo, Japan
ABSTRACT
Roadside PM10 was measured simultaneously with the
Thailand Pollution Control Department (PCD) monitor-
ing station at the same site and at the intersections where
police work. The result from dual simultaneous measure-
ments of PM10 showed a good correlation (correlation
coefficient: r = 0.93); however, PM levels near the road-
side at the intersections were higher than the concentra-
tions at the monitoring station. The relationship between
ambient PM level and actual personal exposures was ex-
amined. Correlation coefficients between the general
ambient outdoors and personal exposure levels were 0.92
for both PM2.5 and PM10.
Airborne fine particles of PM2.5-10 and PM2.5 in Bangkok,
Nonthaburi, and Ayutthaya were measured from Decem-
ber 22, 1998, to March 26, 1999, and from November 30,
1999, to December 2, 1999. Almost all the PM10 values in
the high-polluted (H) area exceeded the Thailand National
Ambient Air Quality Standards (NAAQS) of 120 µg/m3.
The low-polluted (L) area showed low PM10 (34–74 µg/m3
in the daytime and 54–89 µg/m3 at night). PM2.5 in the H
area varied between 82 and 143 µg/m3 in the daytime
and between 45 and 146 µg/m3 at night. In the L area,
PM2.5 was quite low both day and night and varied be-
tween 24 and 54 µg/m3, lower than the U.S. Environmen-
tal Protection Agency (EPA) standard (65 µg/m3). The
personal exposure results showed a significantly higher
proportion of PM2.5 to PM10 in the H area than in the L
area (H = 0.80 0.08 and L = 0.65 0.04).
Bangkok air quality data for 1997–2000, including
24-hr average PM10, NO2, SO2, and O3 from eight PCD
monitoring stations, were analyzed and validated. The
annual arithmetic mean PM10 of the PCD data at the
roadside monitoring stations for the last 3 years de-
creased from 130 to 73 µg/m3, whereas the correspond-
ing levels at the general monitoring stations decreased
from 90 to 49 µg/m3. The proportion of days when the
level of the 24-hr average PM10 exceeded the NAAQS
was between 13 and 26% at roadside stations. PCD data
showed PM10 was well correlated with NO2 but not with
SO2, suggesting that automobile exhaust is the main
source of the particulate air pollution. The results ob-
tained from the simultaneous measurement of PM2.5 and
PM10 indicate the potential environmental health haz-
ard of fine particles. In conclusion, Bangkok traffic
police were exposed to high levels of automobile-
derived particulate air pollution.
IMPLICATIONS
The airborne particulates of PM10 and PM2.5 were mea-
sured at a busy intersection in Bangkok, and results indi-
cated almost all the values of PM10 exceeded the NAAQS
of 120 µg/m3. The PM2.5 to PM10 ratio was ~80%, sug-
gesting a high contribution of automobile exhaust. Road-
side PCD monitoring station data showed 24-hr average
PM10 exceeded the NAAQS on 13–26% of days per year.
These results suggest that Bangkok traffic police were
exposed to high levels of automobile-derived particulate.
Evaluation of the health effects of the particulate air pol-
lution is recommended.
1102 Journal of the Air & Waste Management Association
Volume 52 September 2002

Jinsart et al.
INTRODUCTION
areas and found the absolute PM exposures were under-
estimated by the ambient monitoring data. Because there
is increasing concern about the adverse health effects of
air pollution in Bangkok, our research team conducted
environmental and epidemiologic surveys to monitor the
level of fine PM and its relationship with lung diseases.
The prevalence of chronic respiratory symptoms and res-
piratory function was investigated in a group of traffic
police, a selected population considered to be at high risk
because of the roadside air pollution exposure during their
work. A significant association was found between par-
ticulate levels and respiratory impairment.25
In the present study, PM levels reported by the PCD
were assessed because of their continuity and wide cover-
age of the area monitored. In Bangkok and vicinity, 24-hr
average ambient air quality data of PM10, NO2, SO2, and
O3 were used in the selection of appropriate sampling sites.
For the present study of particulate monitoring, PM10 and
PM2.5 were collected simultaneously at various locations
in urban and rural areas of Bangkok. The ratio of PM2.5
and PM10 and the relationship between personal expo-
sure and PCD data were investigated to validate and in-
terpret actual human exposure concentrations.
