Measurement of PM10, PM2.5 and TSP Particle Concentrations in Tehran, Iran
Ali Akbar Kakooei
Short-term exposure sampling of fine particle (PM2.5), coarse particle (PM10) and Total Suspended Particle (TSP) has been carried out at different located in Tehran, the capital of Iran. Samples were collected from summer, to winter of 2005, in North (N), South (S), West (W), East (E) and center of Tehran. The daily monitoring site was located 2 m above ground near highway and main streets. One hundred and seventeen simultaneous sampling of the airborne particle matter (MS) were collected using a direct-reading instrument, the TSI Inc. model 8520 Dusttrack aerosol monitor. The 24 h average PM10, PM2.5 and TSP concentrations during the sampling period were 122.1, 24.3 and 239.8 μg m3 respectively. Daily PM10 and TSP concentrations exceeded the National Ambient Air Quality Standard (NAAQS) of USA, for approximately 25.7 and 38.9% of the sampling days, respectively. Compared with NAAQS, the average PM2.5 measured concentration (24.3 μg m3) in Tehran was lower. The results also showed that for north of Tehran, the average particle matter concentrations (153.1 μg m3 for PM10, 32.4 μg m3 for PM2.5 and 269.6 μg m3 for TSP) were higher than other area. The average PM2.5/PM10 ratio for the five area were 0.19 compared to 0.15 to 0.25 reported by EPA. Three season monitoring data indicated that the average concentrations of PM10 in the winter (December to March), summer (Jun to July) and fall (November) were 116.4, 101.9 and 150.9 μg m3, respectively. PM2.5 levels in the seasons also were 10.9, 21.32 and 12 μg m3, respectively. These results clearly confirmed the non-parametric analysis (Kruskal-Wallis test) PM10 (p< 0.001), PM2.5 (p< 0.001) and TSP (p = 0.114).
Tehran with 7160097 population and a land area of 657 km2, is the
capital city of Iran and the center of Tehran province. The city is hemmed in
by the Alborz Mountains to the north, causing the increasing volume of pollutants
to become trapped, hovering over Tehran when the wind is not strong enough to
blow the pollution away. Tehrans high altitude, ranging between
3300 and 5000 feet, also makes fuel combustion inefficient, adding to the pollution
problem. Air pollution is the most serious of Iran' s environmental
problems, especially in Tehran due to the combination of two natural and man-made
factors. Research conducted in 1997 by the Tehran municipality involved the
cooperation of two international organizations: the World Bank and Japans
international cooperation agency. The research provided an exact picture of
the pollutant sources and their levels of responsibility for Tehrans notoriously
poor air quality. The results of this research indicated that the densities
of NO2 and SO2 in 1996 were below the standard limit determined
by EPA, but reached twice that ceiling in 2000. The index of air pollution (PSI)
also was reported as unhealthy for 252 days during 1999 and 282 days in 2002
(Anonymous, 1997). Thus, with regards to high volume of vehicular traffic and
the industrialized area Suspended Particulate Matter (SPM) is a main pollutant
and it may become a problem in cold seasons because of the topography of the
city and meteorological conditions (Peimaneh, 2000). In urban areas, particulate
air pollution is of particular interest for the possible delayed health effects
associated with the continues exposure of a high-density population (Marcazzan
et al., 2001; Harrison et al., 2001). High levels of Particulate
Matter (PM) such as TSP and PM10, have been reported during the period
of 22 December 2001 to 20 April 2002 in the ambient air a general hospital district
in Tehran (Kermani et al., 2003). Considering that 73% of air pollution
in Tehran is produced by vehicle emissions. In recent years, several projects
have been and are being, undertaken. Perhaps no other pollutants is as complex
as particle pollution. Also called Particulate Matter (PM) that consists of
a mixture of large materials, called coarse particles and smaller particles,
called fine particles. The impact of particulate air pollution on human health
has been known since the early 1950s (Lippman, 1989). Evidence from epidemiologic
studies have shown that ambient concentrations of airborne Particulate Matter
(PM) to increased respiratory and cardiovascular mortality and morbidity (USEAP,
2001; Katsouyanni et al., 1997; Norris et al., 1999; Schwaretz
and Dokery, 1992; Pope et al., 1995; Goldberg et al., 2001). This
implies an association between community exposure to PM of ambient origin and
adverse health effects. The Environmental Protection Agency (EPA) adopted, in
1997 both 24 h and annual average PM10 and PM2.5 standards,
on the basis that PM2.5 is the best currently available surrogate
hazard index for the health effects associated with ambient air PM (USEPA, 2001).
