ASSESSMENT ON PHYSICAL FACTORS OF THERMAL COMFORT, …

International Journal of Public Health and Clinical Sciences e-ISSN : 2289-7577. Vol. 2:No. 3

May/June 2015

Nurul Atikah Rohizan, Abidin E.Z. 59

IJPHCS

Open Access: e-Journal

ASSESSMENT ON PHYSICAL FACTORS OF THERMAL

COMFORT, SICK BUILDING SYNDROME SYMPTOMS AND

PERCEPTION OF COMFORT AMONG OCCUPANTS IN A

PUBLIC RESEARCH UNIVERSITY LABORATORY

BUILDING

Nurul Atikah Rohizan1, Abidin E.Z.

1*

1Department of Environmental and Occupational Health, Faculty of Medicine and Health

Sciences, Universiti Putra Malaysia

*Corresponding author: Emilia Zainal Abidin, Department of Environmental and

Occupational Health, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia,

UPM Serdang, 43400 Selangor, Malaysia; Email: [email protected]

ABSTRACT

Background: Sick Building Syndrome (SBS) is a phenomenon where people have a range of

symptoms related to a certain building conditions, most often a workplace. Physical

environmental factors is one of the contributors of SBS. This study aimed to determine the

association between SBS symptoms and perception of comfort with physical factors among

occupants in offices at a public university in Malaysia.

Materials and Methods: This was a cross-sectional study conducted among 175 occupants in

19 offices inside a laboratory complex of a university performed in 2015. SBS symptoms and

perception of comfort were assessed using a self-administered questionnaire. Measurements

of physical factors for temperature, relative humidity (RH) and air velocity were performed.

Data was analysed using a statistical software.

Result: About 90% of respondents were female and were of Malay ethnicity. The prevalence

of SBS is 9.7% while 11% of the respondents reported the perception of discomfort. The

average temperature was 25.1±0.5 ºC, while for RH the average was 69.0±1.2%. The average

air velocity was 0.2±0.03 m/s. All the averages were within the occupational limit set in

Malaysia. From the multivariate analysis, it was found that higher level of RH (Odds Ratio,

OR=4.05, 95%Confidence Interval, CI=1.27-12.9) and the female gender (OR=5.12, 95%

CI=1.5-17.3) contributed significantly to the reporting of SBS while for perception of

comfort, lower temperature (OR=10.76, 95% CI=2.17-53.5), higher level of RH (OR=15.2,

95% CI=4.28-54.1) and the female gender (OR=6.52, 95% CI=1.49-28.6) were significant

contributors.

Conclusion: This study found significant relationship between RH with SBS and perception

of comfort. There is a need to ensure proper ventilation system and its continuous

maintenance are provided by employers to ensure workers continue to be safe and healthy.

Keywords: Sick building syndrome, thermal comfort, perception, indoor air quality, offices


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1.0 Introduction

Sick building syndrome or SBS is a poorly understood phenomenon where people have a

range of symptoms related to a certain building conditions, most often a workplace, and there

is no specific identifiable cause (Wang et al., 2008). SBS symptoms may include headache,

lethargy, eye, nose and throat irritation, breathing problems and skin irritation (Sarafis et al.,

2010). Thermal comfort has been described as a state of mind on the satisfaction of indoor

thermal environment (ASHRAE, 2010). It is influenced by physical variables that affect the

heat and mass transfer in energy balance model and is often characterized using thermal

comfort scale in which its average is called predicted mean vote. Results from the evaluation

and analysis of 95 buildings have showed significant effects of temperature on the prevalence

of SBS despite the physical factors being within the comfort zone (Mendell and Mirer, 2009).

Comfort zone is defined as a range of thermal environmental conditions of which more than

80% of occupants express satisfaction (ASHRAE, 2004). Increased severity of SBS

symptoms may negatively impact the performance of work of the affected occupants

(Seppänen and Fisk, 2006).