There is an increasing recognition that the adverse health
effects from environmental exposure to airborne particu-
late matter (PM) are more significant than those from
exposure to gaseous pollutants. Throughout the last de-
cade, particularly in the United States but also in several
other countries, a growing number of epidemiologic stud-
ies have demonstrated the close relationship between daily
PM concentration and mortality and morbidity.1-6 Re-
cently, a number of reports on the adverse health effects
of PM in large cities have emerged. For example, Kunzli
et al.7 estimated the impact of outdoor and traffic-related
air pollution on public health in Austria, France, and Swit-
zerland, and traffic-related air pollution remains a key
target for public health action in Europe. Schwartz8 ex-
amined daily deaths and hospital admissions in Chicago
for 1988–1993 and found that PM less than 10 µm in
aerodynamic diameter (PM10) was associated with in-
creased daily deaths and hospital admissions. Fine par-
ticulate measurement and source apportionment have
been studied throughout the world, including in Austra-
lia,9 Chile,10 Mexico,11 and central Europe.12
The proportion of smaller particles is especially im-
portant in the estimation of health risk. PM2.5 (PM with
an aerodynamic diameter of less than 2.5 µm), in particu-
lar, has been shown to be more strongly related to ad-
verse health effects. The hazardous characteristics of PM2.5
are caused by its deeper penetration and consequent
greater deposition in the lung, as well as its higher con-
centration of toxic substances.13,14 In the United States,
regular measurement of PM2.5 has been initiated, and the
PM2.5 standard was introduced in 1997.15,16 In Thailand,
PM2.5 has not been investigated extensively, and the Thai-
land Pollution Control Department (PCD) is in the pro-
cess of establishing National Ambient Air Quality
Standards (NAAQS) for PM2.5.17
Although there have been several studies on personal
exposure of gaseous pollutants, few have been reported
on PM.24-26 PM exposure measurement requires active sam-
pling with a pump; therefore, it is not convenient to use
in practice. For a more comprehensive evaluation of the
health effects of PM, measuring PM10 was considered to
be insufficient, and thus, in the present study, personal
samplers for the simultaneous measurement of PM2.5 and
PM10 also have been used.
METHODS
Comparison of PM10 Measurement Techniques
To compare the level of PM10 measured by the β-ray attenu-
ation method at the PCD monitoring station with that
obtained simultaneously by the personal sampler, a per-
sonal air sampler was installed at the rooftop air inlet of
the Dindaeng roadside monitoring station. Six 12-hr aero-
sol collections were performed and compared to the hourly
PCD data from the identical time period. The sampling
filters then were quantified by the gravimetric method.
Bangkok, with a population of more than 6 million,
has long faced serious air pollution problems. Several re-
ports have indicated that the major source of air pollut-
ant in Bangkok is PM emitted from vehicles.18-20 In many
of its congested streets, the levels of total suspended par-
ticulates (TSP) and PM10 were higher than the NAAQS (24-
hr average concentration of TSP = 330 µg/m3 and PM10
=
120 µg/m3 ).21 Ostro et al.22 studied the impact of PM on
daily mortality in Bangkok from 1992 to 1995. They indi-
cated a statistically significant association between daily
PM10 and daily mortality.22 Nouchpramool et al.23 reported
on the airborne particulate characterization by neutron ac-
tivation analysis. This study was conducted from January
1997 to May 1998. The collecting site was in the suburban
area of Bangkok, and the fine particulate level was very
low (average PM2.5 = 4.6 µg/m3). Tsai et al.24 studied the
indoor and outdoor particulate level in the busy shopping
PM10 and PM2.5 in Bangkok
Selection of Sampling Sites. For PM measurement, high-
polluted (H) sites from several busy intersections of ma-
jor 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 crite-
ria in the site selection. In the metropolitan area, three
busy intersections, Dindaeng, Ramkhamhaeng (both PCD
Volume 52 September 2002
Journal of the Air & Waste Management Association 1103

Jinsart et al.
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 vol-
umes averaging less than 40,000 vehicles per day, and were
more than 30 km from inner Bangkok.30 Figure 1 illus-
trates 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 low-
polluted 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 cas-
cade 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 particu-
late sampling. Before sampling, poly(tetrafluoroethylene)
binding glass fiber filters (Pallflex T60A20) were equili-
brated 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
Figure 1. Map showing Bangkok and the sampling sites in the H, M, and L areas: ❑ Between site 1 and 2 represented the location of Victory
Monument, marking the position of inner Bangkok in this study.
