The Scientific World Journal

Volume 2014 (2014), Article ID 824301, 18 pages

http://dx.doi.org/10.1155/2014/824301

Research Article

Characterization of Odorous Compounds (VOC and Carbonyl Compounds) in the Ambient Air of Yeosu and Gwangyang, Large Industrial Areas of South Korea

Young-Kyo Seo, Lakshmi Narayana Suvarapu, and Sung-Ok Baek

Department of Environmental Engineering, Yeungnam University, Gyeongsan-si 712 749, Republic of Korea

Received 18 July 2014; Accepted 20 August 2014; Published 17 September 2014

Academic Editor: Ki-Hyun Kim

Copyright © 2014 Young-Kyo Seo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract.

Odorous compounds play an important role in air pollution in industrial areas and the residential areas surrounding them. This study measured the odorous volatile organic compounds (VOC) and carbonyl compounds at Yeosu and Gwangyang, two large industrial areas of South Korea, during four seasons of 2008-2009. Along with these two cities, the same odorous compounds were measured at Suncheon, which was selected as a control site. The concentrations of VOC and carbonyl compounds that were listed as odorous air pollutants by the Ministry of Environment of South Korea are discussed. Benzene and formaldehyde were included in the target analytes because of their carcinogenic nature. Most researchers only examined the concentration of odorous compounds in ambient air but the present study evaluated the odor intensity, which is a new parameter that will help better understand the precise odor perceived by people. This paper describes the seasonal variations and spatial distribution of the above-mentioned odorous compounds at the specified sites. Pearson correlation coefficients between the odorous compounds and other air pollutants, such as ozone, CO, SO₂, NO₂, and PM₁₀, and meteorological conditions, such as temperature and wind speed, provide the source information of odorous VOC and carbonyl compounds.

1. Introduction

The monitoring of odorous compounds in ambient air is an important task to environmental researchers because of the presence of some toxic volatile organic compounds (VOC) and carbonyl compounds in odorous compounds. The VOC and carbonyl compounds present in malodors have adverse effects on the air quality in the surrounding areas of the sources [1] as well as on health of the people residing near the sources. The major sources for odorous compounds include agricultural waste, food processing industries [2, 3], composting of municipal solid wastes [4], livestock production industries [5], semiconductor industries [6], and the incomplete combustion of hydrocarbon fuels in a range of industries [7]. The use of ethanol in industries also results in the release of odorous carbonyl compounds into the atmosphere [8]. Therefore, many countries are struggling to develop effective odor regulations or guidelines to decrease their concentrations in ambient air [2]. In recent years, many researchers have reported the concentrations of odorous compounds in the atmosphere in Korea and around the world with respect to their hazardous and/or toxic nature to humans [7–12]. In South Korea, the Ministry of Environment identifies 22 compounds as malodourous in the atmosphere [13]. Among these 22 malodorous compounds, 50% belong to VOC (toluene, styrene, m,p,o-xylenes, methyl isobutyl ketone, and ethyl acetate) and carbonyl compounds (acetaldehyde, propanal, n-butanal, n-valeraldehyde, i-valeraldehyde, and methyl ethyl ketone).

In addition to odor, the carbonyl compounds have also attracted the attention of researchers to measure their concentrations in ambient air because of their ozone formation potential by means of photochemical reactions and their adverse health effects on humans [14, 15].

In the present study, ambient air samples were collected to measure the concentrations of odorous compounds including VOC and carbonyl compounds in two large industrial cities of South Korea, namely, Yeosu and Gwangyang. To compare the concentrations of the selected compounds at these cities, Suncheon, which is a purely residential site and almost 25 km away from industrial complexes, was chosen as the control site (Figure 1).

Figure 1: Location of the sampling sites at Yeosu, Gwangyang, and Suncheon.

Yeosu (34°44′N 127°44′E), which is situated in Jeolla province, South Korea, is an important industrial city. The population is approximately 300,000 according to the 2009 census and has an area of 503.33 km². This city has more tourist attractions as an ocean resort and is also close to the Yeocheon Industrial Complex. This importance made this city a host to the 2012 World Expo (http://en.wikipedia.org/wiki/Yeosu). The major industries located in this city are related to oil refineries and petrochemicals. In Yeosu, ambient air samples were collected at two sites: pure industrial site and a residential site near the industrial complexes. These two sites were 5 km from each other (Figure 1). Gwangyang (34°56′N 127°41′E) is also important and large industrial cities of South Korea located in South Jeolla province of the country. This is the home of the POSCO (Pohang Steel Company), which is one of the world’s largest steel companies. This city has a population and area of approximately 150,000 and 309.4 Km, respectively (http://en.wikipedia.org/wiki/Gwangyang, accessed on July 10, 2014). The major industries located in this city are related to steel companies. In the present study, ambient air samples were collected at two sites of Gwangyang representing industrial and residential areas separated by a distance of 5 km (Figure 1).

This paper reports the measured odorous VOC and carbonyl compounds at Yeosu and Gwangyang, which are two important industrial cities of South Korea during the four seasons of 2008-2009. The concentrations of benzene and formaldehyde were also measured, even though they are not listed as odorous compounds in South Korea because of their carcinogenic nature [16, 17]. The concentrations of odorous VOC and carbonyl compounds measured at these industrial cities were also compared with those measured at Suncheon, a nonindustrial control site. The odor intensity of each VOC and carbonyl compounds was also evaluated to determine the precise odor impact of these compounds on humans. This is the first comprehensive study in Korea regarding the monitoring of VOC and carbonyl compounds in ambient air in terms of the huge number of samples and variety of odorous compounds.

2. Materials and Methods

2.1. Sampling Sites and Sampling Periods

Ambient air samples were collected for an analysis of VOC and carbonyl compounds at Yeosu Industrial (YI), Yeosu Residential (YR), Gwangyang Industrial (GI), Gwangyang Residential (GR), and Suncheon Control (SC) sties, for 10 consecutive days during spring (May 20–29), summer (August 5–14), and fall (October 17–26) of 2008 and winter (January 13–22) of 2009. At all sampling sites and for all seasons, two samples were collected manually for an analysis of carbonyl compounds for a 2 h duration and six samples were collected using an automatic continuous sampler for VOC analysis at a 4 h duration on each sampling day. On the other hand, at the YR site, only two VOC samples were collected manually per day in summer and spring and two samples per day in summer at the GR site. This is largely due to the instrumental availability during the specified period. According to the Korean Meteorological Administration (http://web.kma.go.kr/eng/index.jsp, accessed on July 10, 2014), the average temperatures observed in spring, summer, fall, and winter at Yeosu were 20.9°C, 28.2°C, 19.4°C, and 3.1°C, respectively. The mean temperatures observed in spring, summer, fall, and winter at Gwangyang were 20.5°C, 27.5°C, 17.2°C, and 2.9°C, respectively.