Internationally, several standards for indoor air quality (IAQ) have been identified. The

allowable range of temperature set by the American Society of Heating, Refrigerating, and

Air-Conditioning Engineers (ASHRAE) is between 21-23°C, while for RH, the allowable

range is between 20-70% and lastly for air velocity, the permissible value established is ≤

0.25 m/s (ASHRAE, 2013). In Malaysia, indoor air quality has been given due consideration

as one of the factors contributing to the safety and health of workers. The Department of

Occupational Safety and Health (DOSH) have introduced an Industrial Code of Practice

(ICOP) for Indoor Air Quality (IAQ) in 2010 (DOSH. 2010). The allowable range of

temperature set by ICOP, DOSH is between 23-26ºC, for RH, the allowable range is between

40-70% and lastly for air velocity, the permissible value established is between 0.15-0.50 m/s.

A study in the United Kingdom among office workers found that SBS was associated with

poor supervisor support and perception of poor physical environmental conditions at work

(Marmot et al, 2006). Possible risk factors for SBS may include poor ventilation (Seppänen et

al., 2003), low humidity (Mi et al., 2006) and high temperature or changes in temperature

throughout the day (Jones, 1999). A local study in Malaysia has been performed by

comparing the physical parameters of an old and a new building (Fadilah and Juliana, 2012).

The new building which has a lower temperature comply with the guidelines published by

ICOP, DOSH and had lower prevalence of SBS among its workers compared to the old

building which had a higher temperature range and slightly exceed the requirement by ICOP,

DOSH. The SBS prevalence among its workers was higher. Another study by Zamani et al.

(2013) concluded that an increase in ventilation rate would significantly reduce the prevalence

of SBS.

The use of Mechanical Ventilation And Air-Conditioning (MVAC) system is very common in

offices in Malaysia. Due to the tropical climate, air-conditioning is essential to ensure that the

temperature continue to stabilize within the range considered as acceptable. A well-

functioning mechanical ventilation system is a must in order to maintain a good indoor air

quality (Jones, 1999). The problem with the use of MVAC system is the issue of energy

saving, where the exchange of indoor and outdoor air or ventilation are reduced to the

minimal. Indoor humidity is influenced by ventilation rates with lower ventilation increases


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indoor moisture levels (Institute of Medicine, 2004) which in turn increases the RH. As have

been reiterated earlier, higher RH has been associated with SBS, which may also be linked to

the presence of mould as mould growth is supported in environment with low temperature and

high RH (Engvall et al., 2001). As such, problem with the IAQ is common in indoor offices

serviced by MVAC system.

Unofficial complaints regarding IAQ problem among office workers prompted a further

investigation in a set of offices housed in a laboratory complex of a public research university

in Selangor. It was reported that modifications to the offices have been made to add more

space for lecturers, support staffs and research assistants in 2013. Since then, many official

complaints were received from the building occupants about their discomfort that is believed

to have been due to improper ventilation system. Most of the complaints received were about

their dissatisfaction over thermal comfort and the occurrence of visible moulds on office

furniture. As such, this study was performed to determine the association between physical

factors and the occurrence of SBS and perception of comfort over thermal condition of

offices. The result of this study can be used to provide recommendation to the management

and can be used as a guide for other researchers in Malaysia.

2.0 Materials and Methods

The cross-sectional study was conducted in the offices of a public research university building

in Selangor. Data collection was performed from 2nd

to 13th

of February, 2015. The

populations of this study were lab staffs, lecturers, and postgraduate students housed in

offices in the laboratory building of the public university.

The total number of respondents required for this study was 175. In total, 180 numbers of

respondents were invited to participate in this study. The respondents were randomly selected

from the list of staffs obtained from the Registrar Office of the public university. Accepted

criteria that enable occupants to take part in this study is that, occupant must be between the

age of 18-50 years old, has worked six month and above and spend 60% of their work time in

their office. Occupants that report respiratory illness or are pregnant were exempted from

participating in this study.

SBS, background information and perception of comfort

A self-administered questionnaire was designed to obtain all information from the

respondents regarding the occurrence of SBS symptoms. The questionnaire was modified

from the Indoor Air Quality and Work Environment Symptoms Survey, NIOSH Indoor Air

Quality Survey (1991). The questionnaires were distributed randomly to 180 occupants. The

questionnaire was also used to collect background information related to the research.