1104 Journal of the Air & Waste Management Association
Volume 52 September 2002

Jinsart et al.
Table 1. Sampling period and number of samples at locality sites.
Outside Booth
number of days on which
the levels exceeded the
NAAQS of Thailand for
PM10 and its chronologi-
cal change from PCD data
also were counted. In ad-
dition, correlation coeffi-
cients between particle
and gaseous air pollutant
levels measured at the
PCD monitoring stations
between April 1997 and
March 2000 were calcu-
lated to help identify the
possible source of PM.
Inside Booth
Day
Personal
Day
PCD Station
Area/Site
Sampling Period
Day
Night
Day
Night
Bangkok (H)
Dindaeng
Dec 22–25, 1998
Feb 15–18, 1999
Feb 23–26, 1999
March 16–19, 1999
6
3
3
6
3
3
5
3
3
5
3
3
6
–
–
6
–
–
Pathumwan
Ramkhamhaeng
Nonthaburi (M)
Ngarm Wongwan
Bangkok (L)
Talad-Ku
Dec 22–25, 1998
3
3
3
2
–
–
Nov 29–Dec 2, 1999
Nov 30–Dec 2, 1999
March 24–27, 1999
2a
2a
3
3a
2a
3
–
–
–
1
2
2
–
–
3
–
–
2
Prachasumran
Ayutthaya
aOutdoor sampling at Talad-Ku and Prachasumran were performed with two samplers simultaneously.
conditions, and the particulate mass was measured by the
gravimetric method using an electric ultramicrobalance
(Mettler UM3) with a sensitivity of 0.1 µg. PM10 concen-
tration is the sum of the PM2.5 concentration calculated
from the increase in weight of the backup filter and the
PM2.5-10 concentration calculated from the gain of the 2-µm
impactor filter.
RESULTS
Parallel Measurement of PM10
Means of CV among air samplers for PM2.5, PM2.5-10, and
PM10 were 5.1, 5.3, and 2.9%, respectively, indicating high
precision of the air samplers. The comparison between
PCD data for PM10 and our measurement during the same
period at the inlet of the particulate monitor installed on
top of the PCD station is shown in Figure 2. Although
PCD data and PM10 values were well correlated (r = 0.93;
n = 6), the slope of the regression line was 1.54, indicat-
ing a higher value than the PCD report from direct read-
ing of β-ray attenuation. The correlation between PCD
data and PM2.5 values measured by our method was even
higher (r = 0.94), and the slope was 1.07.
The precision test of the personal air sampler was per-
formed by placing two personal air samplers close together
and sampling at the same flow rate at the low-pollution
sites—Prachasumran and Talad-Ku—nine times (see
Table 1). All the air samplers were calibrated by the same
flow meter. The filter holders were randomly selected from
a large stock, and the precision was evaluated by coeffi-
cient of variation (CV).
Sampling Procedure. The particulate samplings were con-
ducted at road intersections both inside and outside the
police booth for 12 hr each during the day (approximately
6:00 a.m.–6:00 p.m.) and at night on weekdays. The per-
sonal exposure and intersection measurements were per-
formed simultaneously from approximately 6:00 a.m. to
6:00 p.m., and when an officer completed his shift in the
daytime, the same personal sampler was taken to the of-
ficer on the next shift. Normally, police stand in the cen-
ter of the intersection when traffic is busy and stay in the
police booth while resting. The time period for sampling
and the number of samples collected at each site are shown
in Table 1.
Air Pollution Monitoring in Bangkok
There were 28 PCD monitoring stations in Bangkok, two
stations in Nonthaburi, and one station in Ayutthaya. Air
quality data available since 1997 from eight PCD stations
were used in this study. The PM10 data of the PCD were
evaluated by comparing them with our parallel measure-
ment conducted by the method described previously. The
Figure 2. Correlation of PM10 and PM2.5 by the personal sampler and
PM10 by the β-ray attenuation method by the PCD at the Dindaeng
monitoring station.
Volume 52 September 2002
Journal of the Air & Waste Management Association 1105

Jinsart et al.
Table 2. Average concentration of particle size samples at locality sites.
