Environ Sci Pollut Res (2012) 19:201–213
DOI 10.1007/s11356-011-0550-0

RESEARCH ARTICLE

Environmental risk assessment and concentration trendof atmospheric volatile organic compounds in Hyogo
Prefecture, Japan
Yasushi Okada & Akihiro Nakagoshi &Masahiro Tsurukawa & Chisato Matsumura & Jiro Eiho &Takeshi Nakano

Received: 28 December 2010 / Accepted: 13 June 2011 / Published online: 30 June 2011
# The Author(s) 2011. This article is published with open access at Springerlink.com

Abstract
Purpose The purpose of this study was to evaluate theinfluences of volatile organic compounds (VOCs) emissions on hazardousness and photochemical reactivity and to
propose efficient VOCs abatement strategies.
Methods The atmospheric concentrations of 101 componentsof VOCs were measured at six sites which comprehend foururban areas, a roadside area, and an industrial area in Hyogo
Prefecture. VOCs influence on hazardousness and photochemical reactivity were evaluated using VOCs measured
data and the index on the health effect evaluation and ozone
formation potential. The substances that require emissions
reduction were selected from the evaluation results. The stateand characteristics of environmental pollution were considered from the concentration trends of the selected substances.
Results In industrial area, n-hexadecane, styrene, vinyl
chloride monomer, and 1,2-dichloroethane showed a highconcentration. In roadside area, n-hexane, n-undecane, n-dodecane, tetrachloroethylene, formaldehyde, acetaldehyde,
and 1-butanol showed a high concentration. The excess
cancer incidences for formaldehyde exceeded 10−5 of thelevel of concern for carcinogenic effect at all sites. Toluene
had a high percentage of ozone production. The interannual
and seasonal trends of toluene concentrations were different
at a regional level and the formaldehyde concentrations insummer were significantly higher than those in winter at theurban sites.
Conclusions The results show the need to prepare theemission reduction plan for the major sources such as
vehicle exhaust, solvent use, and industrial processes todiminish the concentration of toluene that contributes
significantly to the formation of photochemical oxidant.
Keywords VOC . Aldehyde . Ethylene oxide .
Photochemical oxidant . Risk assessment . Unit risk .
Reference concentration . MIR

Responsible editor: Euripides Stephanou
Y. Okada : A. Nakagoshi : M. Tsurukawa : C. Matsumura :J. Eiho : T. Nakano (*)
Hyogo Prefectural Institute of Environmental Sciences,
Hyogo, Japane-mail: ntakeshi@jrl.eng.osaka-u.ac.jp
Y. Okada : T. Nakano
Graduate School of Maritime Sciences, Kobe University,
Kobe, Japan
T. Nakano
National Institute for Environmental Studies,
Tsukuba, Japan
T. Nakano
Graduate School of Engineering, Osaka University,
Osaka, Japan

1 Introduction
According to the Air Pollution Control Law of Japan, avolatile organic compound (VOC) is defined as one that
becomes gas in the atmosphere. Major sources of VOCs
include vehicle exhausts, gasoline evaporation, solvent use,
natural gas emissions, and industrial processes (Friedrichand Obermeier 1999). VOCs are emitted into the atmosphere from industrial plants (Na et al. 2001; Tsai et al.
1995), vehicles (Colon et al. 2001; Notells et al. 2000), andhouseholds (Kostiainen 1995; Sack et al. 1992). VOCs
consist of more than 500 compounds with various
properties (Lewis et al. 2000). Some of them (e.g., benzene,
1,3-butadiene, and tetrachloroethylene) directly influence

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Environ Sci Pollut Res (2012) 19:201–213

human health due to their carcinogenicities, neurologicaldisorders, and so on (Jo and Song 2001; Kostiainen 1995;
Mukund et al. 1996; Sweet and Vermette 1992). They arealso important precursors of the photochemical oxidant,
which is primarily composed of ozone, peroxyacetyl nitrate,and carbonyl compounds (Atkinson 2000; Wakamatsu et al.
1996). Carbonyl compounds are one of the VOCs, andformed indirectly from VOCs as mentioned above andemitted directly from motor vehicles and incomplete
combustion of hydrocarbon fuels in industrial machineryand industrial processes (i.e., production of paper, adhesive,
automobile, etc.) (Grosjean et al. 1993, 1996, 2002; Liu etal. 2006; Moussa et al. 2006; Possanzini et al. 2002; Sin etal. 2001; Viskari et al. 2000). In addition, some of them are
irritants for skin, eyes and nasopharyngeal membranes andtoxic to human health. In particular, formaldehyde andacetaldehyde are suspected to be carcinogenic and mutagenic to humans (WHO 2000). And that is, VOCs releaseprimary (directly emitted from sources) and secondary(formed by atmospheric chemical reactions) pollutants.
Thus, VOCs are considered to comprise a very important
category of air pollutants. Furthermore, individual VOCs
significantly differ in terms of their effect on hazardousness
and photochemical reactivity (Hoshi et al. 2007). Therefore,
in order to propose efficient air pollution abatement
strategies, it is important to know the sources and behaviorof VOCs and evaluate the influence of VOCs emissions on
hazardousness and photochemical reactivity. The results ofinvestigations on the state of environmental pollution of
VOCs have been reported by many researchers (Filella andPenuelas 2006; Iovino et al. 2009; Kerbachi et al. 2006;
Laowagul and Yoshizumi 2009; Lee et al. 2002; Martins etal. 2007; McCarthy et al. 2007; Pankow et al. 2003; Parraet al. 2009; Qin et al. 2007; Wu et al. 2011). For example,
Lee et al. quantified the concentrations of VOCs at fiveurban sites. And, Pankow et al. determined the ambient air
Fig. 1 Location of samplingsites. Ambient air samples werecollected once a month for
5 years (from 2005 to 2009) at
six sites which comprehend urban areas (Sanda, Nishiwaki,
Toyooka, and Sumoto), a roadside area (Ashiya), and an industrial area (Takasago) in
Hyogo Prefecture, Japan

