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Atmospheric Environment 39 (2005) 2323–2338

www.elsevier.com/locate/atmosenv

Analysis of impacts on urban air quality by restricting theoperation of passenger vehicles during Asian Game events

in Busan, Korea

Byeong-Kyu Leea,�, Na-Young Juna, Haengah Kim Leeb,c

aDepartment of Civil and Environmental Engineering, University of Ulsan, Ulsan 680-749, Republic of KoreabEnvironmental Studies Ph.D. Program, University of Massachusetts, Lowell, MA 01854, USA

cUlsan Environmental Management, Ulsan Development Institute, Buk-gu, Yeonam-dong, Ulsan 683-804, Korea

Received 26 July 2004; accepted 19 November 2004

Abstract

This study is an analysis of the impacts on urban air quality of restricting the operation of passenger vehicles during

the 24th Asian Games (AG). Passenger vehicles in Busan were not allowed to operate on the alternative days during the

AG period. This restricted operation of passenger vehicles was enforced to improve an urban air quality in Busan

during the AG period. The average usage rate of passenger vehicles under an alternate (or restricted) operation was

95.4% and thus the average traffic flow rate (vehicle operation speed) increased approximately 28.1% as compared to

normal periods. We analyzed the ambient concentrations of criteria air pollutants measured at 13 air-monitoring

stations in Busan (Pusan), Korea, for the three periods of ‘‘before (13–28 September 2002)’’, ‘‘during (29 September–14

October 2002)’’ and ‘‘after (15–30 October 2002)’’ the AG. The 1-h, 24-h and 16-day averages or median concentrations

of each classified term were compared to those of other terms. The median concentrations, based on 24-h average data

of each day, of PM10, CO, NO2, and SO2 in the ambient during the alternate operation period of 16 days substantially

increased as compared to the terms before or after. However, the median concentration of O3 during the AG period was

slightly less than that of the term before. The ambient O3 concentrations during daytime (12:00–19:00) under alternate

operation substantially increased as compared to the terms before or after. However, the ambient O3 concentrations

during nighttime (22:00–07:00) under alternate operation decreased when compared to the terms before or after. For

the alternate operation period of passenger vehicles, the average concentrations of PM10, NO2, SO2, and daytime O3

measured at the air-monitoring stations near the stadiums were much higher than those of the other areas excluding the

stadium areas. However, average CO concentrations at the other areas were higher than those nearby the stadiums

during the alternate operation period.

r 2005 Elsevier Ltd. All rights reserved.

Keywords: Asian Game; Vehicle emission; Alternate operation; Air pollution; Monitoring

e front matter r 2005 Elsevier Ltd. All rights reserve

mosenv.2004.11.044

ing author. Tel.: +8252 259 2864;

2629.

ess: bklee@ulsan.ac.kr (B.-K. Lee).

1. Introduction

The Asian Games (AG) are one of the biggest

international sporting events, held in Asia, similar to

the Olympic Games. National or local governments that

d.

ARTICLE IN PRESSB.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–23382324

hold the Olympic Games, the Football World Cup or

the AG try to keep their environment clean through a

variety of activities, such as reducing air emissions from

stationary or mobile sources (EMC, 2002; Kazimi, 1997;

Santarelli et al., 2003). The 24th FIFA World Cup

Matches and the 14th AG were held in Busan, which is

the second biggest city in Korea, having a population of

3.8 million. Busan Metropolitan City attempted to

reduce emissions from its fleet by reducing vehicle

operation volumes during the two big sports event

periods. Passenger vehicles were allowed to operate in

Busan Metropolitan City areas only on alternate days

during the FIFA World Cup in Busan from 1–6 June

2002. However, the effect on air pollution levels of the

alternate day operation of passenger vehicles (Krawack,

1993; Recker and Parimi, 1999) during the FIFA World

Cup was not as good as expected (Lee and Lee, 2003).

Alternate operation during the short world cup period

of 6 days in early summer or late spring resulted in

increased air pollution levels except in ambient ozone

levels in Busan. The cause of the increase in air pollution

levels had not been identified or analyzed before the

Busan AG started on 29 September 2002. However, the

governments of Busan Metropolitan City had decided to

use the alternate day operation of passenger vehicles

again during the Busan AG period of 29 September–14

October 2002. This was because there was a slight

reduction in air pollution levels in most of the cities

where alternate day operation of passenger vehicles was

used during the FIFA World Cup from 31 May to 29

June, 2002. This study reports the impact analysis on

urban air quality found in the alternative daily use of

passenger vehicles in Busan during the 24th AG period.

We also compare the air pollution levels in Busan during

the alternate operation of passenger vehicles to those in

normal periods (before and after the AG) when alternate

operation was not conducted.

Fig. 1. A location map of air-monitoring stations in Pusan

(Busan), Korea.

2. Methods

About 18,000 participants and officials from 43

countries under the Olympic Council of Asia (OCA)

participated in the 14th Busan AG for 16 days from 29

September to 14 October, 2002. Also, spectators

numbering several tens of thousands per day visited

the AG stadiums to watch games. Passenger vehicles in

Busan were not allowed to operate on the alternative

days during the AG period. This restricted operation of

passenger vehicles was enforced to improve an urban air

quality in Busan during the AG period. The even

number cars, based on the last title number of a car,

were only allowed to operate on the even days and the

odd number cars were also only allowed to operate on

the odd days in Busan during the AG period. The

average use of road vehicles of the alternate day

operations in Busan during the AG period was

calculated by counting the number of passenger vehicles

passing through the measurement points of 6 sites

during the alternate operation periods for the 16 days

and compared to measurements made immediately

before and after the games. The counting of passenger

vehicles passing through the points was conducted

during three periods of the day; morning rush hour

(07:30–09:30), day hour (12:00–14:00), and afternoon

rush hour (17:30–19:30), using manual counts at less

busy traffic points and closed-circuit television (CCTV)

analysis at busy traffic points for every alternate 10min

(10min count and then 10min break). Vehicle speeds

during alternate operation were measured at major

roads including the central and outer areas of the cities

with vehicle speed measurement guns.