Daytime Concentration
(µg/m3)
Nighttime Concentration
(µg/m3)
Outside Booth
Inside Booth
Personal
Outside Booth
PM2.5 PM2.5-10 PM2.5
/
PM2.5 PM2.5-10 PM2.5
/
PM2.5 PM2.5-10 PM2.5
/
PM2.5 PM2.5-10 PM2.5/
Site
PM10
PM10
PM10
PM10
H
Dindaeng
143
108
82
57
39
36
48
10
14
28
0.71
0.74
0.70
0.67
0.70
0.68
0.62
144
144
81
74
–
21
16
9
0.87
0.90
0.89
0.82
–
166
109
102
113
23
28
28
43
42
12
13
27
0.86
0.80
0.77
0.73
0.65
0.72
0.62
146
45
69
34
38
62
21
22
35
0.68
0.57
0.65
0.64
0.62
0.61
0.60
Pathumwan
Ramkhamhaeng
Ngarm Wongwan
Prachasumran
Talad-Ku
71
M
L
95
16
–
107
34
24
29
–
–
–
34
36
Ayutthaya
47
–
–
–
44
54
Note: PM10 concentration is the sum of the PM2.5 concentration and the PM2.5-10 concentration. Values of concentration and proportion were the means of plural samplings.
PM10 and PM2.5
exposure level of police to PM was roughly the same as
the atmospheric PM level measured at the intersection.
The PM level in the police booth did not differ much
from the corresponding outdoor level, except at
Pathumwan. Despite the large difference in the atmos-
pheric level of PM10 between the H and L areas, the pro-
portion of PM2.5 to PM10 indicated roughly the same value
of 0.7 in both areas. In contrast, the results of personal
exposure showed a significantly higher proportion of
PM2.5 to PM10 in the H area than in the L area (H: 0.80
0.08 vs. L: 0.65 0.04). Closer examination of the varia-
tion throughout the day revealed that the proportion of
PM2.5 to PM10 in the daytime was slightly larger than that
at night.
Detailed results of the measurement are shown in Table 2.
Almost all the values of PM10 in the H area exceeded the
NAAQS, except in Pathumwan at night. The L area at
Prachasumran and Talad-Ku, as well as Ayutthaya,
showed low PM10 (34–74 µg/m3 in the daytime and 54–
89 µg/m3 in the nighttime). PM2.5 in the H area varied
between 82 and 143 µg/m3 in the daytime and between
45 and 146 µg/m3 at night. In the L area, PM2.5 varied
between 24 and 47 µg/m3 in the daytime and between
34 and 54 µg/m3 at night.
The ratio of PM2.5-10 to PM2.5 in outdoor air was 0.35
in the H area and 0.40 in the L area; that is, the propor-
tions of PM2.5 to PM10 were 0.74 and 0.72, respectively,
and the correlation coefficient of PM2.5-10 and PM10 was
0.898 in the H area and 0.650 in the L area. The personal
Figure 3 indicates the correlation between atmos-
pheric measurements from our sampler equipped with the
Figure 3. Correlation between the measurement at the monitoring station and outside the police booth for PM2.5 and PM10 in Dindaeng, Bangkok.
1106 Journal of the Air & Waste Management Association
Volume 52 September 2002

Jinsart et al.
PM2.5 and PM10 cascade, placed in the center of the
Dindaeng intersection, with that on the top of the
Dindaeng PCD monitoring station, which was located at
the roadside 300 m from the intersection. PM10 and PM2.5
datawere closely correlated at the two simultaneous mea-
surement sites. Correlation coefficients were 0.80 for PM2.5
and 0.88 for PM10. The slope of the regression line was
0.50 with an intercept of 113 µg/m3, suggesting higher
PM levels at the intersection site.
Figure 4 shows the correlation between PM2.5 and
PM10 measured outside the booth and personal exposure.
There was a good correlation between personal exposure
and the ambient air outside the police booth for both
PM2.5 and PM10. There was a better association than the
correlation in Figure 3 because the sampling sites were
in the same areas as the personal exposure measurements.
The correlation coefficients of both PM2.5 and PM10 in-
creased to 0.92.
for the general area at Ramkhamhaeng, the data varied
between 53 and 62 µg/m3. In 1997, the annual average
PM10 exceeded 100 µg/m3 at the two roadside stations but
decreased to 80 µg/m3 in 1999. The decreasing tendency
also was observed in the general area monitoring stations.