concentrations of 88 VOCs in samples taken at 13 semirural to urban locations. Also, Wu et al. measured 15
hazardous air pollutants including eight VOCs at six sites
for more than a year between 2000 and 2002 and further
estimated the potential health risks based on the monitored
data. However, the results of the evaluations of the influence
on both hazardousness and photochemical reactivity by using
VOCs measurements have rarely been reported. In this study,
the atmospheric concentrations of 101 components of VOCs
were measured at six sites which comprehend four urban
areas, a roadside area, and an industrial area in Hyogo
Prefecture. And, VOCs influence on hazardousness andphotochemical reactivity were evaluated using VOCs measured data and the index on the health effect evaluation andozone formation potential. Furthermore, the substances that
require emissions reduction were selected from the evaluation
results. And, the state and characteristics of environmental
pollution were considered from the concentration trends of theselected substances.

2 Materials and methods
2.1 Measuring procedure of ambient air samples
Ambient air samples were collected once a month for
5 years (from 2005 to 2009) at six sites which
comprehend urban areas (Sanda, Nishiwaki, Toyooka,
and Sumoto), a roadside area (Ashiya), and an industrial
area (Takasago) in Hyogo Prefecture, Japan. The locationof the sampling sites is shown in Fig. 1. The target
compounds for measurement were 101 components of
VOCs (31 alkanes, 12 alkenes, 18 aromatic hydrocarbons,
28 organic halogen compounds, 11 oxygenated compounds, and one nitrogenous compound). The analyticalmethods for these compounds were based on the manual

Hyogo prefectureJapan

Toyooka

Nishiwaki
Sanda
Takasago

Ashiyaurban area
roadside areaindustrial area

SumotoEnviron Sci Pollut Res (2012) 19:201–213

203

released by the Ministry of the Environment, Japan(Ministry of the Environment, Japan 2010a, b, c).
2.1.1 VOCs except aldehydes and ethylene oxide
A multi-bed sorbent tube containing graphitized carbon(Carbopack B, Sigma-Aldrich Co.) and a carbon molecularsieve (Carboxen-1000, Sigma-Aldrich Co.) was used forsampling air. A glass tube with an infill of a desiccant(magnesium perchlorate) was connected before a tube toeliminate water. An air sample was drawn through the tube
at a flow rate of 10 ml min−1 for 24 h, and VOCs wereadsorbed and collected into the tube. An analysis was
carried out using a thermal desorption system (ATD-400,
Perkin-Elmer Co.) and Gas chromatography–mass spectrometry (GC-MS; QP-5000, Shimadzu Co.). The operational conditions of the thermal desorption system were as
follows: primary desorption temperature, 300°C; primarydesorption time, 5 min; second-stage trap temperatureduring primary desorption, −20°C; second-stage trap
desorption temperature, 350°C; hold time, 15 min; sorbent
for second-stage trap, Carbopack B and Carboxen-1000.
The operational conditions of GC-MS were as follows:column, VOCOL (0.53 mm I.D.×105 m, df=3 μm, SigmaAldrich Co.); GC oven program, 0°C for 9 min, 5°C min−1
to 100°C, 15°C min−1 to 220°C, and hold time, 13 min.

2.1.2 Aldehydes
Ambient air samples were collected at five sites except
industrial area. A cartridge containing silica gel coated with
2,4-dinitrophenylhydrazine (DNPH) (Sep-Pak XPoSure Aldehyde Sampler, Waters Co.) was used for sampling air. To
prevent aldehyde breakthrough, two cartridges wereconnected in series, and an ozone scrubber (Waters Co.) wasconnected before the cartridges to prevent the interference ofozone. An air sample was drawn through the cartridge at aflow rate of 100 ml min−1 for 24 h, and aldehydes werereacted with DNPH to form a derivative within the cartridge.
After collection, aldehyde-DNPH derivatives were eluted
with 5 ml of acetonitrile. Twenty microliters of eluate wasinjected into the HPLC system (LC-VP, Shimadzu Co.)through an auto-injector. The operational conditions of
HPLC were as follows: column, Shim-pack FC-ODS(150×4.6 mm I.D., 3 μm particles, Shimadzu Co.); mobile
phase, 60:40, acetonitrile/water (in volume ratio); flow rate,
1 ml min−1; detector, UV at 360 nm.
2.1.3 Ethylene oxide
Ambient air samples were collected at four urban sites. An
adsorbent tube containing a carbon molecular sieve coatedwith hydrogen bromide (ORBO-78, Sigma-Aldrich Co.) was

Table 1 Health assessment information on measured substances
Reference concentration(μg m−3)
Vinyl chloride monomer
1,3-Butadiene
Carbon tetrachloride
Bromomethane
Isopropylbenzene
Cyclohexane
1,1-Dichloroethylene
Ethyl chloriden-Hexane
Methyl chloride
Methyl ethyl ketone
Methyl isobutyl ketone
1,1,1-Trichloroethane
Acrylonitrile

Unit riske(per μg m−3)

100a4.4×10−6

a

−5

2
100a
5a
400a
6,000a200a
10,000a700a90a
5,000a3,000a5,000a2b3.0×10
6.0×10−6
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
6.8×10−5