This study classified the study periods as ‘‘before’’

(13–28 September 2002), ‘‘during’’ (29 September–14

October 2002), and ‘‘after’’ (15–30 October 2002) the

AG period for the purpose of comparing air pollution

levels. The alternate operation of passenger vehicles was

only conducted during the AG period and is termed

‘‘during’’. Continuous measurements of criteria air

pollutants, such as CO, NO2, SO2, PM10 and O3, were

conducted at 13 monitoring sites in Busan during the

study periods, from 13 September to 30 October 2002.

The air measurement equipment at the monitoring sites

was regularly checked for operation status and cali-

brated according to the preventative maintenance

schedule (DOE, 2003a; MOE, 2003).

This study obtained 1-h average concentrations for

criteria air pollutants as a function of the diurnal

variation at 13 air-monitoring stations in Busan (Pusan)

during the three terms (Fig. 1). The 24-h and 16-day

average levels, based on the information of 1-h average

concentrations of the criteria air pollutants for each

term, were analyzed and compared with those of other

classified terms. In a comparison of the air pollution

levels of the three terms, the concentrations measured on

rainy days with precipitation above 3.5mm per day were

ARTICLE IN PRESSB.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–2338 2325

excluded to evaluate the net effects of the alternate

operation of passenger vehicles. Simple meteorological

data, such as wind speed, relative humidity, and

temperature, were obtained from each air-monitoring

station and compared to the data measured at the Busan

Regional Meteorological Office (BRMO). Major me-

teorological data including average daily maximum

mixing height, ambient ventilation index, sunshine

duration time, precipitation and wind information were

obtained from the data measured at the BRMO located

in Myengryun-dong near the Bugok air-monitoring

station. The wind roses of the three compared periods

were drawn from the wind velocity and direction

measured at the BRMO.

Finally, this study compared the air pollution levels

between two monitoring sites near the AG main

stadiums and at other monitoring sites excluding two

sites near the stadiums. Since PM10 emission informa-

tion from gasoline vehicles is currently not available in

Busan, the emission changes for PM10 could not be

calculated. Also, ozone (O3) is not usually considered as

a primary air pollutant, but a secondary air pollutant

combined with sunlight radiation, nitrogen dioxide

(NO2), nitric oxide (NO), etc (Palmgren et al., 1996).

In this paper, the measured O3 levels are simply matched

with the hydrocarbon emission estimate.

3. Results and discussion

3.1. Vehicle emission analysis and control strategy

Table 1 summarizes a source contribution pattern on

emissions of air pollutants in Busan Metropolitan City

in 2002 (DOE, 2003a; DOE, 2003b). The air emissions

from ships were the most prominent source followed by

emissions from road vehicles. This is because Busan is

the largest port in Korea, as well as one of the busiest

international port cities. This source contribution

pattern is totally different from that of Seoul, in which

85% of the total air emissions come from vehicles

operating on roads. This means that the first priority in

reducing the total air pollution levels in Busan should be

the control of ship emissions. In fact, however, it is not

easy to apply emission control measures to ships because

Table 1

A summary of air pollutant emissions in Busan metropolitan city

Source Vehicle Ship

Air emissions (1000 ton year�1) 120.6 168.3

Relative contribution (wt%) 38.7 54.0

Note: Vehicle means only mobile vehicles operated on roads and ship e

boats, trains, and air planes.

of technological difficulties concerning the fuels, engines,

and air pollution control devices of ships.

Table 2 shows the contribution of mobile vehicles

operated on roads to the total air emissions of each air

pollutant in Busan. The road vehicles were the most

significant sources of the air emissions of carbon

monoxide (CO) and NO2 in Busan. However, the

contribution from the road vehicles to the total air

emissions of hydrocarbons (HCs), fine particulate

(PM10), and sulfur dioxide (SO2) was much less than

that of CO or NO2 in Busan.

Table 3 analyzes emissions of air pollutants from road

vehicles in Busan in 2002 as a function of vehicle type.

About 91% of passenger vehicles, excluding taxies, used

gasoline as a fuel in 2002. These passenger vehicles were

responsible for about 25.5% of the total carbon

monoxide emissions in Busan. Almost 100% of the

taxies used LPG as a fuel and these LPG taxies were

responsible for about 20.9% of the total CO emissions in

Busan. LPG taxies and passenger vehicles excluding

LPG taxies were 7.4% and 56.0% of the total number of

vehicles registered in Busan in October 2002, while air

emissions from them were 18.0 and 23.5wt% of the total

air emissions from road vehicles, respectively. The

contribution of LPG taxies to the total air emissions

from road vehicles was high when compared to the

registered number of LPG taxies. This was due to a

much longer operation period of LPG taxies (about

22 h day�1) compared with the passenger vehicles that

operate 1.0–1.5 h day�1.

About 62% and 36% of the buses registered in Busan

in October 2002, used diesel (430 ppm S in 2002) and

LPG (200 ppm S in 2002), respectively, as their fuel.

Almost 100% of the large buses and 89% of the trucks

operated in Busan used diesel as their fuel. Even though

diesel buses and trucks are only about 24.3% of the total

road vehicle numbers registered in Busan, they were

responsible for 48.5wt% of the total air emissions from

the road vehicles in Busan. About 9.1 and 45.3wt% of

the total air emissions from the road vehicles in Busan

came from all buses and trucks, respectively. Also, all

buses and trucks were responsible for 45.0, 83.0, 39.8,

100, 100wt% of the total emissions of CO, NO2, HCs,

PM10, SO2, respectively, emitted from all the road

vehicles in Busan in 2002. Even though this study

Heating Industry Electricity Total

11.9 11.0 0 311.8

3.8 3.5 0 100

missions include all of the emissions from the operation of ships,

ARTICLE IN PRESS

Table 2

Contribution of vehicle emissions to the total emissions of each air pollutant based on mass in Busan

CO NOx HC PM10 SO2

Total air emissions of pollutant from all sources (1000 ton year�1) 83.0 71.6 54.0 42.3 60.9

Total air emissions of pollutant from vehicles (1000 ton year�1) 70.1 35.3 9.3 5.3 0.6

Vehicle contribution to the total air emissions of pollutant (wt%) 84.5 49.3 17.2 12.5 9.9

Note: Vehicle means only mobile vehicles operated on roads.