The proportion of days when the level of 24-hr average
PM10 exceeded the NAAQS of 120 µg/m3 in 1997–2000 were
reduced annually, as shown in Table 3. In the three road-
side stations, the average percentage of the days on which
the PM10 level was found to be higher than the NAAQS
decreased from 27 to 11%, and in the five general area
monitoring stations, the equivalent data decreased from
9 to 3%. The relationship between PM10 and NO2 or SO2
for the last 3 years, both in the roadside and general area
stations, is illustrated in Table 4. While the correlation
coefficients between PM10 and SO2 were small, PM10 and
NO2 were high at all eight stations.
DISCUSSION
PM Level in Bangkok
The results of the direct measurement for PM10 by the
personal samplers at the PCD station in Dindaeng were
1.5 times higher than that by the PCD with the β-ray
attenuation method. In this study, data from eight moni-
toring stations in Table 2 were used as information for
site selection. These continuous data also reflected the
trend of PM levels.19 It is not a simple matter to decide
whether PCD measurements or those by personal sam-
plers are more valid, but it is worthy to note that closer
comparative results were obtained between PCD data and
PM2.5 values, with a slope of 1.07. The fact that PM2.5 has
been demonstrated as a factor directly related to hazard-
ous health effects provides support for the use of PCD
data in the epidemiologic study of particulate air pollu-
tion. In Thailand, the NAAQS for the 24-hr average PM10
The data of eight PCD monitoring stations in the metro-
politan area were accessed from the Web site http://
www.pcd.go.th/AirQuality/bangkok/. The high-volume air
sampling method was specified in the Thai Air Quality
Standard for PM10, but in the case of online data, it was
conducted by β-ray attenuation, which was standardized
against the conventional method. In this study, data from
eight monitoring stations (Table 3) were used for site se-
lection. These continuous data also reflected the trend of
PM levels.2 Among them, Dindaeng and Ramkhamhaeng
were selected as sampling sites. As can be seen in Table 4,
PCD data of the annual arithmetic average PM10 concen-
tration at the Dindaeng roadside monitoring station for
the last 3 years varied between 73 and 130 µg/m3, whereas
Figure 4. Correlation between outside the booth and personal exposure for PM2.5 and PM10 measured simultaneously using the same samplers.
Volume 52 September 2002
Journal of the Air & Waste Management Association 1107

Jinsart et al.
Table 3. Average daily concentration of PM10 (µg/m2) at PCD monitoring stations in Bangkok.
April 1997–March 1998
April 1998–March 1999
April 1999–March 2000
% of days 120
% of days 120
µg/m3 a
% of days 120
Site
Mean SD
µg/m3 a
Mean SD
Mean SD
µg/m3 a
Roadside
General
Dindaeng
130.3 43.4
84.1 27.1
103.5 31.2
106.0
44.6
11.6
25.8
27.3
15.5
4.1
96.1 34.3
98.5 35.7
74.5 21.4
89.7
23.5
22.8
4.2
73.6 26.4
89.6 31.8
78.5 27.7
80.6
6.7
15.7
9.2
Intrapituk
Lad Phrao
Average
16.8
11.6
2.8
10.5
3.2
Bang Khunthien
Ramkhamhaeng
National Housing
Authority (NHA)
Huai Khwang
Yannawa
82.4 39.0
62.2 24.9
70.0 32.1
52.9 21.7
57.3 26.4
57.4 24.1
1.4
61.6 23.4
90.1 30.9
71.3 24.4
73.5
2.7
15.0
5.6
58.5 25.1
81.9 29.0
65.9 25.8
65.8
2.1
12.3
3.8
49.0 21.5
73.6 24.0
62.5 22.7
60.0
1.2
5.3
2.6
2.7
Average
8.6
6.5
a120 µg/m3 is the Thai National Standard for PM10.
is 120 µg/m3, and the annual average (arithmetic mean)
is 50 µg/m3.21 Analysis of the data between 1997 and 1999
indicates the average 24-hr PM10 level in Bangkok moni-
tored at the roadside stations exceeded the Thai standard
on more than 10% of days, and in most of the stations,
the annual level of PM10 exceeded the NAAQS. Although
there are high-volume air samplers (the method required
by the NAAQS) at some PCD stations, because of the lower
value obtained from the b-ray attenuation data compared
with our active pump sampling measurement, the PM
exposure of traffic police assessed by PCD data may be an
underestimate for personal exposure concentrations.