2.2. Sampling and Analysis of VOC and Carbonyl Compounds

Stainless steel tubes ( × 9 cm, Perkin Elmer, UK), packed with 120 mg Carbograph 2TD and 280 mg of Carbograph 1TD (40/60 mesh, Markes, UK), a low flow rate pump equipped with a mass flow controller (Flec, Chematec Inc., Denmark), and a sequential automatic tube sampler (STS 25, Perkin Elmer, UK) were used to determine the concentration of odorous VOC at the specified sites. The sampling of VOC was carried out at a flow rate of 100 mL/min for 4 h per each tube. Preconditioning of the adsorbent tubes was performed before sampling at the temperature of 250°C for 2 h with helium as the carrier gas. The performance of the adsorbent tubes used in this study was tested previously by the author’s research group [37, 38]. Table 1 lists the analytical and operating conditions for this system. The total analytical procedure followed in the analysis of VOC was described in detail in a previous research paper [39]. Table 2 lists the physical-chemical characteristics of both odorous VOC and carbonyl compounds.

Table 1: Analytical conditions for VOC with thermodesorption GC/MSD.

Thermal desorber

UNITY/ULTRA (Markes, UK)
GC/MSD

(HP6890/5973, Hewlett Packard, USA)

Oven temp.
300°C
GC column
Rtx-1 (0.32 mm, 105 m, 1.5 m)

Desorb time
10 min
Initial temp.
50°C (10 min)

Desorb flow
50 mL/min
Oven ramp rate
5°C/min

Cold trap holding time
5 min
Final temp.
250°C (5 min)

Cold trap high temp.
320°C
Post run
250°C (5 min)

Cold trap low temp.
−10°C
Column flow
1.13 mL/min

Cold trap packing
Tenax TA/carbopack B
Detector type
Quadropole

Min. pressure
12 psi
Q-pole temp.
150°C

Inlet split
No
MS Source temp.
230°C

Outlet split
10 mL/min
Mass range
35~300 amu

Valve and line temp.
180°C
Electron energy
70 eV

Table 2: Physicochemical characteristics of odor compounds in this study.

Compounds
Abb.
CAS No.
Odorous compounds
MW (g/mol)
Bp (°C)

Korea
Japan

Benzene
BZ
71-43-2
—
—
78.11
80.1

Ethyl acetate
EA
141-78-6
—
○
88.11
77.1

Methyl isobutyl ketone
MIBK
108-10-1
○
○
100.16
117.0

Toluene
TOL
108-88-3
○
○
92.14
111.0

m, p-Xylenes
mpXYLN
108-38-3

106-42-3
○
○
106.16
139.0

o-Xylene
oXYLN
95-47-6
○
○
106.17
144.4

Styrene
STR
100-42-5
○
○
104.15
145.0

Formaldehyde
FRML
50-00-0
—
—
30.03
−19.0

Acetaldehyde
ACTL
75-07-0
○
○
44.05
20.2

Propionaldehyde
PPNL
123-38-6
○
○
58.08
46.0

Methyl ethyl ketone
MEK
78-93-3
○
—
72.11
79.6

Butyraldehyde
BTL
123-72-8
○
○
72.11
74.8

i-Valeraldehyde
iVAL
590-86-3
○
○
86.13
92.0

n-Valeraldehyde
nVAL
100-62-3
○
○
86.13
102.0

For the qualitative and quantitative determination and analysis of carbonyl compounds, the calibration of carbonyl-DNPH mixture (Supelco Inc., USA) was performed with the standard working solutions diluted as 0.25, 0.5, 1.0, 3.0, and 15.0 μg/mL in the case of formaldehyde. The commercial standard mixture did not contain the methyl ethyl ketone, which was calibrated separately using an individual standard after dilution.

The sampling of carbonyl compounds was performed using DNPH cartridges (C18 Sep-Pak short-body cartridges coated with DNPH, Supelco Inc., USA). The interference of ozone during sampling was removed by connecting a polypropylene tube filled with KI (~1.4 g) at the front side of the DNPH cartridge. During sampling, a total volume of 120 L of ambient air was collected at a flow rate of 1 L/min using a sampling pump. The resulting samples were kept in a refrigerator prior to the analysis of carbonyl compounds through the solvent extraction process. The DNPH derivatives were then extracted with 4 mL of acetonitrile and the extracted solution was transferred into an amber vial (to avoid contact with sunlight), sealed tightly with Teflon tape and stored in refrigerator. All glassware used during the solvent extraction process was prewashed with acetonitrile and dried over 60°C prior to use. The extracted DNPH derivatives were analyzed by HPLC with a UV detector at 360 nm [40]. Table 3 lists all the operating conditions used in HPLC analysis of the carbonyl compounds.

Table 3: Operating conditions for the HPLC analysis of carbonyl compounds.

Operating parameter
Specifications and conditions

HPLC system
Shimadzu SCL-6B with Shimadzu SPD-6 AV UV/VIS detector at 360 nm

Analytical column
Shim-Pack CL-ODS (M) 4.6 mm × 150 mm with a C₁₈ guard column

Mobile phase
A: acetonitrile 100 (V),

B: water/acetonitrile/tetrahydrofuran 50/45/5 (v/v)

Gradient elution
100% for B for 5 min, and then 60 : 40% A : B for 15 min, finally 100% A for 50 min

Flow rate and injection volume
1.0 mL/min and 20 L injection

2.3. Quality Control and Quality Assurance

Detailed calibration process of VOC followed in this study was prescribed in a previous research paper [39]. The precision of the present method for an analysis of VOC was evaluated by the relative standard deviation (RSD) of the retention time and peak area of a known amount of VOC standard injected into each adsorbent tube. Overall, the RSDs for the peak area appeared to be <8%, whereas those for the retention time were <0.5%. The detection limit for the present method was evaluated according to the US EPA TO-17 method protocol [41] and was obtained as 0.01–0.06 ppb, depending on the individual VOC.