Dichloromethane
Chloroform
1,2-Dichloroethane
BenzeneTrichloroethylene
Tetrachloroethylene
Acetaldehyde
Formaldehyde
TolueneXyleneEthylbenzene
Styrenep-Dichlorobenzene

Reference concentration(μg m−3)

Unit riske(per μg m−3)

150c

4.7×10−7

b

18
NA
30a
200c
200c
48d
100d
260d
870d
3,800d220d
240d

NA not assessedaReference concentration for chronic inhalation exposure, Environmental Protection Agency, USAb

Guideline value for hazardous air pollutants to reduce health risks, Ministry of the Environment, Japanc

Environmental quality standard (air quality), Ministry of the Environment, Japand

Guideline value for indoor air concentration, Ministry of Health, Labour and Welfare, Japane

Quantitative estimate of carcinogenic risk from inhalation exposure, Environmental Protection Agency, USA

2.3×10−5
2.6×10−5
2.2–7.8×10−6
NANA
2.2×10−6
1.3×10−5
NA
NA
NA
NA
NA

204

Environ Sci Pollut Res (2012) 19:201–213

In the case of a carcinogenic effect, the hazardousness of
VOCs was evaluated by calculating the excess cancer
incidence (ΔR).

where UR is the inhalation unit risk (per μg m−3) and MC
is the mean concentration (μg m−3). The inhalation unit risk
is the lifetime risk of excess cancer cases predicted to occur
from continuous exposure to a compound at a concentrationof 1 μg m−3 in the air. If the excess cancer incidence ismore than or equal to 10−5, it is determined that a detailed
evaluation of the carcinogenic effect is required. Unit risk
values for each substance were taken from the Integrated
Risk Information System (IRIS) (US EPA 2010). The
substances without unit risk values were not included in
the evaluation process. Table 1 shows the unit risk values
for the measured substances. The unit risk value forbenzene is set to be in the 2.2×10−6/μg m−3 to 7.8×
10−6/μg m−3 range. In this study, 5.0×10−6/μg m−3 of amedian was used to calculate the excess cancer incidence.
In the case of a noncarcinogenic effect, the hazardousnessof VOCs was evaluated by calculating the hazard quotient(HQ).

ΔR ¼ UR  MC;

HQ ¼ MC = RfC;

used for sampling air. An air sample was drawn through thetube at a flow rate of 700 ml min−1 for 24 h, and ethyleneoxide reacted with hydrogen bromide to form 2-bromoethanol
into the tube. After collection, 2-bromoethanol was eluted
with 1 ml of a toluene-acetonitrile mixed solvent (1:1, involume ratio). One microliter of eluate was injected into GCMS (GC, 6890N, Agilent Ltd.; MS, JMS-Q1000GC K9,JEOL Ltd.) through an auto-injector. The operational conditions of GC-MS were as follows: column, SUPELCOWAX10 (0.25 mm I.D.×30 m, df=0.25 μm, Sigma-AldrichCo.); GC oven program, 40°C for 5 min, 5°C min−1 to
100°C, 20°C min−1 to 200°C, and hold time, 3 min.
2.2 Evaluation procedure on the hazardousness of VOCs

Table 2 Maximum incremental reactivity of measured substances
MIR

MIR

trans-2-Butene
cis-2-Butene

15.16
14.24

Toluene
Methyl isobutyl ketone

4.00
3.88

1,3-Butadiene
3-Chloro-1-propene
1,2,3-Trimethylbenzene
1,3,5-Trimethylbenzene
2-Methyl-1,3-butadienetrans-2-Pentene
cis-2-Pentene
1-Butene
Formaldehyde
1,2,4,5-Tetramethylbenzene
1,2,4-Trimethylbenzene
m-, p-Xylenea
o-Xylene
1-Pentene
m-Diethylbenzene
Acetaldehyde

12.61
12.22
11.97
11.76
10.61
10.56
10.38
9.73
9.46
9.26
8.87
7.80
7.64
7.21
7.10
6.54

cis-1,3-Dichloropropene
β-Pinene
Ethylbenzene
1-Butanol
Vinyl chloride monomer
Isopropylbenzene
1-Propanol
Cyclopentane
Acrylonitrile
Methylcyclopentane
n-Propylbenzene
3-Methylpentane
1,1-Dichloroethylene
Styrenecis-1,2-Dichloroethylene
Methylcyclohexane

3-,4-Ethyltoluenea
2-Ethyltoluene
2-Methyl-1-pentene
trans-1,3-Dichloropropene
Limonene
α-Pinenep-Diethylbenzene

5.92
5.59
5.26
5.03
4.55
4.51
4.43

3-Methylhexane
2,4-Dimethylpentane
Methyl ethyl ketone
Isopentane
2,3-Dimethylpentane
n-Pentane
2,2,4-Trimethylpentane

MIR

1.25
1.24

Acetone
Chlorobenzene

0.36
0.32

3.70
3.52
3.04
2.88
2.83
2.52
2.50
2.39
2.24
2.19
2.03
1.80
1.79
1.73
1.70
1.70

Cyclohexane
2,3-Dimethylbutane+
2-Methylpentanea
n-Hexane
3-Methylheptane
Isobutane
2-Methylhexane
2,2-Dimethylbutane
n-Butane
n-Heptane
2-Methylheptane
2,3,4-Trimethylpentane
n-Octane
Butyl acetate
n-NonaneBenzenen-Decane
Trichloroethylene
Ethyl acetate