Therefore, this is the first report to show the actual fine
particulate exposure in the high-risk group.
Averaging the concentrations across all sites indicated
~70% of the PM10 were fine particles (PM2.5). However,
there is a considerable variability in daytime and night-
time ratios, in addition to the variation between individual
measurements. The ratio of fine mass to coarse mass in
outdoor air in the H area was slightly higher than that in
the L area (see Table 3), and the correlation coefficient of
PM2.5 and PM2.5-10 was higher in the H area than in the L
area. This reflected that the fine particles in the H area of
Bangkok are from automobiles rather than from soil dust.
The correlation between fine and coarse particles is greater
in the H area than in the M and L areas. The study of the
contribution of PM2.5 to PM10 should be developed fur-
ther, and more parallel measurements could help to esti-
mate PM2.5 levels from the existing PM10 data. The study
of police exposure to PM10 indicated good agreement be-
tween personal monitoring data and ambient level at the
intersections. However, the personal exposure level of
PM2.5 was higher than the atmospheric level. Likewise,
there was a good correlation between the PM concentra-
tion measured by the sampler and data from the PCD;
however, the absolute level between the two measure-
ments showed a significant difference.
Although air quality PCD reports indicate that
Bangkok’s air pollution has improved somewhat in recent
years,19,20 the results of the present study imply that the level
remains unsatisfactory and show that further efforts are re-
quired to reduce pollution and monitor adverse health ef-
fects. The more hazardous portion of fine particles, namely,
PM2.5, has come into prominence only recently, and no Asian
country, including Thailand, has yet started routine moni-
toring or set the standard for PM2.5. In this study, the EPA
provisional standard was used as the basis for our discus-
sion, namely, a PM2.5 24-hr average of 65 µg/m3 and PM2.5
annual average of 15 µg/m3.15 The number of sites and days
of measurement were limited. However, the level of PM2.5 at
the intersections of Bangkok in the H area was between 82
and 143 µg/m3, far exceeding the U.S. standard, while the
TSP and PM10 levels were within the standard. Thus, despite
the latter findings, the control effort should be continued to
reduce health risks because PM2.5 was relatively high. This
suggests the necessity of air pollution control regardless of
the standard based on either PM2.5 or PM10.
Because the monitoring data were not available at
exactly the same time as our personal measurement for
PM exposure, the ambient particulate level at the road-
side could not be compared directly with personal expo-
sure. Further investigation on the differences between
monitoring sites and the atmospheric environment at
the intersections should be considered, such as the dis-
tance from monitoring stations to the emission areas,
other possible particulate sources, and related meteoro-
logical conditions. It is also important, because of the
large variation of the level of air pollutants throughout
1108 Journal of the Air & Waste Management Association
Volume 52 September 2002

Jinsart et al.
Table 4. Relationship between the level of particulate and gaseous air pollutants at roadside and general area PCD monitoring stations in Bangkok between April 1997 and March 2000.
April 1, 1997–
April 1, 1998–
April 1, 1999–
1997–
2000
Rb
March 31, 1998
March 31, 1999
March 31, 2000
a
a
a
a
a
a
PM10 and NO2
PM10
NO2
Rb
PM10
NO2
Rb
PM10
NO2
Rb
Roadside
Dindaeng
Intrapituk
130.3
84.1
97.4
46.8
33.4
28.2
0.874
0.822
0.535
96.1
98.5
74.5
41.7
32.0
22.4
0.756
0.851
0.366
73.6
89.6
78.5
49.3
33.4
30.5
0.874
0.706
0.762
0.676
0.778
0.572
Lad Phrao
General
Ramkhamhaeng
Bang Khunthien
NHA
62.2
82.4
61.6
90.1
71.3
20.7
17.7
21.7
32.9
21.7
0.787
0.889
0.754
0.703
0.738
52.9
70.0
58.5
81.9
65.9
18.6
15.4
20.2
31.6
18.4
0.653
0.848
0.835
0.757
0.715
57.4
57.3
49.0
73.6
62.5
22.9
24.2
17.0
35.9
28.8
0.871
0.865
0.767
0.632
0.572
0.790
0.722