Modified questionnaires were used to obtain information from the respondents regarding their

perception over the thermal condition of their office room in the public university lab

building. The questionnaire was modified from the American Society of Heating,

Refrigerating, and Air-Conditioning Engineers (ASHRAE) Thermal Comfort Questionnaire

(2005). For the occupants’ perception towards the thermal condition of their office room, the

answers were based on 7-point thermal sensation scale by ASHRAE.


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Physical Measurement

TSI 8386 Velocicalc Plus (TSI Incorporated, Shoreview, Minnesota) is used to measure air

temperature, RH, and air velocity of the selected office rooms. In total, there was 19 rooms

selected for this study. The measurement is taken four times a day as recommended by

Malaysia Indoor Air Quality Code of Practice (IAQ, COP) (DOSH, 2010) for a total of 2

weeks (working day). The measurement of the physical factors were taken in the morning (8

am and 11 am), afternoon (2 pm), and evening (5 pm). Three readings were obtained for each

parameter in each point. Three sampling points is taken for each room.

Data Analysis

The data was entered and analyzed using IBM Statistical Package for Social Science (SPSS)

version 22.0 (Chicago). Descriptive analysis was performed to identify for the mean, x2,

minimum and maximum value of the continuous data obtained. Multiple logistic regressions

were performed to identify the factors contributing to the reporting of SBS and perception of

comfort.

3.0 Result

3.1 Socio-demographic distribution

A total of 180 questionnaires were distributed to occupants and 97% (n=175) of the

questionnaires were answered and returned.

Table 1: Result from descriptive analysis of socio-demographic characteristics of respondents

Variables N=175 Mean (standard

deviation)

Range

Gender

Male

Female

26 (14.9)

149 (85.1)

- -

Ethnicity

Malay

Chinese

Indian

157 (89.7)

13 (7.4)

5 (2.9)

- -

Age (years)

18-25

26-35

36-50

26 (52.0)

77 (26.9)

72 (21.1)

32.3 (6.9)

24-48

Type of room

Office room

Shared room

Open space with

partition

Open space without

partition

68 (38.9)

47 (26.9)

36 (20.6)

24 (13.6)

- -


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Smoking status

No

Yes

158 (90.3)

17 (9.7)

- -

History of allergy

No

Yes

164 (93.7)

11 (6.3)

- -

History of chemical

allergy

No

Yes

173 (98.9)

2 (1.1)

- -

Duration of work in a

week (hours)

- 40.2 (2.09) 30-50

Duration working in

the building (years)

- 2.5 (1.3) 0.1-7

From Table 1, there were 85.1% of female respondents compared to males (14.9 %). For

ethnicity, majority of the respondents were of Malay ethnicity, which comprised of 89.7 % of

overall respondents. The average age of the respondents in this study was 32.3±6.9 years old

and has worked for about 2.5 years in the university.

There are four types of offices found at the laboratory building of the public research

university; enclosed single room, shared room, open space with partitions, and open space

without partition. Approximately 40% of the respondents worked in their own office room,

while 27% worked in shared room. Among the respondents, approximately 10% of them were

current smokers. About 6% of the respondents reported a history of allergy with 1.1%

reported the history of chemical allergy.

3.2 Physical measurements of the offices

Table 2: Result of data analysis on physical measurements of the offices

Physical factor n=19 Percentage (%) Mean±Std.

Deviation

Range

Temperature (ºC)

Not Comply

Comply

2

17

10.5

89.5

25.1±0.5

24.3-26.4

Relative Humidity

(RH)%

Not Comply

Comply

4

15

21.0

79.0

69.0±1.2

67.7-71.3

Air Velocity (m/s)

Not Comply

Comply

1

18

5.3

94.7

0.2±0.03

0.1-0.3

Table 2 presents the physical measurements of temperature, RH and air velocity for 19

offices. The average temperature was 25.1±0.5 ºC, while the humidity ranged from minimum

of 67.7% to maximum of 71.3%. The average air velocity was 0.2±0.03 m/s. The averages

were within the stipulated averages given by the ICOP (DOSH 2010). When compared to the

ICOP, it was found that for temperature, two of the rooms had levels which were not within


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the allowable limits. On the other hand, for RH, 4 out of the 19 rooms were not within the

acceptable range. For air velocity, only 1 of the office was not within the acceptable range as

stipulated by ICOP (DOSH 2010).