1.24
1.24
1.23
1.19
1.17
1.15
1.07
1.07
1.03
0.90
0.83
0.78
0.72
0.68
0.64
0.63

Ethyl chloride
1,2-Dichloropropane
1,2-Dichloroethane
p-Dichlorobenzene
o-Dichlorobenzene
1,2-Dibromoethane
1,1,2-Trichloroethane
1,1-Dichloroethane
Methyl chloride
Dichloromethane
Ethylene oxide
Tetrachloroethylene
Bromomethane
Chloroform
1,1,1-Trichloroethane
Carbon tetrachloride

0.29
0.29
0.21
0.18
0.18
0.10
0.09
0.07
0.04
0.04
0.04
0.03
0.02
0.02
0.01
NA

1.61
1.55
1.48
1.45
1.34
1.31
1.26

n-Undecane
2-Propanoln-Dodecane
n-Tridecane
n-Tetradecane
n-Pentadecane
n-Hexadecane

0.61
0.61
0.55
0.53
0.51
0.50
0.45

1,1,2,2-Tetrachloroethanem-Dichlorobenzene
Benzyl chloride
1,2,4-Trichlorobenzene
Hexachloro-1,3-butadiene

NA
NA
NA
NA
NA

NA not assesseda

MIR

The average amount of MIR values for two substances is indicatedEnviron Sci Pollut Res (2012) 19:201–213

205

Table 3 VOCs concentrations at sampling sites (unit: μg m−3; median; n=60)
Sanda

Nishiwaki

Toyooka

SumotoAshiyaTakasago

5
3.9
1.8
4.6
0.33
4.3
0.25

4
2.1
1.3
2.2
0.13
2.3
0.042

5.7
3.5
1.4
6.2
0.15
5.5
0.085

17
10
2.3
7.4
0.16
6.5
0.12

6
3.8
3.2
8.5
0.18
8.8
0.11

5.6
3.5
2.6
6
0.15
3.7
0.15

1.3
1.7
1.2
0.02
1.5
0.17
0.13
0.81
0.99
1.2
0.38
0.29
0.49
0.24
0.46

0.46
0.62
0.53
0.02
1.6
0.072
0.066
0.74
0.59
2
0.4
0.22
0.11
0.14
0.28

1.1
0.94
1.5
0.02
1.5
0.15
0.1
0.66
0.65
1.1
1.5
0.18
0.19
0.35
0.54

1.3
1.2
1.2
0.02
1.6
0.13
0.11
1
0.87
1
0.74
0.25
0.31
0.29
0.48

1.9
1.5
1.7
0.02
0.98
0.091
0.1
0.96
0.68
0.4
0.35
0.29
0.13
0.1
0.24

1.7
1.8
0.71
0.02
2.2
0.11
0.1
1.3
1.3
1.6
0.37
0.21
0.11
0.17
0.3

0.48
2.1
1.7
2

1.5
4
2.4
2.1

2.3
2.9
3.8
2.3

0.83
2.9
4.7
5

0.57
3.8
9.2
6.5

1
2
1.8
1.4

n-Tridecanea
n-Tetradecanea
n-Pentadecane
n-Hexadecanea
Alkenes
1-Butenecis-2-Butene
trans-2-Butene
1,3-Butadiene
1-Pentene
cis-2-Pentene
trans-2-Pentene
2-Methyl-1,3-butadienea
2-Methyl-1-pentene
α-Pinene
β-Pinene
Limonene
Aromatic hydrocarbons

0.9
1.3
0.23
0.2

1.6
1.7
0.29
0.25

1.3
1.4
0.28
0.23

6.4
2.8
0.33
0.27

1.7
2.3
0.29
0.27

0.95
0.76
0.25
1.3

4.9
0.54
0.66
0.13
0.23
0.46
0.19
1
0.24
1
0.39
1.4

3.2
0.16
0.17
0.063
0.14
0.14
0.06
0.35
0.14
0.93
0.41
1.1

6.9
0.22
0.26
0.085
0.18
0.17
0.077
0.36
0.22
1.1
0.41
1.1

6.6
0.39
0.5
0.14
0.28
0.33
0.19
0.46
0.25
0.44
0.4
1.5

7.5
0.32
0.4
0.15
0.32
0.27
0.16
0.24
0.34
0.68
0.37
0.82

4.3
0.25
0.34
0.13
0.27
0.42
0.2
0.19
0.24
0.61
0.8
0.3

BenzeneTolueneEthylbenzene
o-Xylene

1.7
18
4.6
1.5

1.3
8.7
2.9
1.2

1.3
11
6.1
1.9

2
12
8.1
2.6

1.6
13
8.1
2.3

1.5
15
4.6
1.6

Alkanesn-Butanea
Isobutanea
n-Pentane
Isopentane
Cyclopentanea
n-Hexanea
2,2-Dimethylbutane
2,3-Dimethylbutane+2-methylpentane
3-Methylpentane
Cyclohexane
Methylcyclopentaneb
n-Heptane
2,3-Dimethylpentane
2,4-Dimethylpentane
2-Methylhexane
3-Methylhexane
Methylcyclohexane
n-Octane
2,2,4-Trimethylpentane
2,3,4-Trimethylpentane
2-Methylheptane
3-Methylheptane
n-Nonanea
n-Decanen-Undecanea
n-Dodecanea

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Environ Sci Pollut Res (2012) 19:201–213

Table 3 (continued)
Sanda

Nishiwaki

Toyooka

SumotoAshiyaTakasagom-,p-Xylene
Styrenean-propylbenzene
Isopropylbenzene
2-ethyltoluene
3-,4-ethyltoluene
1,2,3-Trimethylbenzene
1,2,4-Trimethylbenzenea
1,3,5-Trimethylbenzene
m-Diethylbenzene
p-Diethylbenzene
1,2,4,5-Tetramethylbenzene