Table 3

Contribution of vehicle emissions to the total air emissions of each pollutant in Busan

CO NOx HC PM10 SO2

Total air emissions from passenger cars (1000 ton year�1) 21.2 3.7 3.5 0 0.04

Contribution to total air emissions of pollutant (wt%) 25.5 5.2 6.5 0 0.07

Total air emissions from LPG taxies (1000 ton year�1) 17.3 2.3 2.1 0 0

Contribution to total air emissions of pollutant (wt%) 20.9 3.1 3.9 0 0

Total air emissions from buses (1000 ton year�1) 7.6 6.1 0.9 1.1 0.2

Contribution to total air emissions of pollutant (wt%) 9.1 8.6 1.6 2.6 0.3

Total air emissions from trucks (1000 ton year�1) 24.0 23.2 2.8 4.2 0.4

Contribution to total air emissions of pollutant (wt%) 28.9 32.4 5.3 9.9 0.6

Table 4

Estimated reduction effects of air pollution levels by alternate operation of passenger vehicles in Busan

Degree of reduction (�) or increase (+) of pollutant (%)

CO NO2 HC PM10 SO2 Average

Estimation by participation and emission info.a �12.2 �2.5 �3.1 0 �0.03 �3.6

Estimation by participation and emission info.b �11.3 �1.6 �2.9 0 0 �3.2

aEstimation based on the emissions from all passenger cars including LPG taxies.bEstimation based on the emissions from all passenger cars excluded LPG taxies.

B.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–23382326

analyzed the impacts on urban air quality (UAQ) by

controlling operation of passenger vehicles, the control

of air emissions from buses and trucks would be a more

effective way to improve the UAQ in Busan. In reality,

however, it is not easy to implant the operation

reduction of buses and trucks for the UAQ improve-

ment of a short period. This is because most buses and

trucks are used as a means for public and industrial

transportation, respectively, which were essential even

during the AG period. Reductions of HCs from

passenger vehicles, however, are more important than

buses or trucks.

3.2. Estimated emission reduction of the alternate

operation

The average usage rate of the alternate operation of

passenger vehicles during the AG period in Busan, based

on the passenger vehicle numbers registered in Busan

until October 2002 was 95.370.8%. Table 4 represents

the estimated emission reduction rates of air pollutants

based on both the contribution of passenger vehicles to

the total emissions of each air pollutant shown in Table

3 and the average usage rates of passenger vehicles of

alternate operation (Lee and Longhurst, 1993). If the

alternate operation of passenger vehicles, excluding

LPG taxies, were conducted in Busan, the greatest

emission reduction effects would be observed in CO

levels followed by HC and NO2 levels.

When evaluated on the basis of the emission factors of

unleaded gasoline vehicles in Korea (Haan and Keller,

2000; NIER, 1990), there would be no reductions in

PM10 and SO2 levels. The average estimated emission

reductions of all criteria air pollutants by the alternate

operation of passenger vehicles would decrease from 3.6

to 3.2wt%. However, these estimated reduction levels

ARTICLE IN PRESSB.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–2338 2327

would be affected by changes in vehicle speed accom-

panied by traffic volume reductions, meteorological

conditions, type of vehicle and fuel, etc, which are not

included in this simple estimate. Also, the increases in

buses and taxies to make up reduction in transportation

means by the alternate operation of passenger vehicles

can offset the air emission reduction effects by the

alternate operation. Even though there might be errors

included in the estimate, it would be still useful for the

purpose of a simple evaluation estimate in air emission

reduction of the alternate operation effects of passenger

vehicles.

3.3. Rain precipitation and wind effect

Table 5 summarizes the meteorological conditions,

excluding the data observed on rainy days with

precipitation of above 3.5mm per day, of the three

periods compared in this study. All three terms had

rainy days ranging from 2 to 3 days which had rain

precipitation above 3.5mm and the total rain precipita-

tion during these heavy rainy days ranged from 44.0 to

78.0mm. The authors have found that precipitation,

such as rainfall, significantly affected air pollution levels

under a similar alternate operation of passenger vehicles

during the FIFA World Cup (Lee and Lee, 2003). This

study also found that heavy rain precipitations during

the alternate operation as well as normal periods which

did not have alternate operation, significantly affected

air pollution levels (Fig. 2).

Fig. 2 shows the rainfall effects on air pollution levels

during the study period by comparing air pollution

levels on rainy days, which had rain precipitation above

8.0mm per day, with those on the days that did not have

a significant amount of rain. The degree of air pollution

reduction effects by rainfall under the alternate opera-

tion (during) was lower than that under the normal

periods (before and after). The relatively low rainfall

Table 5

A summary of the meteorological conditions of three compared perio

Meteorological conditions Before

Average sunshine duration time (h)a 6.173.5

Average daily temperature (1C)a 20.770.8

Average daily relative humidity (%)a 67.574.1

Average daily rainfall (mm), (dayp3.5mm) 0.370.1,

Average daily rainfall (mm), (day43.5mm) 39.0725.