0.798
0.668
0.656
Huai Khwang
Yannawa
April 1, 1997–
April 1, 1998–
April 1, 1999–
1997–
2000
Rb
March 31, 1998
March 31, 1999
March 31, 2000
a
a
a
a
a
a
PM10 and SO2
PM10
SO2
Rb
PM10
SO2
Rb
PM10
SO2
Rb
Roadside
Dindaeng
Intrapituk
130.3
84.1
97.4
14.6
8.6
0.544
0.524
0.265
96.1
98.5
74.5
13.9
7.9
0.530
0.383
0.124
73.6
89.6
78.5
13.2
6.9
0.305
0.032
0.173
0.465
0.309
0.073
Lad Phrao
General
11.7
5.4
9.3
Ramkhamhaeng
Bang Khunthien
NHA
62.2
82.4
61.6
90.1
71.3
9.2
7.8
0.220
0.439
0.163
0.003
0.193
52.9
70.0
58.5
81.9
65.9
7.8
7.5
0.086
0.284
0.047
0.088
0.079
57.4
57.3
49.0
73.6
62.5
6.6
9.5
0.094
0.232
0.027
0.025
0.027
0.148
0.260
0.105
0.080
0.124
8.0
7.2
6.4
Huai Khwang
Yannawa
11.7
24.5
9.2
7.2
22.1
18.5
Note: Italic amounts indicate p > 0.01; aYearly average of PM10 (µg/m3), NO2 (ppb), and SO2 (ppb) in each PCD station; bR is the correlation coefficient for the 24-hr average
concentrations between PM10 and NO2 or SO2.
the day, to use a measuring method with a sufficient
time-resolution function. In the meantime, it may be
reasonable to estimate personal exposure level at the
roadside using existing data. As shown in Table 4, PM10
was well correlated with NO2 but not with SO2, suggest-
ing automobile exhaust as the major source of the air-
borne particles. Further analysis to differentiate the
health effects of PM10 from those of NO2 may not be
possible; however, we would like to emphasize the ur-
gent necessity to monitor health effects of automobile
air pollution on highly exposed groups such as traffic
police. We believe the findings of the present study are
of benefit to improve air pollution control in Thailand,
both in monitoring particle levels and in further research
into the deleterious health effects of PM.
PCD data, they were well correlated. The higher ratio of
coarse mass to fine mass in outdoor air and the higher
correlation coefficient of PM2.5 and PM2.5-10 in the H area
reflected the automobile sources. The personal exposure
level of police to PM was roughly the same as the atmo-
spheric PM level measured at the intersection, and the
exposure showed a significantly higher proportion of PM2.5
to PM10 in the H area than in the L area. The annual PM10
level at the roadside from the PCD monitoring data con-
firmed the high particulate air pollution found by our
measurement and that automobile exhaust was the main
source of the particulate air pollution.
For future study, we also would emphasize the ur-
gent necessity to monitor the health effects of air pollu-
tion in highly exposed groups, namely, traffic police, bus
drivers, and motorcycle messengers. Although a standard
method for monitoring air pollution has been imple-
mented, little information on the relationship between
exposure and chronic health effects has been available.
The existing monitoring procedures and standards may
CONCLUSIONS
Almost all the values of PM10 at the high-polluted sites (H
area) in Bangkok exceeded the NAAQS. Although PM10
concentration measured by our sampler was 1.5 times the
Volume 52 September 2002
Journal of the Air & Waste Management Association 1109

Jinsart et al.
17. Wangwongwatana, S. Ambient Air Quality Monitoring Network in
Thailand. Presented at the Clean Air Regional Workshop, Fighting
Urban Air Pollution: From Plan to Action, February 12–14, 2001; Pa-
per No. 26.
need to be revised to include specific measurement of the
fine particles as PM2.5.
18. Radian International LLC. PM Abatement Strategy for the Bangkok Met-
ropolitan Area: Final Report; Pollution Control Department, Ministry
of Science, Technology and Environment: Bangkok, Thailand, Sep-
tember 1998; pp 2-36–2-52.
19. Pollution Control Department Annual Report, Situation and Management
of Air and Noise Pollution in Thailand; Pollution Control Department,
Ministry of Science, Technology and Environment: Bangkok, Thai-
land, 1998; pp 16-45.
20. Pollution Control Department Annual Report, Situation and Management
of Air and Noise Pollution in Thailand; Pollution Control Department,
Ministry of Science, Technology and Environment: Bangkok, Thai-
land, 1999; pp 6-17.