The repeatability of the present method was evaluated using the relative standard deviation (RSD) of the peak areas for a standard mixture (0.25 μg/mL). The RSD of the present method within a day appeared to be less than 3.5% and between days it was less than 8.0%. The detection limit for the analysis of carbonyl compounds in the present method was evaluated using the guidelines of the US EPA [42] and was obtained as 1.1~2.3 ng/mL, which is equal to 0.01~0.02 ppb (as the concentration in the air based on the total volume of 120 L). The accuracy of the present analytical method was tested by an interlaboratory comparison of the analytical data of the concentrations of carbonyl compounds. For an interlaboratory comparison, 90 carbonyl samples were taken in random and analyzed in the author’s laboratory (Yeungnam University, Korea) and another laboratory (Suncheon College, Korea). Figure 2 shows the concentrations of both formaldehyde and acetaldehyde during interlaboratory analysis which is a similar trend for all samples in two laboratories. Table 4 lists the statistical parameters of the interlaboratory comparison, which indicates an excellent correlation between the data obtained in the two laboratories.

Table 4: Interlaboratory comparison of the concentration of same carbonyl compounds analyzed at author’s laboratory (Yeungnam University, YNU) and another laboratory (Suncheon College, SCC).

Compounds
Sample number
MDP⁽¹⁾ (%)
MRE I⁽²⁾ (%)
MRE II⁽³⁾ (%)
(4)
-test ( value)
Paired -test ( value)

Formaldehyde
90
27.8
23.9
37.8
0.94*(5)
0.2
0

Acetaldehyde
90
18.5
15.3
25.6
0.97*
0.46
0

MDP (mean duplicate precision, %) = (%).

(2)MRE I (mean relative error, %) = (%).

(3)MRE II (mean relative error, %) = (%).

(4): correlation coefficient.

(5)*Correlation coefficients are significant at a level of 0.05.

Figure 2: Concentrations of formaldehyde and acetaldehyde obtained during the analysis at Yeungnam University and Suncheon College (interlab comparison).

3. Results and Discussion

3.1. Occurrence and Distribution of VOC and Carbonyl Compounds

Table 5 lists the detection frequencies and the mean, median, minimum, and maximum concentrations of the odorous VOC measured at Yeosu Industrial (YI), Yeosu Residential (YR), Gwangyang Industrial (GI), Gwangyang Residential (GR), and Suncheon Control (SC) sites. Benzene, toluene, and m,p,o-xylenes were found with detection frequencies in the range from 95 to 100% at all sites. With the exception of the YI site, styrene and methyl isobutyl ketone were found at detection frequencies below 30% and 9%, respectively, at all other sites. Overall, at Yeosu industrial site, all the VOC were observed at higher detection frequencies than the other sites. From Table 5, it is clear that the most abundant odorous VOC found at all these sites was toluene followed by m,p,o-xylenes. In addition to odorous VOC, benzene, the most important and carcinogenic VOC, was found at higher levels at all these sites than in any other VOC measured. The national air quality standard for benzene, as an annual average concentration, was established as 1.5 ppb, in Korea. The concentration of benzene was found to be higher than the Korean standard level at the industrial sites (YI and GI) and lower at the residential areas (YR and GR) and control site (SC). Regarding the odorous VOC, the least abundant compounds were methyl isobutyl ketone and styrene.

Table 5: Statistical summaries of the VOC at different sites in the present study.

Sites
VOC
Detection frequency
Mean (ppb)
S.D. (ppb)
Median (ppb)
Min (ppb)
Max (ppb)

YI

()
Ethyl acetate
79%
0.39
1.29
0.11
N.D.
16.75

Benzene
100%
3.65
6.86
1.75
0.14
38.31

Methyl isobutyl ketone
26%
0.11
0.23
N.D.
N.D.
1.46

Toluene
100%
3.25
4.40
2.01
0.06
38.61

m, p-Xylenes
100%
2.50
3.57
1.17
0.06
25.61

Styrene
48%
0.25
0.44
N.D.
N.D.
4.07

o-Xylene
100%
0.58
0.65
0.34
0.02
4.47

YR

()
Ethyl acetate
76%
0.11
0.12
0.07
N.D.
0.49

Benzene
100%
1.07
1.02
0.75
0.04
5.93

Methyl isobutyl ketone
9%
0.01
0.04
N.D.
N.D.
0.23

Toluene
100%
1.61
2.09
0.98
0.05
17.41

m, p-Xylenes
99%
0.36
0.35
0.20
N.D.
1.71

Styrene
29%
0.15
0.34
N.D.
N.D.
1.82

o-Xylene
98%
0.10
0.09
0.07
N.D.
0.47

GI

()
Ethyl acetate
62%
0.12
0.22
0.05
N.D.
1.64

Benzene
100%
1.64
3.83
0.40
0.06
27.12

Methyl isobutyl ketone
6%
0.01
0.05
N.D.
N.D.
0.37

Toluene
100%
0.97
0.87
0.75
0.04
8.45

m, p-Xylenes
99%
1.09
5.78
0.28
N.D.
27.36

Styrene
4%
0.01
0.05
N.D.
N.D.
0.46

o-Xylene
97%
0.28
1.22
0.08
N.D.
16.06

GR

()
Ethyl acetate
73%
0.10
0.13
0.06
N.D.
0.83

Benzene
100%
0.59
0.72
0.40
0.07
6.66

Methyl isobutyl ketone
3%
<0.01
0.03
N.D.
N.D.
0.29

Toluene
100%
0.98
0.77
0.78
0.01
4.10

m, p-Xylenes
98%
0.37
0.36
0.23
N.D.
2.43

Styrene
2%
<0.01
0.02
N.D.
N.D.
0.27

o-Xylene
95%
0.11
0.10
0.08
N.D.
0.52

SC

()
Ethyl acetate
53%
0.07
0.11
0.03
N.D.
1.11

Benzene
100%
0.38
0.25
0.33
0.04
2.11

Methyl isobutyl ketone
1%
<0.01
0.01
N.D.
N.D.
0.12

Toluene
100%
0.68
0.60
0.52
0.01
5.02

m, p-Xylenes
97%
0.20
0.19
0.17
N.D.
1.34

Styrene
0%
<0.01
0.01
N.D.
N.D.
0.12

o-Xylene
87%
0.06
0.06
0.05
N.D.
0.36

N.D.: not detected.