Total rain precipitation (mm), (dayp3.5mm) 0.9, (3)

Total rain precipitation (mm), (day43.5mm) 78.0, (2)

Average daily maximum mixing height (m) 1612.576

Average daily ventilation index (m2 s�1) 3743.871

Average daily wind speed (m s�1)a 3.671.0

aExcluded the data measured on days with precipitation above 3.5

effects during the alternate operation, as compared to

that during the normal periods, was due to a significant

increase of air pollution levels observed during the

alternate operation period (discussed below). Rain

precipitation had the largest effect on the reduction in

SO2 levels and the least on the ambient O3 levels. The

average levels of ambient O3 on the days with significant

rain precipitation above 3.5mmday�1 during the

normal periods were not lower, but slightly increased,

depending upon monitoring sites and meteorological

conditions, as compared to those on the days that did

not have significant rainfall.

Fig. 3 shows the average wind roses of three compared

periods. The wind patterns in the term during the

alternate operation were quite different from those in

the normal periods (terms before and after). Thus, the

alternate operation period might have different sources

of air pollutants from the normal periods. In particular,

the normal periods might have a more dilution effect by

winds blowing from the sea than the alternate operation

periods. This fact was identified in detailed analysis of

the average daily maximum mixing height and ambient

ventilation index of two terms shown in Table 5. This

study was based on the average values of the measure-

ment data obtained at 13 monitoring sites, which well

represent various areas through Busan city for 16 days

in each term. However, there might be a little difference

in air pollution sources between the normal and

alternate operation periods because of quite different

wind patterns between them.

3.4. Measured effects of air pollution levels under the

alternate operation

3.4.1. Total effects

In order to evaluate the net effect on air pollution

levels under the alternate operation of passenger

vehicles, this study excluded the measurement data

ds

During After

7.671.3 7.372.0

19.672.2 12.873.9

66.378.1 50.0710.0

(3) 0.470.2, (2) 1.872.4, (2)

5, (2) 22.074.2, (2) 20.3716.4, (3)

0.7, (2) 3.6, (2)

44.0, (2) 61.0, (3)

52.0 1268.87541.3 —

826.6 3243.871634.2 —

2.970.9 3.671.3

mm in Busan.

ARTICLE IN PRESS

- 40

- 30

- 20

- 10

0

10

20

CO NO2 O3 PM10 SO2

Air Pollutant

Dec

reas

e / I

ncre

ase

(%)

before during after

Fig. 2. Rain precipitation effect of air pollution levels under the study period.

Fig. 3. Average wind roses of the three compared periods.

B.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–23382328

obtained on rainy days, having precipitation of above

3.5mm per day, from the air pollution levels obtained in

the period of each term. Figs. 4a,5a,6a,7a,and 8a

compare the average CO, NO2, O3, PM10, and SO2

levels measured at 13 air-monitoring sites under the

study periods, that is, before, during, and after the

alternate operation period of passenger vehicles in

Busan. Figs. 4b,5b,6b,7b and 8b represent the average

levels of CO, NO2, O3, PM10, and SO2, based on a

combination of the data measured at 13 air-monitoring

sites in Busan, as a function of diurnal variation during

the study periods. Even though there was a variation

among the monitoring sites, all the average air pollution

levels measured in Busan during the alternate operation

period significantly increased as compared to those

measured during the normal periods (terms before and

after) that did not have alternate operation.

Table 6 summarizes the change effects of air pollution

levels measured at 13 air-monitoring sites during the

alternate operation of passenger vehicles in Busan. The

highest increase during alternate operation was observed

in average levels of PM10 followed by NO2 levels. There

was a significant increase in SO2 and CO levels, too.

These increases are almost opposite to the estimated

results (Table 4) based on the relative contribution of

passenger vehicles to the total emissions of air pollutants

in Busan and the average usage rates of passenger

vehicles of alternate operation. All the air pollution

levels (based on each 24-h average) measured during the

term after the alternate operation period, except O3

levels, were similar to or slightly higher than those

measured during the term before. However, the average

O3 levels of the daytime during the term before were

higher than those during the term after. These phenom-

ena are well matched with an increasing trend in criteria

air pollution levels, except ozone levels that had a

decreasing trend, with the time progress of the fall

season in Korea.

Table 6 also presents the mean data of air pollution

levels measured at 12 monitoring stations in Ulsan, a

neighboring city in which a similar alternate operation

was not conducted during the alternate operation period

ARTICLE IN PRESS

0.0

2.0

4.0

6.0

8.0

10.0

12.0

1 2 3

(a)

4 5 6 7 8 9 10 11 12 13 14

Monitoring Site

Avg

. Con

c.(p

pm)

before during after

0.0

2.0

4.0

6.0

8.0

10.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Time (hour)

Avg

. Con

c.(p

pm)

before during after

(b)

Fig. 4. (a) Average CO concentrations at monitoring sites of the compared three periods and (b) average diurnal CO concentrations of

the compared three periods.

B.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–2338 2329

in Busan. Ulsan is a port city located in about 30 km

from Busan and meteorological conditions in Ulsan are

usually quite similar to those in Busan. The measured

average daily wind speed and ambient ventilation index

decreases were 15.4% and 9.8%, respectively, in Ulsan;

those decreases were 19.4% and 13.3%, respectively,

during the alternate operation in Busan. The air

pollution levels in Ulsan during the AG also increased

as compared to those before the AG like Busan. This

increase might be related to a change of meteorological

conditions, such as decrease in wind speed and ambient

ventilation index. However, the degree of increase in

Ulsan was much less than that in Busan. The more

significant increase of air pollution levels in Busan than

that in Ulsan during the AG might be related to the

alternate operation of passenger vehicles in Busan.