3.3 SBS symptoms

Table 3: Result of the reported SBS symptoms among respondents (n=175)

SBS symptomsa No

n (%)

Yes

n (%)

Headache 138 (78.9) 37 (21.1)

Heavy head 151 (86.3) 24 (13.7)

Fatigue 158 (90.3) 17 (9.7)

Sleepy 154 (88.0) 21 (12.0)

Dizzy 173 (98.9) 2 (1.1)

Nausea/vomit 175 (100) 0 (0)

Coughing 172 (98.3) 3 (1.7)

Runny nose 167 (95.4) 8 (4.6)

Sore throat 172 (98.3) 3 (1.7)

Skin rash/Itchy 173 (98.9) 0 (0)

Eye irritation 172 (98.3) 3 (1.7)

Scaly scalp/Itchy 175 (100) 0 (0)

Calculated SBSa 158 (90.3) 17 (9.7)

a SBS is defined as ‘yes’ to two or more symptoms

Table 3 describes the reporting of SBS symptoms among the respondents. Approximately

one-fifth of the respondents reported headache as the highest SBS prevalence. The prevalence

of SBS was 9.7%.

3.3.1 Perception of comfort

Approximately 11% of respondents reported that they were uncomfortable with the thermal

condition of their office room.

3.4 Multiple logistic regressions between physical factors, SBS, and perception

Table 4: Result of multiple logistic regressions between physical factors, SBS, and perception

of comfort

Variables SBS

OR(95%Cl)

Perception of comfort

OR(95%Cl)

Temperature

Comply

Not Comply

1

0.74 (0.07-7.26)

1

10.76 (2.17-53.5)*

Relative Humidity (RH)

Comply

Not Comply

1

4.05 (1.27-12.9)*

1

15.2 (4.28-54.1)*


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Age Category (year)

18-25

26-35

36-50

0.49 (0.85-2.81)

1.25 (0.39-4.00)

1

0.62 (1.08-3.62)

1.36 (0.36-5.14)

1

Gender

Male

Female

1

5.12 (1.5 – 17.3)*

1

6.52 (1.49-28.6)*

Duration of work per week

(hour)

30 - 40

40 – 55

1

0.12 ( 0.007- 2.05)

-

-

Duration of work (year)

< 3

≥ 3

1

0.47 (0.15 – 1.49)

1

0.62 (0.17-2.33)

R2(Nagelkerke) 0.16 0.42

*Significant at p ≤ 0.05

Table 4 shows the results obtained from the multiple logistic regressions. The results from the

multiple logistic regressions shows that RH (OR=4.05, 95% CI=1.27-12.9) and the female

gender (OR=5.12, 95% CI=1.5-17.3) were significantly linked with the reporting of SBS,

while for perception, temperature (OR=10.76, 95% CI=2.17-53.5), RH (OR=15.2, 95%

CI=4.28-54.1), and the female gender (OR=6.52, 95% CI=1.49-28.6) were significant

contributors.

4.0 Discussion

From this study, the data obtained showed that approximately 10% of the respondents in the

offices of the public research university experienced SBS. Compared to other studies done in

Malaysia, the prevalence of SBS found in the present study is relatively low. Notable studies

referred to was the study by Zamani et al. (2013), in which the prevalence of SBS was 24.9%

(Zamani et al., 2013) and the study by Fadilah and Juliana (2012), in which the SBS was

33.8%. When compared to other studies globally, a study in Italy reported a prevalence of

31.9% (Magnavita, 2015) while another study in Singapore reported a prevalence of 19.4%

(Ooi et al. 1998). In the present study, respondents were considered to have SBS when two or

more questions from the NIOSH Indoor Air Quality Survey were answered in the affirmative.

Compared to other report, SBS is calculated when affirmative answers were given to five or

more questions on SBS symptoms (Magnavita, 2015). It is likely that the various definition of

SBS causes the varying distribution of SBS prevalence.