Table 6 lists the detection frequencies and the mean, median, minimum, and maximum level concentrations of odorous carbonyl compounds measured at YI, YR, GI, GR, and SC sites. Formaldehyde and acetaldehyde were found at higher detection frequencies (96–100%) at all sites followed by methyl ethyl ketone (73–91%). The compounds, such as butyraldehyde, i-valeraldehyde, and n-valeraldehyde, were detected with the lowest frequencies at all sites. Regarding the concentrations of odorous carbonyls, acetaldehyde, methyl ethyl ketone, and propionaldehyde were found to be higher in all sampling sites than the others. On the other hand, the concentration of formaldehyde found was higher than any other carbonyl compound at all sites. Butyraldehyde, i-valeraldehyde, and n-valeraldehyde were observed at lower concentrations at all sites.

Table 6: Statistical summaries of carbonyl compounds at different sites of the present study.

Sites
Carbonyl compounds
Detection frequency
Mean (ppb)
S.D. (ppb)
Median (ppb)
Min (ppb)
Max (ppb)

YI

()
Formaldehyde
96%
7.40
5.74
4.81
N.D.
26.93

Acetaldehyde
96%
2.75
2.02
2.24
N.D.
9.89

Propionaldehyde
60%
0.29
0.40
0.18
N.D.
2.67

Methyl ethyl ketone
74%
2.57
3.73
1.06
N.D.
15.92

Butyraldehyde
5%
0.06
0.34
N.D.
N.D.
2.67

i-Valeraldehyde
11%
0.03
0.09
N.D.
N.D.
0.50

n-Valeraldehyde
31%
0.11
0.22
N.D.
N.D.
0.95

YR

()
Formaldehyde
99%
8.06
6.27
5.88
N.D.
31.38

Acetaldehyde
97%
3.43
3.05
2.10
N.D.
15.74

Propionaldehyde
50%
0.35
0.61
0.06
N.D.
2.97

Methyl ethyl ketone
73%
2.05
2.93
0.96
N.D.
13.73

Butyraldehyde
29%
0.56
1.25
N.D.
N.D.
6.08

i-Valeraldehyde
12%
0.03
0.10
N.D.
N.D.
0.46

n-Valeraldehyde
26%
0.05
0.11
N.D.
N.D.
0.48

GI

()
Formaldehyde
99%
5.99
4.55
4.89
N.D.
30.52

Acetaldehyde
99%
1.97
1.12
1.85
N.D.
5.35

Propionaldehyde
44%
0.14
0.18
N.D.
N.D.
0.64

Methyl ethyl ketone
91%
2.74
3.12
2.04
N.D.
20.56

Butyraldehyde
4%
0.02
0.08
N.D.
N.D.
0.51

i-Valeraldehyde
8%
0.02
0.06
N.D.
N.D.
0.39

n-Valeraldehyde
28%
0.07
0.13
N.D.
N.D.
0.54

GR

()
Formaldehyde
100%
7.15
5.54
5.45
1.65
28.66

Acetaldehyde
100%
2.23
1.68
1.86
0.13
12.44

Propionaldehyde
34%
0.17
0.47
N.D.
N.D.
3.92

Methyl ethyl ketone
86%
2.29
3.02
1.86
N.D.
22.34

Butyraldehyde
1%
0.01
0.05
N.D.
N.D.
0.44

i-Valeraldehyde
4%
0.01
0.06
N.D.
N.D.
0.40

n-Valeraldehyde
11%
0.03
0.08
N.D.
N.D.
0.37

SC

()
Formaldehyde
98%
6.52
4.84
5.30
N.D.
25.81

Acetaldehyde
98%
2.54
2.87
1.48
N.D.
18.38

Propionaldehyde
38%
0.21
0.43
N.D.
N.D.
2.91

Methyl ethyl ketone
78%
2.05
2.11
1.75
N.D.
8.59

Butyraldehyde
10%
0.10
0.43
N.D.
N.D.
2.77

i-Valeraldehyde
5%
0.03
0.15
N.D.
N.D.
0.84

n-Valeraldehyde
18%
0.05
0.12
N.D.
N.D.
0.58

N.D.: not detected.

3.2. Spatial Distribution of VOC and Carbonyl Compounds

Figures 3 and 4 present the cumulative probabilities of distributions of the concentrations of the VOC and carbonyl compounds measured at all five sites (YI, YR, GI, GR, and SC). All the measured VOC showed higher levels at the Yeosu Industrial (YI) site and lower levels at the control site (SC) compared to the other sites. Benzene and m,p-xylenes were observed to be higher at the industrial sites (YI and GI) than the residential sites. Toluene and styrene showed higher levels at the Yeosu industrial and residential sites than the other sites. The concentration of benzene at YI site was almost 2–9 times higher than the other sites. Regarding carbonyl compounds, a few of them were higher at the residential site (YR) than at the other sites. Carbonyl compounds are not only emitted from primary sources but also formed by photochemical reactions in the atmosphere (secondary sources). This might explain the higher concentrations of few carbonyls at residential sites than the industrial sites. The residential areas were affected from the emissions of industrial and traffic sources.

Figure 3: Cumulative probability of the distributions of the concentrations of VOC.

Figure 4: Cumulative probability of distributions of the concentrations of carbonyl compounds.

3.3. Seasonal Variations in Concentrations of VOC and Carbonyl Compounds

To understand the seasonal influence on the concentrations of VOC and carbonyl compounds, their concentrations were measured during four seasons of the year and are shown in Figures 5 and 6, respectively. From this study, the concentrations of VOC and carbonyl compounds were not much influenced by the seasons. Owing to multisources and secondary reactions in the atmosphere, the concentrations of these compounds did not show constant variations in different seasons.

Figure 5: Seasonal variations of concentrations of VOC.

Figure 6: Seasonal variations of the concentrations of carbonyl compounds.

3.4. Odor Intensity of VOC and Carbonyl Compounds

Most researchers measured the concentrations of the VOC and carbonyl compounds in ambient air. On the other hand, the concentrations may not indicate their precise impact on the people’s health, particularly odorous compounds. A new parameter, odor intensity, was introduced to evaluate the accurate odor impact on people when they perceived these compounds. The odor intensity of a compound can be calculated by dividing the target analyte concentration with the standard (reference) odor intensity value of that compound. The reference values were taken from the Japanese Odor Control Law (http://www.env.go.jp/en/laws/air/odor/opm.html, accessed on July 10, 2014) to calculate the odor intensities of the VOC and carbonyls. Figures 7(a), 7(b), 7(c), 7(d), and 7(e) show the concentrations and odor intensities of odorous compounds measured at the YI, YR, GI, GR, and SC sites, respectively. In an odor intensity point of view, the maximum intensity is more significant than the mean or median value. From these figures, toluene, xylenes, acetaldehyde, and methyl ethyl ketone were found in higher concentrations, and butyraldehyde, i-valeraldehyde, and n-valeraldehyde were found at lower concentrations at most sites. Regarding the odor intensity; however, the compounds found at lower concentrations (butyraldehyde, i-valeraldehyde, and n-valeraldehyde) had more odor impact than the compounds with higher concentrations. In the case of acetaldehyde, both the concentrations and odor intensity were high.