3.4.2. Vehicle speed and type effects

A significant increase in average PM10 and NO2 levels

was observed during the alternate operation. One of the

causes of increases in PM10 and NO2 levels may have

been associated with increases in vehicle speed due to

traffic volume reductions. The average vehicle speed

during normal periods without alternate operation in

Busan was approximately 24.6 kmh�1 (an average of

central and suburban areas) and during alternate

operation was approximately 28.3 kmh�1. Emission

changes of nitrogen oxides (NOx) only by vehicle speed

change is often evaluated by the following empirical

formula (NIER, 1990):

NOx ¼ aV2 þ bV2 þ cV þ d,

where, a ¼ �6:4611� 10�5; b ¼ 0:00578; c ¼ �0:1584;d ¼ 1:87638:When evaluated by this formula, the NOx concentra-

tions under alternate operation in Busan would increase

approximately 17.9% (Palmgren et al., 1996). In a

simple calculation excluded the NOx emission reduction

estimate of 2.5% by the alternate operation of passenger

vehicles, the net increase of NOx concentrations by a

vehicle speed increase could be 15.4%. However, this

evaluation is easily affected by the NOx emission

increase by operation volume increase of LPG taxies

and diesel vehicles to make up the operation decrease of

passenger vehicles during the alternate operation. In

addition, increase of diesel vehicles such as buses and

trucks can significantly increase the PM10 level (Table 3).

According to a recent study of road dust concentrations

ARTICLE IN PRESS

0.

(a)

0

10.0

20.0

30.0

40.0

50.0

60.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Monitoring Site

Avg

. Con

c.(p

pb)

before during after

before during after

0.0

10.0

20.0

30.0

40.0

50.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Time(hour)

Avg

. Con

c.(p

pb)

(b)

Fig. 5. (a) Average NO2 concentrations at monitoring sites of the compared three periods and (b) average diurnal NO2 concentrations

of the compared three periods.

B.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–23382330

as a function of vehicle speed, a vehicle speed increase

can significantly increase particulate concentration

including PM10 level due to the increased suspension

of road dust or particulate (Kuhns et al., 2003; Harrison

et al., 2003). Thus vehicle speed improvement by

alternate operation of passenger vehicles might have

affected the increase of PM10 and NO2 levels.

According to the Seoul government (Kat News, 2003),

the traffic volume of total vehicles by alternate operation

during the FIFA World Cup in Seoul was reduced by

approximately 19.2%. The alternate operation situa-

tions during the FIFA World Cup in Seoul would have

been very similar to those during the AG in Busan. Also,

the traffic volume of LPG taxies and diesel vehicles

during the AG in Busan increased by approximately

10% to make up for a reduction in passenger vehicle

operation for transportation of spectators or visitors to

the games, and to transport more freight due to vehicle

speed increases (Lenschow et al, 2001; Romilly, 1999).

In addition, the relative contribution from diesel vehicles

to the total air emissions in Busan was higher than that

in Seoul. When simply calculated based on a 10%

operation volume increase of LPG taxies, buses, and

trucks under the alternate operation of passenger

vehicles in Busan, the degree of the increase of CO,

NO2, O3, PM10, and SO2 levels would be 5.9, 4.4, 1.1,

and 1.3, and 0.1wt%, respectively. Therefore, an

increase of air pollution levels during alternate operation

in Busan might be partially related to the operation

volume increases of other vehicles such as taxies and

buses. In particular, increased levels in NO2, PM10, and

SO2 concentrations accompanied by increases in LPG

taxies, buses and trucks substantially exceeded the

reduction levels expected by the alternate operation of

passenger vehicles in Busan (Carslaw and Beevers,

2002).

3.4.3. Comparison of air pollution levels between the

stadium and other areas

Figs. 9a–e compare the averaged diurnal variation of

CO, NO2, O3 PM10, and SO2 levels measured at the

monitoring sites near two large stadiums for the AG and

at other sites excluding the two sites near the stadiums.

The average CO levels near the stadiums were higher

than those at other areas during normal periods

(Fig. 9a). There was a significant increase of average

ARTICLE IN PRESS

0.0

10.0

20.0

30.035.0

5.0

15.0

25.0

40.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14Monitoring Site

Avg

. Con

c.(p

pb)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Time(hour)

Avg

. Con

c.(p

pb)

(a)

before during after

before during after

(b)

Fig. 6. (a) Average O3 concentrations at monitoring sites of the compared three periods and (b) average diurnal O3 concentrations of

the compared three periods.

B.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–2338 2331

CO levels at other areas during alternate operation as

compared to those before. However, there was no

significant difference of average CO levels at the areas

near the stadiums, except periods from midnight to

morning rush hours, between the terms before and

during. The average NO2 levels both near the stadiums

and at other areas during alternate operation signifi-

cantly increased as compared to those before the

alternate operation (9b). In particular, the degree of

increased levels of nitrogen dioxide nearby the stadiums

was more than twice that at other areas. This high

increase at the stadium areas might be due to the

operation volume increases of buses to transport the

spectators and participants during the AG. Under the

alternate operation of passenger vehicles, the average

ambient O3 levels during afternoon hours (12:00–19:00)

at other areas were much higher than those at stadium

areas (9c). The PM10 levels during the nighttime and

morning hours at other areas were higher than nearby

the stadiums during the alternate operation (Fig. 9d).

This was probably due to more increased vehicle speeds

at other less-congested areas rather than the congested

stadium areas. For example, there was an increase of

approximately 28.1% in the average vehicle speed at the

stadium areas; however, vehicle speed increases of

approximately 39.5% were observed in the outside areas

of Busan.

A significant increase of average SO2 levels was

observed near the stadiums rather than at other areas

during alternate operation as compared to that before

alternate operation (Fig. 9e). In particular, a significant

peak increase of SO2 levels was identified during the

morning hours, from 8 to 10, which combined the

morning rush hours and the significant volume opera-

tion increases of buses to transport spectators or

participants to the stadiums at the games. As most of

these buses used diesel fuel, they were responsible for the

peak increase of SO2 levels at the stadium areas during

the alternate operation period.

3.4.4. Ozone levels

There was a large variation in the ambient O3 levels

among 13 monitoring sites during the alternate opera-

tion. The 24-h average levels of the ambient O3 showed a

slight increase due to a large increase of 68.4% at one

monitoring site as compared to other sites. However,

there was a slight decrease of 2.9% in the 24-h median

level of the ambient O3 during the alternate operation

periods as compared to that of the terms before and

after. This means that the alternate operation of

ARTICLE IN PRESS

0.0

20.0

40.0

60.0

80.0

100.0

120.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Monitoring Site

0.0

20.0

40.0

60.0

80.0

100.0

1 3 5 7 9 11 13 15 17 19 21 23

Time(hour)

Avg

. Con

c.(u

g/m

3 )A

vg. C

onc.