3.5
0.48
0.54
0.17
2.4
0.57
0.74
2
0.56
0.18
0.72
0.24

3.2
0.25
0.55
0.15
3
0.82
1.1
3
0.8
0.25
1
0.22

5.1
0.45
0.87
0.36
2.4
0.69
0.78
2.5
0.64
0.23
0.84
0.21

6.1
0.46
0.87
0.57
2.3
0.6
0.83
2.1
0.6
0.2
0.76
0.24

6.4
0.59
0.89
0.52
2
0.5
0.58
2.2
0.48
0.15
0.55
0.14

4.4
0.73
0.41
0.12
2.4
0.62
0.72
2.4
0.6
0.19
0.73
0.12

Organic halogen compounds
Methyl chloride
Dichloromethanea
Bromomethaneb
Chloroform
Carbon tetrachloride
Vinyl chloride monomera
Ethyl chloride
1,1-Dichloroethylenea
cis-1,2-Dichloroethylenec
1,1-Dichloroethanec
1,2-Dichloroethanea
Trichloroethylene
1,1,1-Trichloroethanea
1,1,2-Trichloroethanec
Tetrachloroethylenea
1,1,2,2-Tetrachloroethanec
1,2-Dibromoethanec

0.47
1.1
0.025
0.2
0.35
0.017
0.095
0.024
0.019
0.023
0.074
0.12
0.11
0.014
0.21
0.034
0.046

0.46
2.7
0.025
0.24
0.17
0.017
0.047
0.0745
0.019
0.023
0.067
0.22
0.043
0.014
0.16
0.034
0.046

0.43
1.6
0.025
0.12
0.22
0.013
0.051
0.015
0.019
0.023
0.055
0.053
0.025
0.014
0.07
0.034
0.046

0.43
1.1
0.025
0.28
0.25
0.025
0.059
0.0225
0.019
0.023
0.082
0.085
0.032
0.014
0.2
0.034
0.046

0.39
1.4
0.025
0.31
0.37
0.025
0.082
0.027
0.019
0.023
0.075
0.18
0.063
0.014
0.28
0.034
0.046

0.43
1.2
0.025
0.25
0.24
0.11
0.059
0.0335
0.019
0.023
0.15
0.16
0.046
0.014
0.095
0.034
0.046

1.2
0.018
0.022
0.035
0.028
0.057
0.041
0.004
6.4
0.023
0.023

0.6
0.018
0.022
0.0235
0.028
0.053
0.05
0.004
8.1
0.023
0.023

0.55
0.018
0.022
0.0365
0.028
0.029
0.056
0.004
2.9
0.041
0.023

1.1
0.018
0.022
0.0345
0.028
0.062
0.057
0.004
6.1
0.065
0.023

0.56
0.018
0.022
0.037
0.028
0.044
0.14
0.004
5.5
0.052
0.023

1
0.018
0.022
0.0305
0.028
0.036
0.11
0.004
1.4
0.034
0.023

2.6
0.035
3.5
15
0.39
4
0.49

2.3
0.023
2.8
4.5
0.11
1.4
0.15

2.6
0.048
2.9
11
0.22
3.4
0.26

3.6
0.041
3.8
8.4
0.19
1.7
0.19

4.3
–
4.5
15
0.34
5.1
0.45

–
–
–
4.5
0.067
1.2
0.24

3-Chloro-1-propene
trans-1,3-Dichloropropenec
cis-1,3-Dichloropropenec
1,2-Dichloropropane
Hexachloro-1,3-butadienec
Chlorobenzene
o-Dichlorobenzene
m-Dichlorobenzenec
p-Dichlorobenzene
1,2,4-Trichlorobenzene
Benzyl chloridec
oxygenated compounds
Formaldehydea, dEthylene oxidee
Acetaldehydea, dAcetone1-Propanol
2-Propanol
Methyl ethyl ketone

Environ Sci Pollut Res (2012) 19:201–213

207

Table 3 (continued)

1-Butanola
Ethyl acetate
Methyl isobutyl ketone
Butyl acetate
Other organic compounds
Acrylonitrile

Sanda

Nishiwaki

Toyooka

SumotoAshiyaTakasago

3.8
3.2
0.5
1.2

0.94
0.7
0.25
0.55

3.6
0.97
0.28
0.56

3.4
0.69
0.29
0.84

6.1
4
0.63
0.89

0.46
0.91
0.35
0.37

0.15

0.077

0.091

0.14

0.15

0.14

a

This chemical showed statistically significant difference between the highest and the second highest median value in sampling sites (1%significance, Wilcoxon test)bThis chemical was detected in less than half of the samples, therefore a median value was reported as a half of the MDLcThis chemical was not detected, therefore mean and median values were reported as a half of the MDL

dAmbient air samples were collected at five sites but not at the industrial area (Takasago)eAmbient air samples were collected at four sites but not at the roadside area (Ashiya) or the industrial area (Takasago)