(a)

(b)

(c)

(d)

(e)

Figure 7: (a) Concentration and odor intensity of the odor compounds at YI site. (b) Concentration and odor intensity of the odor compounds at YR site. (c) Concentration and odor intensity of the odor compounds at GI site. (d) Concentration and odor intensity of the odor compounds at GR site. (e) Concentration and odor intensity of the odor compounds at SC site.

3.5. Correlations of the VOC, Carbonyl Compounds, and Air Quality/Meteorological Data

Pearson correlation analysis was performed to examine the factors affecting the concentrations of VOC and carbonyl compounds at the study areas. Tables 7(a) and 7(b) list the correlation coefficients among the VOC and VOC to the other criteria air pollutants and meteorological conditions. In the case of VOC, aromatic VOC, such as, toluene, m,p-xylenes, and o-xylene, were correlated with each other and indicated a common source. The meteorological conditions, such as temperature and wind speed, showed a low correlation with the VOC indicating that they do not affect the concentrations of VOC at specified sites. Benzene showed a good correlation with CO at the residential sites (0.592 and 0.448 at YR and GR, resp.), indicating that combustion is a major of benzene. Similarly NO₂ and SO₂ showed a good correlation with aromatic VOC, suggesting that the fossil fuel combustion and other combustion processes in industries were the major sources of these compounds.

Table 7: (a) Pearson correlation coefficients between the different VOC. (b) Pearson correlation coefficients between VOC and other air quality parameters.

(a)

Sites
Compounds
Benzene
Ethyl acetate
MIBK
Toluene
m, p-Xylenes
Styrene

YI
Ethyl acetate
0.053

MIBK
0.317*
0.059

Toluene
0.545*
0.070
0.581*

m, p-Xylenes
0.532*
0.155*
0.753*
0.692*

Styrene
0.278*
0.051
0.267*
0.408*
0.396*

o-Xylene
0.410*
0.084
0.773*
0.644*
0.857*
0.430*

YR
Ethyl acetate
0.262*

MIBK
0.114
0.402*

Toluene
0.278*
0.178*
0.284*

m, p-Xylenes
0.380*
0.601*
0.475*
0.212*

Styrene
0.367*
0.256*
0.329*
0.425*
0.302*

o-Xylene
0.385*
0.644*
0.445*
0.269*
0.949*
0.349*

GI
Ethyl acetate
0.027

MIBK
−0.016
0.220*

Toluene
0.413*
0.187*
0.391*

m, p-Xylenes
0.032
−0.031
0.300*
0.638*

Styrene
−0.006
−0.011
0.327*
0.450*
0.454*

o-Xylene
0.027
−0.028
0.293*
0.646*
0.986*
0.458*

GR
Ethyl acetate
0.201*

MIBK
0.143*
0.285*

Toluene
0.416*
0.490*
0.343*

m, p-Xylenes
0.466*
0.449*
0.329*
0.677*

Styrene
0.159*
0.011
−0.019
0.219*
0.224*

o-Xylene
0.473*
0.466*
0.288*
0.651*
0.953*
0.192*

SC
Ethyl acetate
0.271*

MIBK
0.159*
0.193*

Toluene
0.645*
0.217*
0.230*

m, p-Xylenes
0.500*
0.256*
0.131*
0.735*

Styrene
0.158*
0.024
0.706*
0.241*
0.117

o-Xylene
0.511*
0.310*
0.190*
0.718*
0.978*
0.151*

Correlation coefficients are significant at a level of 0.05.

(b)

Sites
Compounds
SO₂
PM₁₀
O₃
NO₂
CO
Temp. (°C)
Wind speed (m/s)