One study reported that SBS symptoms were influenced by various environmental and non-

environmental variables (Rubin, 1996). Physical factors such as temperature, RH and velocity

are not the only factors found to be linked with the occurrence of SBS. A report by Shaw

(1997) showed that irritants were linked with SBS. As such, to reduce the prevalence of SBS

symptoms among office workers, minimization of the level of indoor air pollutants is

important to effectively remove localized contamination sources through specifying the


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building materials and furnishings with low emission potentials, locating the outdoor-air

intakes away from known outdoor sources, and using special exhaust system (Shaw, 1997).

Temperature, RH, and velocity have been used traditionally to express thermal comfort

(Seppänen et al., 2003). For this study, the range of these parameters for most offices in the

laboratory complex was within the acceptable limit as stipulated by ICOP (DOSH 2010).

There were a number of offices which reported that the temperature, RH and velocity was not

within the required range but the percentages were small. For the type of offices which were

found to have temperature, RH, and velocity outside the acceptable range, further

investigations found that the likely reason was because of the issue in the MVAC system. The

MVAC system for some of the rooms did not have a proper outlet for the air-conditioning

system. These rooms have been recently modified due to the placement of additional member

of staffs. However, the modification were made without proper redesigning of the ventilation

system. Partitions were added without upgrading the ventilation system. In the end, some of

the rooms only had diffuser ducts but did not have working return ducts. Ultimately, this

causes high humidity in such rooms which is believed to have led to the problems with mould

growth.

In Malaysia, there have been such reports of public buildings which have improper MVAC

system and caused IAQ problems (Ismail et al., 2010). It is important that to ensure good

IAQ, employers needs to provide a working MVAC system to comply with the requirements

set out in ICOP. Section 15 of the Occupational Safety and Health Act 1994 has stipulated

that the responsibility of the occupational safety and health lies with the employer (OSHA,

1994). Results from the monitoring of indoor air quality based on the ICOP by DOSH can be

used as an evidence in the court of justice should the health of employees be comprised from

causes arising from the workplace in later years.

This study showed that approximately 11% of the workers reported that they perceive their

working environment as uncomfortable. In a study in China, the researcher concluded that

thermal comfort for an individual not only depends on the environment but also depends on

the individual’s feeling or physiology and psychology (Chen et al., 2005). As such, the

perception of the workers is an important factor to consider in relation to comfort.

The results from the multiple logistic regressions shows that RH (OR=4.05, 95% CI=1.27-

12.9) and the female gender (OR=5.12, 95% CI=1.5-17.3) were significantly linked with the

reporting of SBS. RH is a common indoor exposure, related to an increase of respiratory

symptoms (Pieckova and Zdenka, 1999). In other studies, SBS may be related to personal

factors, such as the female gender (Stenberg and Wall, 1995; Engvall et al., 2001). As in the

present study, it was found that the female gender was more likely to report SBS and did not

have the perception of comfort. The office workers involved in this study consisted of mostly

women. Nevertheless, the study by Stenberg and Wall (1995) found that women usually

reported work-related and environmental symptoms more often than men, which may explain

the relatively high frequencies of complaints among the respondents.

The perception of comfort was significantly contributed by temperature (OR=10.76, 95%

CI=2.17-53.5), RH (OR=15.2, 95% CI=4.28-54.1), and the female gender (OR=6.52, 95%

CI=1.49-28.6). This is in agreement with a previous study performed by Wang et al. (2008),

temperature and humidity affect thermal comfort. Other research showed evidence of an

association between gender and perception of comfort (Karjalainen, 2007). Female shows

more dissatisfaction over the thermal comfort compared to male.


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This study had a few limitations that needs to be considered. This study did not measure the

presence of mould. Increased RH has been frequently associated with the presence of mould.

A previous study has also shown that mould is strongly associated with the occurrence of SBS