With the development of economy of Tehran in recent years, its particle pollution
has increasingly become sever to the emissions from traffic vehicles and paved
roods. Due to the particulate air pollution importance and its consequence especially
in large cities like Tehran, we have carried out daily PM10, PM2.5
and TSP sampling, from summer to winter of 2005, in the 5 area of Tehran. Furthermore,
in this study we gathering the data of meteorological variables from Islamic
Republic of Iran Meteorological Organization (IRIMO). Finally, we use non-parametric
analysis such us kruskal valis test and regression models to identify of particle
concentrations and distribution of Particulate Matter (PM) in the areas and
MATERIALS AND METHODS
Sampling and analysis: PM10, PM2.5 and TSP was conducted in the five area of Tehran at the 24 sampling site. These airborne particulate sampling station were located on the busy street and nearby the traffic highways. Sampling was done for winter, fall and summer. The Particulate Matter (PM) was collected in the sampling station at a height of about 2 m above ground. Twenty-four hour particulate matter sampling were collected daily from summer to winter of 2005. A total of 117 the PM valid samples were taken during the study. Two kinds of samplers have been used during the 24 h simultaneous sampling.
PM10 and PM2.5 measurements were collected using a direct reading instrument. The TSP sampling was carried out by gravimetric method on Whatman membrane filter of 25 mm with a pore size of 3.0 μm, using SKC sampling pump, which operated at a nominal flow rate of 0.00 to 10.000 L min-1 (Anonymous, 1996). The TSP was determined gravimetrically on pre-weighed and pre-conditioned filters conditioning consisted of an exposure of filters for 24 h at about 25°C constant humidity (around 50%). Before and after exposure, the filters were weighed using an analytical balance with a readied precision of ±10 μg. The direct reading instrument used in this study was TSI Inc. model 8520 Dusttrak aerosol monitor, which is a light scattering laser photometer with a laser diode directed at continuous aerosol stream. The Dusttrak was factory-calibrated to the repairable fraction of the International Organization for Standardization (ISO) 12103-1, A1 Arizona test dust (ISO, 1997).
Statistical analysis: Statistical analyses were performed using SPSS version 11.3. The relationships between the PM meteorological variables were investigated significance of the differences between distribution of PM and seasons and months were tested with the non-parametric kruskal-walis test. Regression analysis models also were used to identify determinates of particulate matter concentrations.
RESULTS AND DISCUSSION
Particulate matter concentrations: Non-parametric tests indicated that
the PM (PM10, PM2.5 and TSP), concentrations were log-normally
distributed (p<0.05). The concentrations of PM10 was ranged from
153.1 μg m3 at north to 81.8 μg m3 at east
of Tehran while that of PM2.5 was ranged from 32.4 μg m3 at north to 13.3 μg m3 at east. The TSP concentration was ranged
from 289.6 μg m3 at north to 173.7 μg m3 at
east. The ratio of coarse particles (greater than 2.5 μ) make up the majority
of aerosol (Table 1, 2). The annual arithmetic
mean PM10 concentration was 122.1 μg m3.
|| Summary of the PM loading at five area in Tehran
|N: North; S: South; E: East; W: West; C: Center; SD: Standard
|| Particle matter distribution according to seasons in Tehran
|SD: Standard Deviation; S: Significant; NS: Non-Significant;
PM: Particle Matter
This concentration is considerably higher than the NAAQS (1997) of 50 μg
m3 and the European Union air Quality annual PM10 standard
of 40 μg m3, respectively. The non-parametric analysis of krus-wallis
is indicated that distribution of PM10 in the seasons was significant
(p<0.011). PM2.5 concentrations also were log-normally distributed.
The mean concentrations of PM2.5 obtained for the locations was 24.3
μg m3, that very difference was found between the mean concentration
for the winter and summer, 19.6 and 38.5 μg m3, respectively.
Compared with the NAAQS of USA for particulate matter (65 μg m3
for PM2.5 over a 24 h period), the PM2.5 concentration
in Tehran were lower. The non-parametric test also indicated that distribution
of PM2.5 in the area of Tehran and the seasons were significant,
p<0.001, p<0.001, respectively. The mean concentration of TSP obtained
for the area of Tehran was 239.8 μg m3. TSP levels were found
to be 212.5 and 307.9 μg m3 in winter and summer, respectively.
Similarly to PM10 and PM2.5, distribution of TSP in the
5 area of Tehran was significant (p<0.001), but this distribution with regards
to seasonal or monthly was not significant (p<0.114). Compared with the NAAQS
of USA that know as the USEPA (2001), for total suspended particulates (260
μg m3 for TSP over a 24 h period), the TSP levels in Tehran
are clearly lower than the 24 h standards. But these high levels of TSP, especially
in winter (307.9 μg m3), may be due to high density of road
traffic in the Tehran.