where RfC is the inhalation reference concentration(μg m−3). The inhalation reference concentration is an
estimate of a continuous inhalation exposure concentration
to people who are likely to be without risk of deleterious
effects for their lifetime. If the hazard quotient is morethan or equal to one, it is determined that a detailed
evaluation of the noncarcinogenic effect is required. The
reference concentration values for each substance weretaken first from the IRIS (US EPA 2010). When theenvironmental quality standard or guideline value of a
specific substance had been set in Japan, it was used as thereference concentration. However, because those of benzene, 1,3-butadiene, 1,2-dichloroethane, and vinyl chloride monomer are set on the basis of the carcinogenic
effect (Ministry of the Environment, Japan 2010a, b, c),reference concentrations for these substances were takenfrom the IRIS. The substances without any reference
concentrations were not included in the evaluation
process. Table 1 shows the reference concentration values
for measured substances.
2.3 Evaluation procedure on the photochemical reactivityof VOCs
The photochemical reactivity of these VOCs was evaluatedby calculating the ozone production (μg m−3).
Ozone production ¼ MIR  MC;
where maximum incremental reactivity (MIR) is the
maximum incremental reactivity. The maximum incremental reactivity is defined as the maximum amount ofozone that the component per unit weight can produce inthe atmosphere. The maximum incremental reactivity
provided by the CalEPA (2010) was used. The substances
without maximum incremental reactivity values were notincluded in the evaluation process. Table 2 shows the
maximum incremental reactivity of measured substances.
2.4 Statistical analysis
Mean, standard deviation, and median values were calculated for each chemicals, sampling sites, seasons, andmonths. It is not clear attempt analyzing these atmospheric
data using Student’s t test, as parametric data with limited
data number (n=15). Wilcoxon test were used median value
for nonparametric data in this study. Statistical confidence
level was given 1% to evaluate statistically significant
difference between the highest and the second highest
median value in sampling sites (1% significance, Wilcoxon
test).

3 Results and discussion
3.1 Concentrations of VOCs
The target compounds for measurement were 101 components of VOCs (31 alkanes, 12 alkenes, 18 aromatichydrocarbons, 28 organic halogen compounds, 11 oxygenated compounds, and one nitrogenous compound). Table 3
shows the concentrations of VOCs at sampling sites. The
data lower than the method detection limit (MDL) was
evaluated at half the concentration of the MDL value.
Methylcyclopentane and bromomethane were detected inless than half of the samples, therefore a median value wasreported as a half of the MDL. cis-1,2-Dichloroethylene,
1,1-dichloroethane, 1,1,2-trichloroethane, 1,1,2,2-tetrachloroethane, 1,2-dibromoethane, trans-1,3-dichloropropene, cis-1,3-dichloropropene, hexachloro-1,3-butadiene,m-dichlorobenzene, and benzyl chloride were not detected,

SandaNishiwaki

Acetaldehyde

1.0E-04

BenzeneEnviron Sci Pollut Res (2012) 19:201–213
Toyooka

SumotoAshiyaTakasago

1.0E-05
1.0E-06

monomer

Vinyl chloride

Dichloromethane

Carbontetrachloride

1,2Dichloroethane

1,3-Butadiene

Chloroform

1.0E-08

Acrylonitrile

1.0E-07

Formaldehyde

Excess cancer incidence

208

Fig. 2 Health risk estimation for VOCs by excess cancer incidence.
The target compounds of health risk estimation by excess cancer
incidence are ten VOCs which the unit risk values are established by
US EPA. The vertical axes are shown as logarithmic scales. For

formaldehyde, acrylonitrile, and acetaldehyde, the excess cancer
incidences were more than ten to five of the level of concern for
carcinogenic effect at one or more sites. Particularly, in formaldehyde,
they were in the ten to four to ten to five range at all sites

therefore mean and median values were reported as a halfof the MDL. The difference between the highest and thesecond highest median values in the sampling sites was
examined statistically using a Wilcoxon test, one of nonparametric statistical tests. As a result, the substances thatthe difference was significant at a 1% level were n-butane,
isobutane, cyclopentane, n-hexane, n-nonane, n-undecane,
n-dodecane, n-tridecane, n-tetradecane, n-hexadecane, 2methyl-1,3-butadiene, styrene, 1,2,4-trimethylbenzene,
dichloromethane, vinyl chloride monomer, 1,1-dichloro-

Sanda

Toyooka

SumotoAshiyaTakasago

1.0E-02
1.0E-03
1.0E-04

Methyl chloride

Bromomethane
1,1,1-

Trichloroethane

Takasago

Ethyl chloride

XyleneAshiyaMethyl ethyl ketone

ketoneSumotoMethyl isobutyl

Dichloroethylene

Toyooka

1,1-

Cyclohexane

n-HexaneDichloromethane

Chloroformp-

Nishiwaki

Isopropylbenzene

Trichloroethylene

Tetrachloroethylene

monomer

Vinyl chloride

Ethylbenzene

Fig. 3 Health risk estimation for VOCs by hazard quotient. The target
compounds of health risk estimation by hazard quotient are 26 VOCs
which the reference concentration values are established by US EPA,
etc. The vertical axes are shown as logarithmic scales. Although the

Dichlorobenzene

Formaldehyde

BenzeneTolueneAcetaldehyde

1,3-Butadiene

Sanda

Styrene

1.0E+00
1.0E-01
1.0E-02
1.0E-03
1.0E-04
1.0E-05
1.0E-06

Acrylonitrile

1.0E-05
1.0E-06

Hazard quotient

Nishiwaki

1.0E-01

Carbon tetrachloride

Hazard quotient

1.0E+00

hazard quotients of acrylonitrile, 1,3-butadiene, acetaldehyde, andtoluene were higher than those of other substances, they were less than
one of the level of concern for noncarcinogenic effect at all sites

Environ Sci Pollut Res (2012) 19:201–213

As a result of the above evaluation, toluene and formaldehyde were selected as the substances requiring emissions
600
Other 87 substances
1,2,4-Trimethylbenzene
Ethylbenzene
Acetaldehyde
Formaldehydem-,p-Xylene
1-Butene
Toluene

