Decline of VOC Concentrations with the Aging of Houses in Japan

doi:10.4236/jep.2013.412A1004

Paper Menu >>

Journal Menu >>

Journal of Environmental Protection, 2013, 4, 33-40

Published Online December 2013 (http://www.scirp.org/journal/jep)

http://dx.doi.org/10.4236/jep.2013.412A1004

Open Access JEP

Decline of VOC Concentrations with the Aging of Houses

in Japan

Motoya Hayashi1, Haruki Osawa2

1Department of Life Style and Space Design, Miyagi Gakuin Women’s University, Sendai, Japan; 2Department of Healthy Building

and Housing, National Institute of Public Health, Wako, Japan.

Email: [email protected].jp, [email protected]

Received September 8th, 2013; revised October 12th, 2013; accepted November 7th, 2013

tion License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly

ABSTRACT

The purpose of this investig ation is to know the long-term characteristics of VOC concentrations in houses bu ilt before

the building code in 2003 and to clarify th e coun termeasures against indoor air po llution in the houses already built. For

example, the improvements of living habits, ventilation and the remove of building materials. The concentrations of

VOCs were measured in these houses in summer and winter from 2000 to 2005. The results showed that the concentra-

tion of formaldehyde decreased in the first year. After that the decline of the concentration was not seen and the con-

centration chang ed only with the temperature. The characteristics of decline were thought to be caused by two sorts of

emission. One is an emission of concealed formaldehyde in the process of material production and the other is an emis-

sion with the generation of formaldehyde from adhesives of urea resin and moisture. The concentration of toluene de-

creased rapidly in the first year. The concentrations of xylene, ethyl-benzene and styrene showed a similar change. But

the concentrations of acetaldehyde which were measured from the summer of 2002 did not decrease and its concentra-

tion in some houses was higher than the guideline even in the winter of 2005.

Keywords: Indoor Air Quality; VOC; Passive Sampling; Questionnaire Survey; Statistics Analysis

1. Introduction

A traditional Japanese house has a structure of wooden

posts and beams. Houses with this structure have wide

openings. Therefore the traditional house is beneficial to

indoor cooling in summer and to the prevention of the

deterioration of wooden materials. Also there are many

air infiltration routes through the wall, floor, ceiling, etc.

Since 1970s, the structures have been improved to be

airtight and insulated using insulation materials and films.

However, many infiltration routes lurk in the concealed

spaces like spaces inside the walls, the ceilings and the

floors [1].

The living style of Japanese dwellers has changed in

the sixty years after World War 2. The unoccupied time

in houses became longer, because the number of family

became smaller. And the time of opening windows be-

came shorter with the spread of air conditioner. New

building materials have been produced in factories since

1960s, and prefabricated houses have expanded in Japan

since 1970s. Under these situations, “sick house”: the

indoor air pollution by chemical compounds from build-

ing materials, has been closed up in Japan since 1990s.

And many countermeasures against indoor air pollution

in houses have been taken by the Japanese government,

building companies, building material manufacturers and

other related groups. And a new building code with

countermeasures against indoor air pollution has been

forced by the Ministry of Land, Infrastructure and

Transport since 2003. According to this building code the

concentration of formaldehyde is expected to be lower

than the guideline: 0.08 ppm, which was established by

the Ministry of Health, Labour and Welfare of Japanese

Government in 1993. This building code requires our

consideration about the emission rate of formaldehyde

from building materials. The regulated materials are not

only building materials which are used for interior finish

but also materials which are concealed in walls, ceilings

and floors. And the installation of ventilation equipment

Decline of VOC Concentrations with the Aging of Houses in Japan

is required in all residential spaces. The required ventila-

tion time is 0.5 times per hour [2]. Before this building

code, the concentrations of formaldehyde were higher

than the guideline at the completion of houses in many

cases. And some investigations showed that the concen-

trations of formaldehyde do not decrease with time soon

[3-8]. Organic compounds are volatizing from building

materials and from furniture and articles which are car-

ried into houses by residents, so the indoor concentra-

tions do not decrease with the aging of houses. Therefore

the influences of indoor pollution on the residents’ health

may continue long and these influences may become a

cause of a multiple chemical sensitivity [1]. Under these

contexts the decline of concentrations with the aging of

houses was investigated.