(ug/

m3 )

before during after

before during after

(a)

(b)

Fig. 7. (a) Average PM10 concentrations at monitoring sites of the compared three periods and (b) average diurnal PM10

concentrations of the compared three periods.

0.02.04.06.08.0

10.012.014.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14Monitoring Site

0.0

2.0

4.0

6.0

8.0

10.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Time (hour)

Avg

. Con

c.(p

pb)

Avg

. Con

c.(p

pb)

before during after

before during after

(a)

(b)

Fig. 8. (a) Average SO2 concentrations at monitoring sites of the compared three periods and (b) average diurnal SO2 concentrations

of the compared three periods.

B.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–23382332

ARTICLE IN PRESS

Table 6

A change summary of air pollution levels measured at 13 air-monitoring sites during the alternate operation of passenger vehicles in

Busan as compared to those before the alternate operation

Degree of reduction (�) or increase (+) of pollutant (%)

CO NO2 O3 PM10 PM10c SO2 Average

Arithmetic mean (AM)a +26.2 +47.8 +3.3 +53.8 +52.0c +26.3 +31.5

Mediana +27.3 +44.2 �2.9 +54.3 +70.2c +30.6 +30.7

Standard deviationa +23.9 +25.1 +21.6 +14.8 +14.8c +26.9 +22.5

Maximuma +83.8 +84.1 +68.4 +85.5 +17.7c +74.6 +79.3

Minimuma�16.3 �1.4 �19.6 +26.5 +41.1c �16.1 �5.4

Arithmetic mean in Ulsanb +14.1 +17.2 +1.4 +36.3 +36.3 +1.1 +14.0

AM difference (Busan–Ulsan) +13.2 +30.6 +1.6 +17.5 +15.7 +25.2 +17.0

aExcluded the data measured on the days with precipitation above 3.5mm in Busan.bMean data measured at 12 air-monitoring sites in a neighboring city, Ulsan, during the same period.cExcluded the data measured on the days with slight Asian dust and precipitation above 3.5mm in Busan.

B.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–2338 2333

passenger vehicles could lead to a reduction of the

ambient O3 levels by reducing air emissions of ozone

precursors such as hydrocarbons (Tables 3 and 4,

Derwent et al., 2003).

Table 7 shows a detailed analysis of the ambient O3

levels as a function of diurnal variation during both the

alternate and normal (terms before and after) operation

periods of passenger vehicles. The O3 levels of the

daytime or the afternoon period (12:00–19:00) under the

alternate operation (term during) were significantly

higher than those of the terms before and after; 22.7%

increase as compared to the before. The increase in the

ambient O3 levels of the daytime or the afternoon period

might be due to the longer average sunshine duration

time and the weaker average in wind speed during the

alternate operation as compared to those of the terms

before and after (Table 5). In addition, the increased O3

levels are possibly affected by the significant increase in

NO2 concentrations during the alternate operation

period. The ambient O3 levels of the nighttime

(21:00–06:00) or low-ozone period during the alternate

operation, however, were significantly reduced as

compared to those of the terms before and after;

28.1% decrease as compared to the before. This trend

which has an afternoon increase and a nighttime

decrease of the ambient O3 levels during alternate

operation (AG) was very similar to that of the ambient

O3 levels observed during the FIFA Korea–Japan World

Cup in which a similar alternate operation of passenger

vehicles was conducted in Busan in early June 2002

(Fig. 10).

At this moment, this study did not identify the exact

cause of the daytime increase and nighttime decrease in

the ambient O3 level during the alternate operation.

Also, the ozone formation factors and concentration

isopleths related to NOx and HCs in Busan were not

well characterized yet. In general, however, the ambient

ozone formation is strongly related to the ratios of HC/

NOx and the resulting isopleths. According to a study of

the National Institute of Environmental Research

(NIER, 1990) in Korea, the emission changes of HCs

only by vehicle speed change is often calculated by the

formula, (vehicle speed)�0.9212. Based on this formula

and the observed vehicle speed increase from 26.0 to

33.3 kmh�1, the reduction of 20.3% in HCs emissions is

calculated. When the emission reduction levels of 3.1%

by the alternate operation of passenger vehicles is also

considered (Table 4), the total emission reduction in

HCs levels is simply obtained about 23.4%. As discussed

in the previous section, however, the NOx level increased

during the alternate operation. Thus, there might be a

significant change in the ratios of HCs/NOx during the

alternate operation as compared to the normal periods.

This change is more significant during the daytime than

the nighttime under the alternate operation, as com-

pared to the normal periods. The ratios of HCs/NOx

during the daytime would be much lower than those

during the nighttime under the alternate operation.

Therefore, this study can lead to a conclusion that the

daytime increase and nighttime decrease in the ambient

O3 level in Busan during the alternate operation were

significantly affected by a change of the ratios of HCs/

NOx. The ambient ozone formation also could be

affected by degrees of sunshine strength and duration

time, temperature, wind speed, ambient ventilation and

mixing, moving downward the stratospheric ozone in

Busan.

3.4.5. Weekday and weekend effects

Table 8 compares the weekday and weekend effects

in air pollution levels between the terms before and

during the alternate operation of passenger vehicles. On

ARTICLE IN PRESS

0.0

2.0

4.0

6.0

8.0

10.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24A

vg. C

onc.