YI
Benzene
−0.074
0.130*
−0.294**
0.253*
0.156*
−0.144*
−0.214*

Ethyl acetate
−0.048
0.144*
0.052
0.081
−0.057
0.079
−0.109

MIBK
0.101
0.162*
−0.027
0.367*
−0.064
0.063
−0.266*

Toluene
0.053
0.254*
−0.077
0.463*
0.024
0.048
−0.297*

m, p-Xylenes
0.030
0.235*
−0.121
0.377*
−0.038
0.063
−0.297*

Styrene
0.196*
0.188*
−0.239**
0.199*
−0.022
0.223*
−0.253*

o-Xylene
0.048
0.140*
−0.127
0.302*
−0.079
0.191*
−0.330*

YR
Benzene
0.187*
0.317*
−0.424*
0.461*
0.592*
−0.370*
0.053

Ethyl acetate
0.412*
0.341*
−0.370*
0.462*
0.290*
−0.060
−0.289*

MIBK
0.333*
0.133
−0.207*
0.280*
0.081
0.022
−0.063

Toluene
0.013
0.141
−0.220*
0.217*
0.166*
−0.087
0.098

m, p-Xylenes
0.589*
0.322*
−0.473*
0.552*
0.428*
0.003
−0.373*

Styrene
−0.013
0.093
−0.287*
0.316*
0.351*
−0.112
−0.069

o-Xylene
0.516*
0.323*
−0.468*
0.542*
0.373*
0.011
−0.362*

GI
Benzene
0.586*
0.367*
0.098
0.385*
0.070
0.213*
−0.069

Ethyl acetate
0.186*
0.151*
0.144*
0.195*
0.155*
0.020
−0.031

MIBK
0.106
0.176*
−0.156*
0.228*
0.357*
−0.122
−0.031

Toluene
0.316*
0.302*
−0.047
0.375*
0.122
0.154*
−0.035

m, p-Xylenes
0.019
0.057
−0.076
0.061
0.105
−0.057
0.027

Styrene
0.063
0.123
−0.078
0.154*
0.164*
−0.047
0.011

o-Xylene
0.021
0.060
−0.082
0.074
0.120
−0.074
0.042

GR
Benzene
0.504*
0.423*
−0.112
0.558*
0.448*
−0.017
−0.185*

Ethyl acetate
0.311*
0.334*
−0.105
0.384*
0.249*
−0.048
−0.206*

MIBK
0.265*
0.173*
−0.141*
0.275*
0.241*
−0.056
−0.060

Toluene
0.521*
0.360*
−0.137
0.566*
0.480*
0.016
−0.315*

m, p-Xylenes
0.430*
0.362*
−0.483*
0.672*
0.591*
−0.199*
−0.355*

Styrene
0.107
0.053
−0.053
0.150*
0.131
−0.056
−0.090

o-Xylene
0.384*
0.402*
−0.517*
0.699*
0.584*
−0.192*
−0.369*

SC
Benzene
0.545*
0.512*
−0.086
0.430*
0.426*
−0.108
−0.080

Ethyl acetate
0.218*
0.249*
0.013
0.172*
0.175*
−0.069
−0.007

MIBK
0.177*
0.063
−0.034
0.068
0.106
−0.075
−0.011

Toluene
0.267*
0.173*
−0.188*
0.274*
0.218*
−0.006
−0.158*

m, p-Xylenes
0.117
0.129*
−0.262*
0.325*
0.126
0.190*
−0.367*

Styrene
0.082
0.061
−0.020
0.046
0.118
−0.056
−0.010

o-Xylene
0.127*
0.163*
−0.241*
0.332*
0.119
0.228*
−0.361*

Correlation coefficients are significant at a level of 0.05.

Tables 8(a) and 8(b) present the correlation coefficients among carbonyl compounds and carbonyls with other criteria air pollutants and meteorological conditions. The correlations between the carbonyl compounds and to the combustion related compounds, such NO₂, SO₂, and CO, did not show any significant relationships among them, indicating that most of the carbonyl compounds came from fugitive emissions and not from combustion. In the formaldehyde case, it was well correlated with ozone during summer at four sites (0.648, 0.401, 0.481, and 0.709 at YI, YR, GI, and GR, resp.), suggesting that formaldehyde was produced by secondary photochemical reactions, such as ozone [43]. The meteorological conditions were not correlated or negatively correlated with the carbonyls, indicating that the concentrations of carbonyls were unaffected by the seasonal influence. The concentrations of VOC were affected by the wind direction while the same pattern was not observed in case of carbonyls. The concentrations of VOC were affected by the wind direction while the same pattern was not observed in case of carbonyls. The sources of odorous carbonyls seem to be much complex than VOC, and we estimated that they were mostly emitted by local sources and oxidation of primary pollutants (as an example, acetaldehyde from alcohols). In this respect, it is an important task to find out the local sources of carbonyls. At present we do not have much information about the local sources of carbonyls at specified study sites.

Table 8: (a) Pearson correlation coefficients between different carbonyl compounds. (b) Pearson correlation coefficients between carbonyl compounds and other air quality parameters.

(a)

Sites
Compounds
FRML
ACTL
PPNL
MEK
BTL
iVAL

YI
ACTL
0.838*

PPNL
0.356*
0.455*

MEK
0.507*
0.320*
−0.151

BTL
0.144
0.274*
0.164
−0.061

iVAL
0.099
0.074
0.155
0.077
−0.053

VAL
0.074
0.148
0.149
0.168
−0.063
−0.039

YR
ACTL
0.821*

PPNL
0.638*
0.796*

MEK
0.363*
0.209
0.061

BTL
0.287*
0.205
0.096
−0.014

iVAL
0.328*
0.287*
0.385*
0.385*
−0.069

VAL
0.397*
0.301*
0.032
−0.009
0.340*
0.189

GI
ACTL
0.428*

PPNL
0.266*
0.485*

MEK
0.064
0.022
−0.063

BTL
0.439*
0.293*
0.041
−0.081

iVAL
0.011
0.050
0.001
0.356*
0.120

VAL
0.271*
0.141
0.303*
0.389*
−0.102
0.245*

GR
ACTL
0.584*

PPNL
0.452*
0.697*

MEK
0.088
0.001
−0.057

BTL
−0.028
0.004
−0.040
0.020

iVAL
0.040
0.045
−0.046
0.029
−0.021

VAL
0.123
0.095
0.059
0.057
−0.039
0.179

SC
ACTL
0.271*

PPNL
0.120
0.713*

MEK
0.425*
0.251*
−0.123

BTL
−0.066
−0.113
−0.091
−0.171

iVAL
−0.054
0.426*
0.166
0.091
−0.042

VAL
0.122
−0.118
0.004
−0.229*
0.044
−0.088

Correlation coefficients are significant at a level of 0.05.

FRML: formaldehyde; ACTL: acetaldehyde; PPNL: propionaldehyde; MEK: methyl ethyl ketone; BTL: butyraldehyde.

iVAL: i-valeraldehyde; VAL: n-valeraldehyde.

(b)

Sites
Compounds
SO₂
PM₁₀
O₃
NO₂
CO
Temp (°C)
Wind speed (m/s)