2. Methods

The concentrations of formaldehyde, toluene, xylene,

ethyl-benzene, styrene and acetaldehyde were measured

in winter and in summer for five years in about two hun-

dred and fifty houses in which formaldehyde concentra-

tion was higher than the guideline: 0.08ppm in 2000. The

first investigations in 2000 were carried out from sum-

mer to winter continuously in new houses which were

built less than a year ago. The number of investigated

houses decreased gradually and became eighty-four in

the winter of 2005 as shown in Figure 1. The concentra-

tions were measured using passive samplers made by

Advanced Chemical Sensor Inc. The samplers were sent

to the residents from a laboratory. The residents placed

samplers in the rooms for 24 hours and sent them back to

the laboratory. The concentrations were specified using

gas chromatographs in the laboratory. The characteristics

of buildings and residents were checked using question-

naires. The indoor temperatures and the humidity were

measured by residents and were checked on the ques-

tionnaires. The number of investigated houses changed.

But the results of statistical analysis using the eig hty-four

houses in which the concentrations were obtained during

all the periods were quite similar to the results using all

the data. The difference between the average formalde-

hyde concentration of these eighty-four houses and that

of all the houses is smaller than 4%. Th erefore the resu lts

using all the data are reported in this paper.

3. Results

Figure 2 shows classifications of investigated houses.

They consist of apartment houses and detached houses.

Most apartment houses were built with reinforced con-

crete structure. And the numbers of stories of 45% of the

apartment houses were from one to three. And those of

the other apartment houses were from three to ten. The

100

200

300

20002001sum 2001win 2002sum 2002win 2003sum 2003win 2004sum 2004win 2005sum 2005win

Number of houses

Detached houseApartment house

Figure 1. Number of investigated houses.

20%

40%

60%

80%

100%

2000-2005

partment house

Detached house

20%

40%

60%

80%

100%

2000-2005

2inch X4inch wooden stud

structu re

Wooden post and beam

structu re

Prefabricated wooden panel

structu re

Prefabricated steal structure

Reinforced concrete structure

The other

Figure 2. Classification of houses.

Open Access JEP

Decline of VOC Concentrations with the Aging of Houses in Japan 35

structure types of detached houses were various but most

detached houses were built with wooden post and beam

structure which is common in Japan. Another structure

was 2 inch × 4 inch wooden stud structure which has

been imported and built generally since 1980s. The oth-

ers were prefabricated structures. Most of the prefabri-

cated houses are produced in large factories by major

housing companies. The percentage of the classification

of houses was similar to the percentage of all houses

built recently in Jap an.

Figure 3 shows the weather conditions an d the humid-

ity when the concentrations were measured in houses. In

summer, the percentage of “cloudy” was a little smaller

than that in winter. The temperatures were shown in Fig-

ure 4. Naturally the temperatures were high in summer

and low in winter. The humidity changed with the tem-

perature; it is hot and humid in summer and it is cold in

winter. This annual change is typic al in m ost a reas of Japa n.

Figure 5 shows how long the residents keep the win-

dows of their houses open in a day. The percentage of

open windows does not contain the percentage in the

case that the windows are open for less than one hour.

Naturally the percentage of open windows is larger in

summer than in winter.

20%

40%

60%

80%

100%

Sum Win

Cloudy Rain Sunny

20%

40%

60%

80%

100%

Sum Win

20-39 40-5960-

Figure 3. Weather and humidity.

20.9

29.1

21.4

27.4

21.1

27.6

19.2

28.8

17.4

27.1

15.7

0.11

0.07

0.03

0.05

0.03

0.06

0.03

0.06

0.02

0.05

0.02

0.151

0.022

0.0130.010

0.006 0.009

0.0040.0040.003 0.001 0.002

20002001sum2001win 2002sum2002win 2003sum2003win 2004sum2004win 2005sum2005win

Temperature (deg.C)

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Concentration (ppm)

Indoor temerature (degC)FormaldehydeToluene

Figure 4. Change of temperature and concentrations.