Type of site: Previous studies indicated that particulate air pollution monitoring through a few fixed sites cannot give accurate exposure data of population (Han and Naeher, 2006; Kulkarni and Patil, 1999). Kulkarni and Patil (1999), studied the integrated exposure to respiratory particulate matter (PM2.5) among 24 outdoor workers in India and found that indicated by single monitoring site data. Similarly, in the netter lands, both PM10 and PM2.5 concentrations measured at a background site were 1.3 times lower than those observed near a busy road (Jansen et al., 1997).
Relationships between the PM concentrations: The monthly ratio of PM2.5/PM10
has little variability from 0.14 (February) to 0.3 (July). It indicates that
coarse particles (greater than 2.5 microns) make up the majority of aerosol
(Table 3). With regards to this results, the concentration
of coarse particle (PM10) in December was much higher than other
months. Based on the, meteorological condition of Tehran, December is very importantly
in inversion condition. In one study by USEPA (2001), the annual mean PM2.5/PM10
ratios measured in urban and semi-rural US areas were between 0.3 and 0.7.
|| Monthly the PM concentrations and PM2.5/PM10
ratio in Tehran
|All concentrations expressed in μg m3
to this study, low ratio of PM2.5/PM10 were observed in
the semi-area western US, where a large fraction of PM10 consists
of soil particles. Harrison et al. (2001) showed that PM2.5 comprises about
80% of PM10 during the winter month (July), the PM2.5/PM10
ratio was high. We also evaluated the relationships between PM10,
PM2.5 and TSP, respectively. During the study, the variations of
24 h simultaneous TSP and PM10 concentrations data were correlated
(R = 0.77) and this correlation had statistically significant at confidence
(p<0.001) (Fig. 1) The concentrations of PM10
were associated with PM2.5 concentrations, with correlation matter,
coefficient of 0.82. With regards to, levels of PM10 and TSP that
exceeded the standard level such as WHO standards (WHO, 2000), these high levels
of particle pollutant may be due to high density of road traffic in Tehran city.
Relationships between the PM and meteorological parameters: The relationships
between PM concentrations (PM10, PM2.5 and TSP) and wind
speed indicated that the particle matters were negatively correlated with wind
speed, R = -0.3, R = -0.01 and R = -0.06, respectively. As can be seen, the
relationships between the PM10 concentrations and wind speed is not
liner relationships (Fig. 2). In similar to this study, no
relationship between wind speed and TSP concentration was also found in Hong
Kong (Cheng and Lam, 1998). Investigators in Paris demonstrated lack of relationship
between PM2.5 concentrations measured near a highly trafficked road
and wind speed values (Ruellan and Cachier, 2001). We also analyzed the PM data
by the season and found significant differences between the periods (Table
2). As suggested by the results of the non-parametric test season is an
important determinant of both PM10 and PM2.5 and ratio
of PM2.5/PM10, with season significant p-value of p<0.011,
p<0.001 and p<0.001, respectively. The seasonal differences may be explained
by either the higher PM10 emissions during the colder season (December),
because this month having maximum inversion layers in Tehran. Similar observations
have been seen in Santiago, Chile (Kavouras et al., 2001). In present
study distribution of the PM (PM10 and PM2.5) appeared
in the kruskal-wallis test to be related to the months (Table
|| Correlation of PM2.5 and PM10 concentrations
|| Relationship between PM10 concentrations and wind
The significant differences between the PM concentrations and months were
found for PM10 (p<0.05), PM2.5 (p<0.001) and PM2.5/PM10
The determination for the particle matter of PM10, PM2.5 and TSP during the winter, fall and summer 2005, in Tehran was conducted. Air sampling were collected at five area of Tehran. Compared with the NAAQS of the USA and European Union Air Quality Standard for PM, particle pollution of PM10 and TSP in Tehran was higher. Especially for PM10, was more than two times the standards. The mean PM2.5 concentration was considerably lower than the US EPA 24 h period PM2.5 standard. With regards to results, TSP levels were found to be 239.8 μg m3 in the city areas. These high levels of pollutant may be due to high density of road traffic in the Tehran. It is important and we must keep in mind that particulate matter may have reached an alarming level considering many other streets with much higher traffic intensities than the street in which the fixed site was located. Prior studies also have suggested that air quality compliance measurements should be conducted at multiple monitoring sites within the city. In our study the average concentrations were based on measurements conducted at 24 sites located next to highly trafficked and frequently congested street. During the study the variation of 24 h simultaneous PM10 concentrations data with PM2.5 and TSP concentrations were correlated and these correlation had statistically significant. On the basis of the results when the relative humidity and temperature were in the range of 38-49% and 46-53°F, respectively, especially on fall season and more importantly in inversion conditions of Tehran, the highest concentration of PM10 would be expected (Table 2, 3). The our results are in agreement with the fact that particulate matter especially the PM10 concentration above the Tehran basin during low wind periods.
This study was support by Iranian Association of Environmental Health and Tehran University of Medical Sciences. Also we would to thank the IRIMO, which kindly provided the meteorological data.
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