500

400

300

200

Takasago

AshiyaSumoto0

Toyooka100

Nishiwaki

The excess cancer incidences were calculated using VOCs
measured data and the unit risk values to evaluate humanhealth risk for carcinogenic effect. Table 1 shows the unit
risk values for the measured substances. The unit risk value
for benzene is set to be in the 2.2×10−6 per μg m−3 to 7.8×
10−6 per μg m−3 range. In this study, 5.0×10−6 per μg m−3
of a median was used to calculate the excess cancer
incidence. Figure 2 shows the health risk estimation for
VOCs by excess cancer incidence. For formaldehyde,
acrylonitrile, and acetaldehyde, the excess cancer incidences were more than 10−5 of the level of concern for
carcinogenic effect at one or more sites. Particularly, for

3.3 Concentration trend of the selected substancesSanda

3.2 Evaluation on the hazardousness and the photochemical
reactivity of VOCs

formaldehyde, they were in the 10−4 to 10−5 range at allsites. This result indicated the need to reduce formaldehyde
emissions from the standpoint of their carcinogenic risk.
The hazard quotients were calculated using VOCs measured data and the reference concentration to evaluate
human health risk for noncarcinogenic effect. The reference
concentration values for the measured substances are shownin Table 1. Figure 3 shows the health risk estimation for
VOCs by the hazard quotient. Although the hazard quotientsof acrylonitrile, 1,3-butadiene, acetaldehyde, and toluene
were higher than those of other substances, they were lessthan 1 of the level of concern for noncarcinogenic effect at
all sites. This suggested that the need for reduction measuresof the noncarcinogenic effect is small at this time. The ozone
productions were calculated using VOCs measured data andthe MIR values to evaluate the photochemical reactivity. The
MIR values for the measured substances are shown in
Table 2. Figure 4 shows the calculation results of the ozone
productions for VOCs. Toluene had a high percentage of theozone production at all sites. This result indicated the need toreduce toluene emissions from the standpoint of thephotochemical oxidant formation.

Ozone production (µg/m3)

ethylene, 1,2-dichloroethane, 1,1,1-trichloroethane, tetrachloroethylene, formaldehyde, acetaldehyde, and 1butanol. In industrial area (Takasago), n-hexadecane,styrene, vinyl chloride monomer, and 1,2-dichloroethane
showed a high concentration. In roadside area (Ashiya), nhexane, n-undecane, n-dodecane, tetrachloroethylene, formaldehyde, acetaldehyde, and 1-butanol showed a highconcentration. Takasago is typically an industrial area
where many manufacturing factories are located aroundthe sampling site. One of them is a polyvinylchloride
factory. Vinyl chloride monomer is used in the productionof polyvinylchloride (Na et al. 2001). 1,2-Dichloroethane isintermediate for synthesis of vinyl chloride monomer(Incavo 1996; Sotowa et al. 1999). These results suggested
that the exhaust gas from this factory influenced the highconcentration of these chemicals only in Takasago. nHexane and n-undecane are components of gasoline and nundecane, n-dodecane, and n-hexadecane are ones of light
diesel oil. Additionally, styrene, formaldehyde, and acetaldehyde are the substances that the emission from automobile is large in Japan (Ministry of the Environment, Japan2010a, b, c). These results suggested that the emission fromautomobile influenced the high concentration of n-hexadecane and styrene only in Takasago and n-hexane, nundecane, n-dodecane, formaldehyde, and acetaldehyde
only in Ashiya. The reason for the higher concentrationsof tetrachloroethylene and 1-butanol only in Ashiya needs
more investigation. In other substances, n-butane showed ahigh concentration only in Sumoto urban area. The
sampling site in Sumoto is located in the center of the city,and there is a lot of traffic around the site. Olson et al.
(2009) have reported that concentrations of 55 VOCs were
measured near the roadway and n-butane was one of thehighest concentration chemicals of individual VOCs. These
results suggested that the emission from automobile
influenced the high concentration of this chemical only in
Sumoto.

209

Sampling site
Fig. 4 Ozone production for VOCs at sampling sites. The individualozone productions of 87 VOCs except toluene, 1-butene, m-,p-xylene,
formaldehyde, acetaldehyde, ethylbenzene, and 1,2,4-trimethylbenzene were, respectively, low. Thus, for 87 VOCs, the total amount ofeach ozone production was indicated. At all sites, toluene had a highpercentage of the ozone production

210

Environ Sci Pollut Res (2012) 19:201–213
40

Sanda
Nishiwaki
Toyooka
SumotoAshiyaTakasago30
25

traffic around the sampling site because of rapid urbanization over the last few years, that the high concentration in2007 in Takasago is due to the influence of industrial fume
because of the presence of factories that emitted toluene
around the sampling site, and that many of the predominantwind directions at the time of measurement were on theside of the factories in 2007. Toluene concentration inroadside area (Ashiya) was not high compared with theother areas. This result was in contrast with the previous
study that the highest concentration of toluene wasobserved at the site exposed directly to road traffic
emissions (Kerbachi et al. 2006). The trends of the seasonal
concentrations for toluene at sampling sites are shown in
Fig. 6. The seasonal concentration trend differed according
to the sampling site. The differences in toluene concentrations between summer and winter are uncertain at allsites, although Parra et al. (2009) have reported that toluene
concentration was higher in winter than in summer due tohigher atmospheric stability. Toluene is emitted from manysources such as vehicle exhaust, solvent use, gasoline
evaporation, fossil fuel combustion, landfill, tobaccosmoke, or adhesive (Baek and Jenkins 2004; Filella andPenuelas 2006; Kim and Kim 2002; Na et al. 2004; Sack et
al. 1992). Therefore, it was presumed that the interannual
and seasonal trends of toluene concentrations were different
at a regional level because the conditions of the above
emission sources, wind direction, and wind speed had asignificant influence on the toluene concentration.