Open Access JEP

Decline of VOC Concentrations with the Aging of Houses in Japan

Figure 6 shows the changes of formaldehyde concen-

trations. In this figure the standard deviations of concen-

trations on each measurement period are showed using

lines. The average of concentration of formaldehyde was

higher than the guideline: 0.08ppm in 2000. This is be-

cause the houses were chosen from the houses in which

the concentration exceeded the guideline when investi-

gated in 2000. The concentration of formaldehyde de-

creased from 2000 to the winter of 2001 but the concen-

tration increased in the summer of 2002. After 2003, the

concentration increased in summer and decreased in

winter. This annual change was repeated during the four

years.

Figure 7 shows the concentration of toluene. The av-

erage concentration was higher than the guideline: 0.07

ppm in 2000. The concentrations decreased and became

lower than the guideline in the summer of 2001. The

concentrations did not change with temperature. Figure

8 shows the concentration of xylene. The concentration

was lower than the guideline: 0.20 ppm in 2000. The

concentration decreased during the first year and was low

during these five years. In 2003 the concentration in-

creased a little but the reason was not clear.

20%

40%

60%

80%

100%

Sum Win

Opening windowsClosing windows

Figure 5. About opening windows.

Concentration of formaldehyde　(ppm)

0.113

0.073

0.031

0.054

0.033

0.059

0.025

0.060

0.021

0.046

0.019

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

20002001sum2001win 2002sum2002win 2003sum2003win 2004sum2004win 2005sum 2005win

Guidline:0.08ppm

Figure 6. Decline of formaldehyde concentration.

Concentration of toluene(ppm)

0.151

0.022 0.013 0.010 0.006 0.009 0.004 0.0040.0030.001 0.002

0.05

0.1

0.15

0.2

0.25

0.3

20002001sum 2001win2002sum2002win2003sum 2003win 2004sum 2004win2005sum 2005win

Guidline:0.07ppm

Figure 7. Decline of toluene concentration.

Open Access JEP

Decline of VOC Concentrations with the Aging of Houses in Japan 37

Concentration of xylene(ppm)

0.025

0.009 0.005 0.0030.002

0.009 0.010

0.000 0.003 0.000 0.002

0.02

0.04

0.06

0.08

0.1

0.12

2000 2001su

2001win 2002sum2002win 2003sum2003win 2004su

2004win2005sum 2005win

Guidline:0.20ppm

Figure 8. Decline of xylene concentration.

Figure 9 shows the concentration of ethyl-benzene.

The concentration was also very much lower than the

guideline: 0.88 ppm even in 2000. The concentration

decreased during the first year and was low after that. In

the winter of 2003 the concentratio n increased a little bu t

the reason was not clear. These temporary rises are

thought to be caused by the pollution sources like furni-

ture or insecticide which are carried in houses by resi-

dents.

Figure 10 shows the concentrations of styrene. The

average concen tration was lower than the guideline: 0.05

ppm in 2000. But in some houses the concentrations

were higher than the guideline. The concentration de-

creased during the first year and was lower during these

five years. In 2003 the concentration increased a little.

Figure 11 shows the concentration of acetaldehyde.

The concentration was measured after the summer of

2002. The concentration was not enough lower than the

guideline: 0.03 ppm in the summer of 2003. And the

concentration increased gradually during the four years.

The reason of this increase is not clear. One of the emis-

sion sources is smoking but the percentage of “smoking”

was almost 11% in all measurement periods. The other

source is thought to be building materials. Anyway it

became clear that the concentration of acetaldehyde ex-

ceeded the guideline in some houses.

Figure 12 shows the percentage of houses where the

residents felt physical changes in houses. The residents

answered the following question: Have you felt a change

of physical condition which is thought to be caused by

the chemical compound. If the answer was “yes”, the

following items were also checked: who felt the change,

the physical conditions, when the change was felt. And

the following physical conditions: nausea, headache,

eczema, the pain of eyes, nose and throat were appealed

on the questionnaires. The percentage of the residents

who felt the change of their physical conditions was lar-

ger in summer and smaller in winter. This change was

similar to that of the formaldehyde concentration shown

in Figure 4. But the percentage decreased gradually and

the fluctuation of the percentage also decreased. These

results show that it is necessary to investigate the rela-

tionship between the indoor air qu ality and the residents’

feeling about the change of physical condition which are

checked on the questionnaires. This investigation is ex-

pected to be made with their medical researchers.