(ppm

)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Avg

. Con

c.(p

pb)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Avg

. Con

c.(p

pb)

0.0

20.0

40.0

60.0

80.0

100.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Avg

. Con

c.(u

g/m

3 )

0.0

5.0

10.0

15.0

1 3 5 7 9 11 13 15 17 21 23

Time(hour)

Time(hour)

Time(hour)

Time(hour)

Time(hour)

Avg

. Con

c.(p

pb)

(a)

(b)

(c)

(d)

(e)

19

before-others during-others before-stadium during-stadium

Fig. 9. (a–e) Average diurnal concentrations of air pollutants nearby the stadiums and at other areas of the compared two periods

(before and during).

B.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–23382334

Saturday of the study period, more than 50% of the

workers in Busan worked from 9:00 to 13:00 and the rest

of the people did not go to work. Thus, Saturday was

not categorized as a weekday or a weekend in this study.

The weekend shown in Table 8 means only Sunday and

the weekday means Monday to Friday. Busan had a

distinct weekend effect which shows a significant

decrease in average air pollution levels as compared to

weekdays. The largest weekend reductions in NO2 and

SO2 levels, 32% and 32% reduction, respectively, as

compared to weekdays, and the least weekend reduction

in O3 levels, 5% reduction, were observed during the

ARTICLE IN PRESS

0.0010.0020.0030.0040.0050.0060.0070.00

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Time (hour)

Avg

. Con

c. (p

pb)

Normal (June) Alternate operation Normal (May)

Fig. 10. Average diurnal O3 concentrations of the three periods associated with the FIFA World Cup Game period [May (before) and

June (after): monthly average, alternate (during): 6-day average].

Table 7

Statistical analysis of hourly ozone data of three compared periods for 13 sites (n ¼ 208)

Hourly average ozone data of low ozone period (morning hour)

Hour 1 2 3 4 5 6 7 8 Average

Before 20.6711.6 21.7711.7 22.6711.8 22.5712.2 21.7712.0 19.0712.0 14.9710.7 13.879.8 19.6711.5

During 14.4711.9 15.0712.5 15.4712.5 15.6712.5 15.4713.7 14.0714.0 10.9711.8 12.0711.7 14.1712.6

After 20.7715.1 22.4716.2 23.5716.6 24.1716.3 23.8716.2 22.2715.5 18.4713.1 15.9711.5 21.4715.1

Hourly average ozone data of high ozone period (afternoon hour)

Hour 11 12 13 14 15 16 17 18 Average

Before 29.4711.3 35.6713.5 40.0714.0 41.4715.1 40.0715.0 38.4714.7 36.2715.9 32.1714.4 36.6714.2

During 30.8714.8 39.8715.2 48.4716.8 52.1717.9 52.1719.4 50.2719.7 46.5718.7 39.5717.7 44.9717.5

After 24.4711.3 28.6710.4 32.6710.8 34.2711.9 33.7711.9 32.6712.0 28.7712.1 22.8711.8 29.7711.5

B.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–2338 2335

term before. Even though the average NO2, SO2, and

PM10 levels on Saturday were not reduced as much as

the reduction on Sunday, they were also significantly

reduced as compared to those during the weekdays of

the term before. The average O3 levels on Saturday were

almost the same as those on the weekdays. The average

CO levels on Saturday increased as compared to those

on the weekdays of the term before.

Even though the reduction levels in air pollution on

the weekends under the alternate operation were smaller

than those in the term before, Busan had also a distinct

weekend reduction effect, ranging from 4% to 12%

reduction, except CO (2% increase) as compared to

weekdays. The reduction in the weekend effect of the air

pollution levels under the alternate operation might be

related to the lower maximum mixing height (32.9%

reduction as compared to weekdays) on the Sundays of

the alternate operation than that (12.6% reduction) on

the Sundays of the normal periods. All the air pollution

levels, except O3 levels, on the Saturdays under the

alternate operation significantly increased as compared

to those in the weekdays under the alternate operation.

The highest increase of 22.3% in CO levels and the

lowest increase of 9.6% in PM10 levels were observed on

the Saturdays. The average O3 levels on the Saturdays

under the alternate operation slightly decreased (7.9%)

as compared to those in the weekdays. The increase on

the Saturdays under the alternate operation was

probably due to the significant reduction in average

daily ambient ventilation index and maximum mixing

height, 63.0% and 33.2%, respectively, as compared to

those on weekdays.

3.4.6. Ambient mixing and ventilation effects

One of main causes of the large difference in air

pollution levels between the normal periods and the

during the alternate operation of passenger vehicles was

due to the change of meteorological factors such as

sunshine duration time, wind velocity, maximum mixing

height (MMH) and ambient ventilation index (AVI)

(Table 5). The term during under the alternate operation

showed significantly lower values in average daily wind

velocity, MMH, and AVI than the term before. Thus the

ambient mixing or dilution effect significantly reduced

ARTICLE IN PRESS

Table 8

A summary of air pollution levels as a function of week days and weekend variations between the terms of before and during the

alternate operation of passenger vehicles in Busan

Period Air pollutant CO NO2 O3 PM10 SO2

Concentration unit ppm ppb ppb mgm�3 ppb

Time breakdown Avg7SD Avg7SD Avg7SD Avg7SD Avg7SD

Before Period total 5.571.3 23.376.9 26.474.3 44.0712.9 4.771.2

Weekdaya 5.971.4 25.376.9 26.674.2 47.5714.1 5.071.2

Saturday 4.570.4 19.875.5 26.476.7 38.375.0 4.670.4

Sunday 4.971.0 17.173.6 25.373.8 33.771.5 3.470.8

Weekend/weeka 0.83 0.68 0.95 0.71 0.68

During Period total 6.971.1 33.874.8 26.676.4 78.3730.0 6.672.0

Weekdaya 6.771.1 34.075.3 27.776.6 68.5716.0 6.772.3

Saturday 8.270.3 37.572.5 25.574.7 75.171.0 7.471.8

Sunday 6.671.1 30.771.1 23.377.1 65.878.6 6.071.0

Weekend/weeka 1.02 0.90 0.88 0.96 0.90

Ratio (during/before) Period total 1.25 1.45 1.01 1.78 1.40

Weekdaya 1.14 1.34 1.05 1.44 1.34

Saturday 1.82 1.89 1.01 1.96 1.61

Sunday 1.35 1.79 0.92 1.95 1.76

Weekend/weeka 1.23 1.32 0.93 1.35 1.32

aOn Saturday of the study period, more than 50% of the workers in Busan worked from 9:00 to 13:00 and the rest of people did not

work (The weekend: only Sunday, the week days: Monday through Friday).