(Engvall et al., 2001). Although the number of rooms with parameters that were outside the

range of acceptable RH is minimal, most of the rooms have RH levels close to the upper limit

of the allowable RH range (i.e. 70). A study has shown that mould presence is evident in

indoor spaces with RH levels between 60 to 70% (Saijo et al., 2009). Although not reported in

the results, some of the offices have clear mould problems obvious from the patches of white

spots on the ceiling or furniture. Secondly, this study did not measure all the functions in

determining thermal comfort. Thermal sensation scale, expressed by ASHRAE (2013) as the

predicted mean vote comprised of six variable to represent thermal comfort. In addition to air

temperature, air velocity and air humidity, thermal comfort analysis is inclusive of the

assessment of mean radiant temperature, clothing resistance and activity level or metabolic

rate of the respondents (Hensen, 1990). All these variables are known as Fanger’s comfort

equation and should ideally be taken into account to give a more comprehensive overview of

thermal comfort. Last but not least, the significant results for the association between

temperature and RH with the perception of comfort in the multiple logistic regression needs to

be interpreted with caution. This is due to the large 95%CI upper limit estimation which may

likely be an overestimation of the logistics analysis (James and Savitri, 2005) due to the small

prevalence of the perception of comfort.

5.0 Conclusion and recommendation

The results obtained showed that the prevalence of SBS was 9.7% while for the perception of

comfort, 10.9% of respondents reported discomfort with the thermal condition of their

working area. The results from the multiple logistic regressions shows that RH (OR=4.05,

95% CI=1.27-12.9) and the female gender (OR=5.12, 95% CI=1.5-17.3) contributed

significantly to the reporting of SBS, while for perception, temperature (OR=10.76, 95%

CI=2.17-53.5), RH (OR=15.2, 95% CI=4.28-54.1), and the female gender (OR=6.52, 95%

CI=1.49-28.6) were significant contributors.

Since this study had a high response rate, the results obtained can represent the entire

population of the laboratory staffs being studied in the public research university. This

information can be used as guidance for the management of the public research university to

undertake improvement for the offices. The improvements or control measures should be

carried out to ensure that the occupants of the building are comfortable with their working

environment and also to decrease the prevalence of SBS occurrence among occupants in lab

building of public research university.

Improvements and control measures that can be done by management include improving

ventilation system of the building. The management can ensure that the inlet and outlet

system are installed as such that it functions well in every office rooms. Besides that, monthly

maintenance should be done to make sure that the ventilation system and also the air-

conditioner are well-functioned. The control measures are important to ensure safe and

healthy work environments which are the fundamental rights of the workers.


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Acknowledgement

The authors would like to express gratitude to all the staff and the department at the public

research university which have took part in this study as well as all the respondents who

participated in this research. The ethical approval of this study was obtained from the Ethics

Committee for Research Involving Human Subject, Universiti Putra Malaysia.

Declaration

The Authors declare that there is no conflict of interest.

References

ASHRAE (2004). Standard 55-2004. Thermal environmental conditions for human

occupancy. ASHRAE. Atlanta, USA. Assessed on 31st of May 2015 -

ftp://law.resource.org/pub/us/code/ibr/ashrae.90.1.2004.pdf.

ASHRAE (2013). Standard 55-2013. Thermal environmental conditions for human

occupancy. ASHRAE. Atlanta, USA. Assessed on 31st of May 2015 -

https://www.ashrae.org/resources--publications/bookstore/standard-55.

Chen K., Rys M.J., Lee E.S. (2005). Modelling of thermal comfort in air conditioned rooms

by fuzzy regression analysis. Mathematical and Computer Modelling, 43: 809-819.

DOSH (2010) Industry Code of Practice on Indoor Air Quality, Ministry of Human Resources

Malaysia. Assessed on 31st of May 2015 -

http://www.dosh.gov.my/index.php?option=com_docman&task=doc_download&gid=59

4&Itemid=183.

Engvall, K., Norrby, C., Norbäck, D. (2001). Sick building syndrome in relation to building

dampness in multi-family residential buildings in Stockholm. International Archives of

Occupational and Environmental Health, 74, 270–278.

Fadilah, R. N., Juliana, J. (2012). Indoor Air Quality (IAQ) and Sick Buildings Syndrome

(SBS) among Office Workers in New and Old Building in University. Health and the

Environment Journal, 3(2), 98–109.

Groth, A. (2007). Energy Efficiency Building Design Guidelines for Botswana. Botswana:

Department of Energy, Ministry of Minerals, Energy and Water Resources.

Hensen, J. L. M. (1990). Literature review on thermal comfort in transient conditions.