Figure 4 shows the change of temperature and con-

centrations. The concentrations of formaldehyde changed

with temperature.

Figure 13 shows the relationship between tempera-

tures and concentrations. In the case of formaldehyde the

concentrations are distributed on a curve: “Calculation

(C25 = 0.046, a = 1.11)” in Figure 13. This curve is cal-

culated using the following equation.

T25

CCa



 (1)

where C: concentration,



C25E25 Q



, E25: emis-

sion rate when temperature is 25deg.C, Q: ventilation

rate, β: ratio of sink, a: coefficient of influence of tem-

perature (a = 1.11: a value which was measured in small

chambers).

The formaldehyde concentration in 2000 was not on

the curve but the other co ncentrations fitted o n this curve

generally. This shows that the ability of formaldehyde

emission hardly decreased after 2001.

Figure 14 shows the measured concentrations of for-

maldehyde and the normalized concentrations: C25

which is calculated using equation 1. The normalized

concentration is thought to be an indicator of emission

possibility in a house. The normalized concentration de-

creased fast from 2000 to the summer of 2001 and was

steady after that. This charcteristic of concentration a

Open Access JEP

Decline of VOC Concentrations with the Aging of Houses in Japan

Concentration of ethyl-benzene （ppm）

0.025

0.003 0.000 0.000 0.001 0.001 0.004

0.000 0.000 0.000 0.000

0.01

0.02

0.03

0.04

0.05

0.06

20002001sum 2001win2002sum 2002win2003sum 2003win2004sum 2004win2005sum 2005win

Guidline:0.88ppm

Figure 9. Decline of ethyl-benzene concentration.

Concentration of styrene （ppm）

0.025

0.009 0.005 0.003 0.002

0.009 0.010

0.000 0.003 0.000 0.002

0.02

0.04

0.06

0.08

0.1

0.12

20002001sum 2001win2002sum 2002win2003sum 2003win2004sum 2004win2005sum 2005win

Guidline:0.05ppm

Figure 10. Decline of styrene concentration.

Concentration of acetaldehyde(ppm)

0.012

0.016 0.015 0.013

0.019

0.017

0.015

0.018

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

20002001sum 2001win2002sum 2002win2003sum 2003win2004sum2004win2005sum 2005win

Guidline:0.03ppm

Figure 11. Decline of acetaldehyde concentration.

Open Access JEP

Decline of VOC Concentrations with the Aging of Houses in Japan 39

Percentage of houses where residents felt the change of physical condition(%)

2.7%

18.4%

4.3%

13.8%

3.0%

5.6% 4.2%

10%

15%

20%

25%

20002001sum2001win2002sum 2002win2003sum 2003win

Figure 12. Percentages about change of physical condition with chemical co mpound.

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

10 15 2025 30 35

Indoor temperature (degC)

Concentration (ppm)

Formaldehyde

Equation 1 (C25=0.046, a=1.11)

Toluene

2000

2001 sum.

Figure 13. Relationship between temperatures and concentrations.

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

2000/

2001/

2002/

2003/

2004/

2005/

Concentration (ppm)

F ormaldehy de

F ormaldehy de(T=25degC)

Figure 14. Change of the normalized formaldehyde concentration at a temperature 25˚C.

Open Access JEP

Decline of VOC Concentrations with the Aging of Houses in Japan

Open Access JEP

decline may be caused by a mechanism of emission from

building materials. In Japanese houses main emission

sources of formaldehyde were wooden building materials

produced in factories like plywood and particle board. In

the case of houses built in 2000, most of these materials

were made using adhesives of urea resin which is made

with formaldehyde. A part of formaldehyde was con-

cealed in the materials when they were produced in fac-

tories. Soon after production these concealed formalde-

hyde may start to volatilize. On the other hand formal-

dehyde is generated from inside urea resin and moisture

after production. The generation rate is influenced by

temperature and humidity. And the generated formalde-

hyde diffuses to the surface and volatilizes into indoor air.

The calculated decline curve of normalized concentration

shows that the emission of concealed formaldehyde fin-

ished in almost one year and the emission with the gen-

eration of formaldeh yde contin ues for a long ti me at least

for five years. The emission will continue until all the

sources of formaldehyde are lost.