B.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–23382336

during the alternate operation. Even though there were

lower air emissions resulting from significant reduction

in volume of passenger vehicles as compared to the

normal operation periods, the emission reduction effect

from passenger vehicles would not exceed the increase

effect resulting from the lower ambient dilution or

mixing.

There was also a significant difference in major

meteorological conditions, which greatly affect in air

pollution levels, between the first week and the second

week under the alternate operation (Table 9). The first

week under the alternate operation had significantly

lower values in average daily MMH and AVI, but

slightly higher values in average daily ground wind

speed and sunshine duration time as compared to the

reference week under the normal operation. Thus, the

first week showed significant increases in all the air

pollution levels as compared to the reference week. The

largest increase during the alternate operation was

observed in average levels of PM10 followed by SO2

and NO2 levels. There was a slight Asian dust activity

for 2 days of the first week. Thus, the largest increase in

PM10 might be due to the Asian dust effect. Even though

the PM10 data measured on the days, which was affected

by the Asian dust activity, were excluded for a net

evaluation of an average PM10 level increase, there was a

significant increase of 45.5% in PM10 level, which is

similar to the SO2 increase level of 45.2%, during the

first week under the alternate operation.

The second week under the alternate operation

showed slightly lower values in average daily MMH

and ground wind speed, but almost same average AVI as

compared to the reference week under the normal

operation. Thus, the second week would be a good

week for a net evaluation of change in air pollution

levels under the alternate operation of passenger

vehicles. The observed increase effect in air pollution

levels for the second week, as compared to the reference

week under the normal operation of passenger vehicles,

was much smaller than the first week. There was slight

increase in SO2, NO2 and PM10 levels during the second

week, but there was no increase in CO levels as

compared to the reference week. Because the second

week was still under the alternate operation period, the

significant air emission reduction would be expected.

Thus, this slight increase also could be considered as a

significant increase in air pollution levels. The 24 h-

average O3 levels during the second week significantly

reduced. This reduction in O3 levels during the second

week might be due to the shortening in the sunshine

duration time as compared to the reference week.

4. Summary of findings

An analysis of the impact on urban air quality of

alternate operation of passenger vehicles during the 14th

Busan Asian Games in Korea, resulted in the following.

ARTICLE IN PRESS

Table 9

A change summary of air pollution levels during the alternate operation of passenger vehicles in Busan as compared to those in the

reference period before the alternate operation

Compared item and period Before (normal) During (alternate operation)

Reference week 1st week (low ventilation) 2nd week (similar ventilation)

Data Data Change Data Change

Meteorological conditions

Max mixing height (m) 18007593 11007514 �38.8% 15177546 �15.7%

Ventilation index (m2 s�1) 363371882 285071668 �21.6% 356771675 �1.8%

Wind speed (m s�1) 3.071.1 3.271.0 +6.7% 2.7707 �10.0%

Sunshine duration time (h) 6.873.1 7.671.8 +11.8% 7.670.9 +11.8%

Air pollution levels

CO (ppm) 6.371.8 7.571.3 +19.0% 6.370.9 0.0%

NO2 (ppb) 29.477.0 37.074.8 +25.9% 32.075.3 +8.8%

O3 (ppb) 29.272.4 33.075.8 +13.0% 22.672.9 �22.6%

PM10 (mgm�3)a 56.0713.8 107.8737.2a +92.5%a — —

PM10 (mgm�3) 56.0713.8 81.579.0 +45.5% 58.1710.0 +3.8%

SO2 (ppb) 5.371.0 7.772.7 +45.2% 5.972.0 +11.3%

Note: Data was collected from Monday to Saturday in each week which did not have rain precipitation above 3.5mm.

Change means percentage change of the values during the alternate operation of passenger vehicles as compared to the values of a

reference week before the alternate operation.aIncluded PM10 data measured on two days which showed Asian dust activity day.

B.-K. Lee et al. / Atmospheric Environment 39 (2005) 2323–2338 2337

In a simple estimate of emission reduction, based on

the contribution rates of the passenger vehicles to total

air emissions and the average usage rates (95.3%) of

passenger vehicles of alternate operation in Busan,

about 11.3, 1.6, and 2.9wt% of the total CO, NO2,

and HC emissions, respectively, were reduced.

All the average air pollution levels, except O3 levels,

measured at 13 air-monitoring stations during the

alternate operation period of passenger vehicles in

Busan significantly increased as compared to those

measured during normal periods. The main cause of

these increases was strongly related to a change of

meteorological conditions; reduction in average daily

ambient ventilation index, maximum mixing height, and

wind velocity during the alternate operation period in

Busan. There was a slight decrease in the daily median

level (based on 24 h) of the ambient O3 during the

alternate operation period as compared to that before

and after. The daytime increase and nighttime decrease

in the ambient O3 level during the alternate operation

was significantly affected by a change of the ratios of

HCs/NOx in Busan.

There was a more significant increase of NO2 and SO2

levels near the stadiums than those in other areas. This

increase might be due to operation volume increases for

buses to transport spectators and participants to the

games. The more significant increase of PM10 levels

during the nighttime and morning hours at other areas

than near the stadiums is probably due to a more

significant increase in vehicle operation speeds at other

less-congested areas rather than the congested stadium

areas under alternate operation.

Acknowledgements

This study was funded by the University of Ulsan,

Korea. The authors are also thankful for the assistance

provided by the staffs of the Institute for Environment

and Health Research in Ulsan, the Ulsan Development

Institute, and the Department of Environment in the

Metropolitan City of Busan.

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