20
15
10
5
2009

Fig. 5 The trends of the annual mean concentrations for toluene at
sampling sites. The interannual change tendencies of toluene concentrations were different at a regional level. It was determined that theannual mean concentrations generally continued to be flat in
Nishiwaki, Toyooka, Sumoto, and Ashiya and exhibited an increasing
tendency in Sanda. And, in Takasago, the annual mean concentrationin 2007 was relatively higher than others

reduction. The state and characteristics of environmental
pollution were considered from the concentration trends ofthese substances.
3.3.1 Toluene
The trends of the annual mean concentrations for toluene at
sampling sites are shown in Fig. 5. The interannual change
tendencies of toluene concentrations were different at aregional level. It was determined that the annual mean
concentrations generally continued to be flat in Nishiwaki,
Toyooka, Sumoto, and Ashiya, and exhibited an increasing
tendency in Sanda. In Takasago, the annual mean concentration in 2007 was relatively higher than the others. It
could be that the concentration tendency in Sanda is due tothe influence of vehicle emission owing to the increase in

The trends of the annual mean concentrations for formaldehyde at the sampling sites are shown in Fig. 7.
Formaldehyde concentrations have been reduced at all sites
in 2009 compared in the previous year. Especially, inAshiya, it exhibited relatively more reduction rate thanothers. This could be because of the decrease in traffic. The
comprehension of the future concentration trend is required

25
Sanda

Nishiwaki

ToyookaAshiyaSumotoTakasago

20
15
10

winterautumnspringsummerwinterautumnspringsummerwinterautumnsummerwinterspringautumnwinter0

autumn5springsummerConcentration (µg/m3)

Fig. 6 The trends of the seasonal concentrations for toluene
at sampling sites (median)

3.3.2 Formaldehyde

spring2008

summer

2007

Year

winter2006

autumn2005

spring0summerConcentration (µg/m3)

35

Environ Sci Pollut Res (2012) 19:201–213

211

6

Sanda
Nishiwaki
Toyooka
SumotoAshiya

4
3
2
1

2009

Fig. 7 The trends of the annual mean concentrations for formaldehyde at sampling sites. Formaldehyde concentrations have been
reduced at all sites in 2009 compared in the previous year. Especially,in Ashiya, it exhibited relatively more reduction rate than others

to identify the exact reason. The trends of the seasonal
concentrations for formaldehyde at sampling sites areshown in Fig. 8. The seasonal concentrations increased
from spring to summer and decreased from summer towinter at all the urban sites. The seasonal concentrations
increased from spring to summer and decreased fromsummer to winter at all the urban sites. There weresignificant differences between formaldehyde concentrations in summer and winter at above sites except Ashiya as
roadside area (1% significance, Wilcoxon test). The exact
reason for this needs more investigation. The above
seasonal patterns of formaldehyde in urban areas wereconsistent with those from other studies (Ceron et al. 2007;
Ho et al. 2002; Pang and Mu 2006). For example, Ceron etal. measured the concentrations of 5 carbonyl compounds
including formaldehyde in a semi-urban site and found thatthe levels of carbonyl compounds showed a strong seasonal
trend with the following relative abundance: summer >6

The atmospheric concentrations of 101 components of
VOCs were measured at six sites which comprehend foururban areas, a roadside area, and an industrial area in
Hyogo Prefecture. VOCs influence on hazardousness andphotochemical reactivity were evaluated using VOCs
measured data and the index on the health effect evaluationand ozone formation potential. As a result, excess cancer
incidences for formaldehyde exceeded 10−5 of the level ofconcern for carcinogenic effect at all sites. In addition,
toluene had a high percentage of ozone productions. The
state and characteristics of environmental pollution wereconsidered from the concentration trends of toluene andformaldehyde. Therefore, it was presumed that the interannual and seasonal trends of toluene concentrations weredifferent at a regional level because the conditions of above
emission sources, wind direction, and wind speed had asignificant influence on the toluene concentration. It wasquite possible that formaldehyde concentrations in summer
were significantly higher than those in winter at the urbansites because the formation of photochemical oxidant had a

Sadna

SumotoTakooyoNishiwaki

Ashiya5
4
3
2

winterautumnsummerspringwinterautumnspringsummerwinterautumnsummerautumn0summer1

springConcentration (µg/m3)

Fig. 8 The trends of the seasonal
concentrations for formaldehyde
at sampling sites (median). The
seasonal concentrations increased
from spring to summer and decreased from summer to winter at
all the urban sites. There weresignificant differences between
formaldehyde concentrations insummer and winter at above sites
except Ashioya as roadside area
(1% significance, Wilcoxon test)

4 Conclusions

spring2008

winter2007

Year

autumn2006

spring2005

summer0

winterConcentration (µg/m3)

5

autumn > winter because photochemical activity andtemperature played an important role in the creation ofcarbonyl compounds in the sampling site during thesummer. Ho et al. determined ambient levels of fivecarbonyl compounds including formaldehyde in urban areaand found that the mean concentrations of formaldehyde
and acetaldehyde were significantly higher in summer
because they were produced photochemically at a higher
level in summer. Therefore, it was quite possible that theformaldehyde concentrations in summer were significantly
higher than those in winter at the urban sites because theformation of photochemical oxidant had a significant
impact on the formaldehyde concentration in summer.

212

significant impact on the formaldehyde concentration insummer. The results show the need to prepare the emission
reduction plan for the major sources such as vehicle
exhaust, solvent use, and industrial processes to diminish
the concentration of toluene that contributes significantly tothe formation of photochemical oxidant.

Open Access This article is distributed under the terms of theCreative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any
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