4. Conclusion

The investigation on the decline of indoor chemical pol-

lution was carried out in Japanese houses. The concen-

trations of toluene, xylene, ethyl-benzene, styrene de-

crease fast and the concentrations were lower than the

guidelines in most houses at least after one year. But the

concentrations of formaldehyde and acetaldehyde were

above the safety zone. In the case of formaldehyde the

concentration decreased during the first one year but the

concentration did not decrease at all during the next four

years. The concentration became higher in summer every

year. Therefore the long-term countermeasure against

chemical pollution in su mmer is thought to be necessary.

If residents have suffered some impairment by indoor

chemical pollution, renovations of buildings especially

considering indoor air quality will be necessary not only

in new houses but als o in ol d ho uses.

5. Acknowledgements

The study was a part of a national project “Development

of Countermeasure Technology on Residential Indoor

Air Quality” by National Institute for Land and Infra-

structure Management under the Japanese government.

The investigations were made with the contributions of

many residents. And the investigations were made with

the cooperation of Center for Housing Renovation and

Dispute Settlement Support and the students of Miyagi-

gakuin Women’s University. The authors express their

gratitude to them and to Dr. Kouichi Ikeda of National

Institute of Public Health, Dr. Yasuo Kuwasawa of Na-

tional Institute for Land and Infrastructure Management,

Prof. Hiroshi Yoshino of Tohoku University and the

committees of the nationa l pro jects.

REFERENCES

[1] H. Motoya and O. Haruki, “The Influence of the Con-

cealed Pollution Sources upon the Indoor Air Quality in

Houses,” Building and Environment, Vol. 43, 2008, pp.

329-336.

http://dx.doi.org/10.1016/j.buildenv.2006.03.022

[2] H. Motoya, E. Masamichi and H. Yoshiko, “Annual Cha-

racteristics of Ventilation and Indoor Air Quality in De-

tached Houses Using a Simulation Method with Japanese

Daily Schedule Model,” Building and Environment, Vol.

36, No. 6, 2001, pp. 721-731.

[3] H. Osawa and M. Hayashi, “Status of the Indoor Air

Chemical Pollution in Japanese Houses Based on the Na-

tionwide Field Survey from 2000 to 2005,” The Interna-

tional Journal of Building Science and Its Applications

Building and Environment, Vol. 44, 2009, pp. 1330-1336.

http://dx.doi.org/10.1016/j.buildenv.2008.06.022

[4] K. Kumagai, K. Ikeda, M. Hori, T. Matsumura, A. No-

zaki, H. Kimura, et al., “Field Study on Volatile Organic

Compounds in Residences,” Journal of Architecture,

Planning and Environmental Engineering: Transactions

of AIJ, No. 522, 1999, pp. 45-52.

[5] Y. Hiroshi, A. Kentaro, M. Mari, N. Koji, I. Koichi, N.

Atsuo, et al., “Long-Termed Field Survey of Indoor Air

Quality and Health Hazards in Sick House,” Journal of

Asian Architecture and Building Engineering, Vol. 3, No.

2, 2004, pp. 297-303.

http://dx.doi.org/10.3130/jaabe.3.297

[6] Y. P. Zhang, X. X. Luo, X. K. Wang, K. Qian and R. Y.

Zhao, “Influence of Temperature on Formaldehyde Emis-

sion Parameters of Dry Building Materials,” Atmospheric

Environment, Vol. 41, No. 15, 2007, pp. 3203-3216.

http://dx.doi.org/10.1016/j.atmosenv.2006.10.081

[7] B. Son, P. Breysse and W. Yang, “Volatile Organic Com-

pound Concentrations in Residential Indoor and Outdoor

and Its Personal Exposure in Korea,” Environment Inter-

national, Vol. 29, No. 1, 2003, pp. 79-85.

http://dx.doi.org/10.1016/S0160-4120(02)00148-4

[8] I. Aydin, G. Colakoglu, S. Colak and C. Demirkir, “Ef-

fects of Moisture Content on Formaldehyde Emission and

Mechanical Properties of Plywood,” Building and Envi-

ronment, Vol. 41, No. 10, 2006, pp. 1311-1316.

http://dx.doi.org/10.1016/j.buildenv.2005.05.011