Buildings and Environment, 25(4), 309-316.

http://www.dosh.gov.my/index.php?option=com_docman&task=doc_download&gid=594&Itemid=183

http://www.dosh.gov.my/index.php?option=com_docman&task=doc_download&gid=594&Itemid=183


May/June 2015


IJPHCS


Institute of Medicine (2004). Damp indoor spaces and health. Washington, DC: National

Academies Press.

Ismail, M., Sofian, M., Zafirah, N., Abdullah, A. M. (2010). Indoor air quality in selected

samples of primary schools in Kuala Terengganu, Malaysia. Environment Asia, 3(103),

108-231.

James, R. C., Savitri, A. (2005). Statistical analysis of survey data In: Household Sample

Surveys in Developing and Transition Countries. Brogan D. United Nations

Publications, pp. 8.

Jones, A.P. (1999). Indoor air quality and health. Atmospheric Environment, 33(28), 4535-

4564.

Karjalainen, S. (2007). Gender differences in thermal comfort and use of thermostats in

everyday thermal environments. Building and Environment, 42, 1594–1603.

Magnavita, N. (2015).Work-related symptoms in indoor environments: a puzzling problem

for the occupational physician. International Archieves of Occupational and

Environmental Health, 88(2), 185–196.

Marmot, A. F., Eley, J., Stafford, M., Stansfeld, S. A., Warwick, E., Marmot, M. G. (2006).

Building health: an epidemiological study of “sick building syndrome” in the Whitehall

II study. Occupational and Environmental Medicine, 63(4), 283-289.

Mendell, M. J., Mirer, A. G. (2009) Indoor thermal factors and symptoms in office workers:

findings from the US EPA BASE study. Indoor Air, 19(4). 365-368.

Mi, Y. H., Norbäck, D., Tao, J., Mi, Y. L., Ferm, M. (2006). Current asthma and respiratory

symptoms among pupils in Shanghai, China: influence of building ventilation, nitrogen

dioxide, ozone, and formaldehyde in classrooms. Indoor air, 16(6), 454-464.

Ooi, P. L., Goh, K. T., Phoon, M. H., Foo, S. C., Yap, H. M. (1998). Epidemiology of sick

building syndrome and its associated risk factors in Singapore. Occupational and

Environmental Medicine, 55(3), 188–193.

OSHA (1994). Occupational Safety & Health Act (514) Malaysia.

Pieckova, E., Zdenka, J. (1999). Microscopic fungi in dwellings and their health implications

in humans. Annals of Agricultural and Environmental Medicine, 6, 120-128.

Saijo, Y., Nakagi, Y., Ito, T., Sugioka, Y., Endo, H., Yoshida, T. (2009). Relation of

dampness to sick building syndrome in Japanese public apartment houses.

Environmental Health and Preventive Medicine, 14, 26–35

Sarafis, P., Sotiriadou, K., Dallas, D., Stavrakakis, P., Chalaris, M. (2010). Sick-building

syndrome. Journal of Environmental Protection and Ecology, 11, 515–522.


May/June 2015


IJPHCS


Seppänen, O., Fisk, W. J. (2006). Some quantitative relations between indoor environmental

quality and work performance or health. International Journal of HVACR Research,

12(4), 957-973.

Seppänen, O., Fisk, W.J., & Faulkner, D. (2003). Cost benefit analysis of the night-time

ventilation cooling. Proceedings of the Healthy Buildings 2003 Conference, 3, 394-

399.

Shaw, C.Y. (1997). Construction technology update No. 3: Maintaining acceptable air quality

in office buildings through ventilation. National Research Council’s Institute for

Research in Construction, 16, 617-811.

Stenberg, B., Wall, S. (1995). Why do women report “sick building symptoms” more often

than men? Social Science Medicine, 40, 491-502.

Wang, B. L., Takigawa, T., Yamasaki, Y., Sakano, N., Wang, D. H., Ogino, K. (2008).

Symptom definitions for SBS (sick building syndrome) in residential dwellings.

International Journal of Hygiene and Environmental Health, 211, 114–120.

Zamani, M. E., Jalaludin, J., Shaharom, N. (2013). Indoor air quality and prevalence of sick

building syndrome among office workers in two different offices in Selangor. American

Journal of Applied Sciences, 10(10), 1140–1147.

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