21. Notification of the National Environment Board, No. 10 (1992) un-
der the Enhancement of National Environmental Quality Act B.E.
2535 (1992); Royal Government Gazette, May 25, 1995, No. 1, Part 52,
B.E. 2538.
ACKNOWLEDGMENTS
This study was funded by a grant-in-aid from the Minis-
try of Education, Science, Sports and Culture (Monbusho),
Japan, 1998–1999. Partial funding was received from
the Thailand-Japan Technology Transfer Project.
Chulalongkorn University supported the field visit of col-
laborators from Japan in November 1999. The authors
thank the Thailand Pollution Control Department for
providing the ambient air particulate monitoring data to
compare with our study. In particular, we would like to
acknowledge the assistance of the traffic police at the stud-
ied sites for their patience and support in carrying the
personal pump required for roadside monitoring.
22. Ostro, B.; Chestnut, L.; Vichit-Vadakan, N.; Laixuthai, A. The Impact
of Particulate Matter on Daily Mortality in Bangkok, Thailand; J. Air
& Waste Manage. Assoc. 1999, 49, 100-107.
23. Nouchpramool, S.; Sumitra, T.; Leenanuphunt, V. Characterization
of Airborne Particulates in Bangkok Urban Area by Neutron Activa-
tion Analysis; Biol. Trace Elem. Res. 1999, 71-72, 181-187.
24. Tsai, F.C.; Smith, K.R.; Vichit-Vadakan, N.; Ostro, B.D.; Chestnut, L.G.;
Kungskulniti, N. Indoor/Outdoor PM10 and PM2.5 in Bangkok, Thai-
land; J. Expos. Anal. Environ. Epidemiol. 2000, 10 (1), 15-26.
25. Karita, K.; Yano, E.; Jinsart, W.; Boudoung, D.; Tamura, K. Respiratory
Symptoms and Pulmonary Function among Traffic Policemen in
Bangkok; Arch. Environ. Health 2000, 56 (5), 467-470.
26. Tamura, K.; Ando, M.; Sagai, M.; Matsumoto, Y. Estimation of Level
of Personal Exposure to Suspended Particulate Matter and Nitrogen
Dioxide in Tokyo; Environ. Sci. 1996, 4 (1), 37-51.
27. Rojas-Bracho, L.; Suh, H.H.; Koutrakis, P. Relationships among Per-
sonal, Indoor, and Outdoor Fine and Coarse Particle Concentrations
for Individuals with COPD; J. Expos. Anal. Environ. Epidemiol. 2000,
10, 294-306.
28. Janssen, N.A.H.; Hoek, G.; Harssema, H.; Brunekreef, B. Personal Ex-
posure to Fine Particles in Children Correlate Closely with Ambient
Fine Particles; Arch. Environ. Health 1999, 54 (2), 95-101.
29. National Research Council, Committee on Research Priorities for Air-
borne Particulate Matter. Research Priorities for Airborne Particulate
Matter; National Academy Press: Washington, DC, 1999.
30. Annual Report, Office of the Commission for the Management of Road
Traffic: Bangkok, Thailand, 1999.
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About the Authors
Wanida Jinsart (corresponsing author; e-mail: jwanida@
chula.ac.th) is an associate professor in the Department of
General Science, Faculty of Science, Chulalongkorn Uni-
versity, Bangkok, Thailand. Kenji Tamura is at the National
Institute for Environmental Studies, Environmental Health
Sciences Division, Epidemiology and International
Health Research Section, Onogawa, Japan. Samarnchai
Loetkamonwit is in the Environmental Science Program of
the Graduate School at Chulalongkorn University, Bangkok,
Thailand. Sarawut Thepanondh is in the Pollution Control
Department, Air and Noise Quality Management Division,
Ministry of Science, Technology and Environment, Bangkok,
Thailand. Kanae Karita is in the Department of Hygiene and
Public Health, Teikyo University School of Medicine, Tokyo,
Japan. Eiji Yano is department head of the Department of
Hygiene and Public Health, Teikyo University School of
Medicine, Tokyo, Japan.
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16. Kleeman, J.M.; Cass, R.J. Effect of Emissions Control Strategies on
the Size and Composition Distribution of Urban Particulate Air Pol-
lution; Environ. Sci. Technol. 1999, 33, 177-189.
1110 Journal of the Air & Waste Management Association
Volume 52 September 2002