YI
FRML
0.225*
0.298*
0.532*
0.016
−0.175
0.276*
−0.160

ACTL
0.448*
0.365*
0.279*
0.230*
0.093
0.021
−0.072

PPNL
0.345*
0.076
0.053
0.168
0.126
0.051
−0.074

MEK
−0.089
0.139
0.237*
−0.023
−0.176
0.134
−0.267*

BTL
0.575*
0.167
0.130
−0.019
−0.007
0.014
0.236*

iVAL
−0.016
0.014
0.275*
−0.125
−0.019
0.090
0.046

VAL
−0.012
0.099
−0.049
0.072
0.110
−0.239*
0.049

YR
FRML
0.096
0.509*
0.115
0.498*
0.185
0.151
−0.246*

ACTL
0.143
0.581*
−0.112
0.714*
0.402*
−0.102
−0.247*

PPNL
0.084
0.337*
−0.099
0.497*
0.275*
−0.079
−0.251*

MEK
0.162
0.169
−0.221
0.086
0.100
0.004
−0.097

BTL
−0.105
0.227*
0.144
0.100
−0.038
0.101
0.220

iVAL
0.033
0.062
−0.157
0.090
0.084
0.055
−0.173

VAL
0.035
0.297*
0.107
0.209
0.049
0.251*
−0.172

GI
FRML
0.033
0.118
0.279*
0.126
−0.049
0.362*
−0.127

ACTL
0.261*
0.410*
0.058
0.525*
0.332*
0.249*
−0.303*

PPNL
0.139
0.091
0.194
0.169
0.026
0.528**
0.000

MEK
−0.247*
−0.062
−0.195
−0.195
−0.073
0.132
−0.030

BTL
0.039
0.051
0.155
0.176
−0.049
0.116
−0.041

iVAL
−0.063
0.119
−0.028
0.038
−0.004
0.066
−0.087

VAL
−0.163
0.039
−0.015
−0.128
−0.150
0.312*
0.021

GR
FRML
−0.004
0.161
0.180
0.100
0.027
0.248*
−0.197

ACTL
0.258*
0.505*
0.044
0.478*
0.360*
0.114
−0.392*

PPNL
0.004
0.072
0.141
0.069
0.007
0.200
−0.174

MEK
0.042
0.067
−0.218
0.072
0.084
0.056
−0.079

BTL
−0.081
−0.021
−0.048
−0.096
−0.072
−0.024
−0.064

iVAL
0.052
0.205
0.089
0.095
−0.004
0.129
−0.072

VAL
0.075
0.035
0.110
−0.037
0.057
0.329*
−0.072

SC
FRML
0.347*
0.414*
0.015
0.460*
0.377*
0.138
−0.378*

ACTL
0.295*
0.327*
−0.109
0.466*
0.348*
−0.057
−0.405*

PPNL
0.292*
0.223*
−0.133
0.263*
0.155
−0.127
−0.244*

MEK
0.267*
0.465*
−0.063
0.488*
0.590*
−0.231*
−0.277*

BTL
−0.135
−0.061
0.075
−0.138
−0.155
0.116
0.097

iVAL
0.058
0.025
−0.283*
0.252*
0.300*
−0.175
−0.237*

VAL
−0.162
−0.120
0.189
−0.196
−0.198
0.396*
0.026

Correlation coefficients are significant at a level of 0.05.

FRML: formaldehyde; ACTL: acetaldehyde; PPNL: propionaldehyde; MEK: methyl ethyl ketone; BTL: butyraldehyde.

iVAL: i-valeraldehyde; VAL: n-valeraldehyde.

3.6. Comparison of the Concentrations of VOC and Carbonyl Compounds of the Present Study with the Others Reported Worldwide

The concentrations of VOC and carbonyl compounds measured in this study were compared with those of other cities in the world and are presented in Tables 9 and 10, respectively. For this purpose, present data was compared with other data measured mainly at industrial and residential sites. The concentration of benzene found in Yeosu Petrochemical Industrial Site is lower than that reported for other petrochemical industrial sites at Mumbai (India) and Kaohsiung (Taiwan) and higher than those reported for Dunkerque (France), Rem-Wu (Taiwan), and Yokohoma (Japan). On the other hand, the benzene concentration found at Gwangyang Steel Industrial Site was lower than that of most steel industrial sites compared except for the Pohang (South Korea) Steel Industrial Site. The toluene to benzene ratio (T : B) found in the present study was in the range of 0.59–1.79.

Table 9: Comparison of the concentrations (ppb) of VOC reported in present method with other cities in the world.

S. No.
City/country
Sampling period
Site characteristics

Analysis
BZ
TOL
XYLN
MIBK
EA
STR
T/B ratio
Reference

1
Pohang/Korea*
Jan, 2006–Feb, 2009
Steel, Ferro-alloy industries
—
On-line TD/GC-FID
0.12
0.18
0.13
—
—
0.34
1.50
[18]

Residential
0.78
2.50
0.66
—
—
0.14
3.21

2
Yokohoma/Japan
June 2007–Nov, 2008
Petrochemical industries
69
GC-FID
0.70~2.10
1.60~5.20
0.40~2.10
—
0.40~0.60
—
—
[19]

Residential
0.40~0.90
1.90~2.20
0.20~0.70
—
0.60
—
—

3
Tzouying/Taiwan
Oct-Nov, 2004
Oil refinery
24
GC-MS
1.6~2.5
24.5~42.00
1.5~2.10
—
—
—
—
[20]

4
Kaohsiung/Taiwan
July and Oct, 2003
Petrochemical industrial park (Rush hours)
—
GC-MS
11.29
160.88
22.07
—
—
15.16
14.25
[21]

Nonrush hours

13.49
101.99
15.15
—
—
—
7.56

5
Southern Taiwan, Ping-Nan IP
July, 2003–Dec, 2004
Iron and steel industries
129
GC-FID
1.98
4.33
3.72
—
—
—
2.18
[22]

Rem-Wu IP
Petrochemical and general manufacturing industries
1.99
14.52
7.14
—
—
—
7.29

Naan-Zi IP
Petroleum and petrochemical industries
2.17
5.41
4.95
—
—
—
2.49

6
Shanghai/China
Jan, 2007–Mar, 2010
Chemical and steel industries
284
GC-MS
1.81
4.70
1.89
—
2.09
0.14
2.59
[23]

7
Mumbai/India*
2004
Petrochemical, pharma, and plastic industries
—
TD/GC-MS
0.62
1.47
0.02
—
—
0.03
2.37
[24]

8
Mumbai/India*
May 2001–Apr, 2002
Petrochemical industries
24
TD/GC-MS
60.98
20.42
0.03
—
—
—
0.33
[25]

Residential
13.71
7.48
0.25
—
—
—
0.55

9
Dunkerque/France*
July–Sep, 2009
Petrochemical, chemical, and steel industries
—
GC-FID
0.12
0.31
0.19
—
—
0.03
2.58
[26]

10
Dunkerque/France*
Jan, 2007
Petrochemical, chemical, and steel industries
—
TD/GC-FID
0.58
2.59
0.63
—
—
—
4.46
[27]

June, 2007
0.47
0.54
0.18
—
—
—
1.14

11
Seoul/Korea
Feb–Jul, 2009
Urban residential
18
GC-MS
0.58
5.39
1.16
—
—
0.45
9.29
[28]

12
Yeosu industrial/Korea
May, Aug, Oct 2008, Jan 2009
Oil refinery and [petrochemical industries
234
TD/GC-MS
3.65
3.25
3.08
0.11
0.39
0.25
0.89
this study

Yeosu residential/Korea
Residential
160
TD/GC-MS
1.07
1.61
0.46
0.01
0.11
0.15
1.50

Gwangyang industrial/Korea
Steel industries
239
TD/GC-MS
1.64
0.97
1.37
0.01
0.12
0.01
0.59

Gwangyang residential/Korea
Residential
199
TD/GC-MS
0.59
0.98
0.48
<0.01
0.10
<0.01
1.66

Suncheon comparison/Korea
Residential
240
TD/GC-MS
0.38
0.68
0.26
<0.01
0.07
<0.01
1.79

: no. of data; TD: thermal desorption; BZ: benzene; TOL: toluene; XYLN: m, p, o-xylenes; STR: styrene; EA: ethyl acetate; STR: styrene; IP: industrial park.*Concentration of VOC is reported by those authors in g/m³ and in present table they are converted into ppb (at 15°C).

Table 10: Comparison of the concentrations of carbonyl compounds reported in present method with other cities in the world.

S. No.
City/country
Sampling period
Site characteristics

FRML
ACTL
PPNL
BTL
iVAL
nVAL
MEK

Reference

1
Kolkata/India
Site 1, summer
Mixed (res., traffic, and ind.)
—
18.60
9.09
1.50
1.46
—
—
—
2.0
[29]

Winter

13.76
6.76
1.02
0.75
—
—
—
2.0

Site 2, summer
Mixed (res., traffic, and ind.)

11.02
4.59
0.73
1.30
—
—
—
2.4

Winter

9.92
4.98
0.95
0.74
—
—
—
2.0

2
Guangzhou/China
July–Sep, 2003
Residential
5
10.88
5.83
1.11
0.66
0.23
0.25

1.9
[30]

Industrial
5
11.07
3.96
0.55
0.29
0.08
0.62

2.8

3
Guangzhou/China
17–19, Nov–2005

(clear days)
Residential and traffic site
12
4.74
3.95
0.35
0.78
0.12
0.16

1.2
[31]

30 Nov–2, Dec 2005

(hazy days)
Residential and traffic
12
11.49
8.91
1.16
0.81
0.18
2.74

1.3

4
Ansan, Shi Hung/Republic of Korea
Aug, 2004–Sep, 2005
Industrial
—
19.30
19.50
19.00
13.00
0.93
0.82

1.0
[8]

5
Gumi/Republic of Korea
Dec, 2003–Nov, 2004
Industrial site 1
172
3.40
7.35
0.80

2.40
0.5
[6]

2004
Industrial site 2
78
3.87
2.52
1.01

4.81
1.5

2004
Industrial, site 3
77
3.86
4.22
1.04

3.32
0.9

6
Mexico city/Mexico
Mar,1998–Feb, 1999
Mixed (res., com., and ind.)
35
4.33
2.31
0.53
0.29
0.44
0.16

1.9
[32]

7
Rome/Italy
2006
Urban
—
2.16
1.26
0.41
1.61
0.06
0.13

1.7
[33]

8
Kurkimaki/Finland
—
Residential
—
0.37
0.36
0.05
0.03

1.0
[34]

9
Roverdo
Nov-Dec, 2005
Rural
—
—
0.38
0.10
0.05

0.08
—
[35]

Zurich/Switzerland
Nov-Dec, 2005
Urban res.
—
—
0.86
0.12
0.04

0.03
—

10
Santiago/Chile
Nov-Dec, 2003
Downtown
40
3.90
3.00
0.46
3.30
0.11

1.3
[36]

11
Yeosu industrial/Korea
May, Aug, Oct 2008, Jan 2009
Oil refinery, petrochemical industries
80
7.40
2.75
0.29
0.06
0.03
0.11
2.57
2.7
This study

Yeosu residential/Korea
Residential
78
8.06
3.43
0.35
0.56
0.03
0.05
2.05
2.3

Gwangyang industrial/Korea
Steel industries
79
5.99
1.97
0.14
0.02
0.02
0.07
2.74
3.0

Gwangyang residential/Korea
Residential
80
7.15
2.23
0.17
0.01
0.01
0.03
2.29
3.2

Suncheon comparison/Korea
Residential
80
6.52
2.54
0.21
0.10
0.03
0.05
2.05
2.6

The concentration of formaldehyde (group 1 carcinogen) reported in the present study was lower than that reported at Kolkata (India), Guangzhou (China), and Ansan (South Korea), and higher than at Gumi (South Korea), Rome (Italy), and Mexico City (Mexico). Most researchers worldwide reported very low concentrations of i-valeraldehyde and i-valeraldehyde and butyraldehyde (except Ansan, South Korea). On the other hand, although they exist at low concentrations, their odor intensity was higher than other higher abundant carbonyl compounds.

3.7. Health Implications of Benzene and Formaldehyde Levels from This Study

The WHO has no standard for benzene, since benzene is known to be nonthreshold pollutant. Instead, the WHO [44] provides a unit risk for benzene, which is 6 × 10⁻⁶. This means that the life time exposure to 1 μg m⁻³ (c.a. 0.31 ppb) of benzene will cause six cases of leukemia per one million of the population. According to the present results, the mean concentration of benzene was 1.07 ppb (YR) and 0.59 (GR), which may cause six and two leukemia cases among the life-time residents in Yeosu residential area and Gwangyang residential areas, respectively. The unit risk for formaldehyde is 1.3 × 10⁻⁵. This suggests that the life time exposure to 1 μg m⁻³ (c.a. 0.79 ppb) of formaldehyde will cause one case of cancer per one million of the population. The mean concentrations of formaldehyde found in the present study were 8.06 ppb (YR), and 7.15 ppb (GR), which may cause forty and seventeen cancer cases among the life-time residents in Yeosu residential area and Gwangyang residential areas, respectively. This prediction is based solely on the concentrations of the respective compounds measured in this study and the residents of these cities if exposed for a lifetime.

4. Conclusion

This paper reported the concentrations of odorous VOC and carbonyl compounds at large industrial areas of South Korea. In this study, the levels of few carbonyls were higher in residential areas near industrial areas. This indicates the influence of industrial sources on the air quality of residential areas in close proximity. Few of the carbonyls were found to be higher in residential areas than in industrial areas; more focus on the determination of the source profiles of these particular compounds is needed. The residential areas provide some sources for these compounds and/or the secondary reactions may also be responsible. In the present study, the odor intensity of the VOC and carbonyls, which gives an accurate impact on the people when they perceived these compounds, was determined. In addition to the odorous compounds, carcinogens, such as, benzene and formaldehyde, were found to be higher at industrial sites than the Korean National Standard Level Concentrations.

Conflict of Interests

The authors declare that there is no conflict of interests regarding the publication of this paper.

Acknowledgment

This work was supported by the 2014 Yeungnam University research grant.

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