The Effect of Ventilation by Window Opening on Stress, Anxiety, and Depression of Female High School Students

Abstract

Background: The mental and physical comfort of students in the classroom is very important because it affects students’ learning. The structure of negative emotional states, including stress, anxiety, and depression is influenced by the building environment and its physical features.
Objectives: The present study aimed to survey the relationship between ventilation by window opening and female student’s stress, anxiety, and depression in high school classrooms.
Methods: The current study was conducted as a quasi-experimental method, using pre-test and post-test with the control group. Statistical population of this study was female students studying at Shiraz high schools during 2016 - 2017. A total of 384 students were selected randomly using Cochran’s formula for participation in the study. The students in 14 classrooms were divided into two groups of intervention and control. The pre-test was used for assessing stress, anxiety, and depression in DASS-21 questionnaires. The intervention group was then allowed to improve the air quality for 6 weeks by opening the window in the classroom. However, this discretion was not given to students in the control group. After 6 weeks of post-test, DASS 21 questionnaire was used.
Results: The mean stress score in the intervention group was 20.36 ± 4.326 at pre-test and 19.91 ± 5.162 at post-test and in the control group was 20.28 ± 5.348 at pre-test and 19.91 ± 5.162 at post-test. The mean anxiety score in the intervention group was 20.15 ± 4.705 at pre-test and 18.55 ± 4.673 at post-test and in the control group was 19.12 ± 5.272 at pre-test and 18.92 ± 5.0 at post-test. Also, the mean depression score in the intervention group was 18.29 ± 4.878 at pre-test and 18.53 ± 4.750 at post-test and in the control group was 17.83 ± 5.501 at pre-test and 17.28 ± 5.375 at post-test. Ventilation by window opening could significantly decrease the level of stress (P < 0.001) and anxiety (P < 0.001) but no significant difference was observed in depression (P = 0.067).
Conclusions: Ventilation by window opening in the classroom could reduce the stress and anxiety of female high school students in eight weeks, but did not affect the level of depression.

Full text

Int J School Health. 2019 April; 6(2):e87038.
Published online 2019 April 8.
doi: 10.5812/intjsh.87038.
Research Article
The Effect of Ventilation by Window Opening on Stress, Anxiety, and
Depression of Female High School Students
Najmeh Najafi 1, Khosro Movahed 1, *, Zahra Barzegar 1and Siamak Samani2
1Department of Architecture, Shiraz Branch, Islamic Azad University, Shiraz, Iran
2Department of Psychology, Shiraz Branch, Islamic Azad University, Shiraz, Iran
*Corresponding author: Department of Architecture, Shiraz Branch, Islamic Azad University,Shiraz, Iran. Tel: +98-9171180077, Email: kmovahed@iaushiraz.ac.ir
Received 2018 December 03; Revised 2019 February 08; Accepted 2019 February 14.
Abstract
Background: The mental and physical comfort of students in the classroom is very important because it affects students’ learning.
The structure of negative emotional states, including stress, anxiety, and depression is influenced by the building environment and
its physical features.
Objectives: The present study aimed to survey the relationship between ventilation by window opening and female student’s stress,
anxiety, and depression in high school classrooms.
Methods: The current study was conducted as a quasi-experimental method, using pre-test and post-test with the control group.
Statistical population of this study was female students studying at Shiraz high schools during 2016 - 2017. A total of 384 students
were selected randomly using Cochran’s formula for participation in the study. The students in 14 classrooms were divided into two
groups of intervention and control. The pre-test was used for assessing stress, anxiety, and depression in DASS-21 questionnaires.
The intervention group was then allowed to improve the air quality for 6 weeks by opening the window in the classroom. However,
this discretion was not given to students in the control group. After 6 weeks of post-test, DASS 21 questionnaire was used.
Results: The mean stress score in the intervention group was 20.36 ±4.326 at pre-test and 19.91 ±5.162 at post-test and in the control
group was 20.28 ±5.348 at pre-test and 19.91 ±5.162 at post-test. The mean anxiety score in the intervention group was 20.15 ±4.705
at pre-test and 18.55 ±4.673 at post-test and in the control group was 19.12 ±5.272 at pre-test and 18.92 ±5.0 at post-test. Also, the
mean depression score in the intervention group was 18.29 ±4.878 at pre-test and 18.53 ±4.750 at post-test and in the control group
was 17.83 ±5.501 at pre-test and 17.28 ±5.375 at post-test. Ventilation by window opening could significantly decrease the level of
stress (P < 0.001) and anxiety (P < 0.001) but no significant difference was observed in depression (P = 0.067).
Conclusions: Ventilation by window opening in the classroom could reduce the stress and anxiety of female high school students
in eight weeks, but did not affect the level of depression.
Keywords: Window Opening, Ventilation, Air Quality, CO2Concentration, Anxiety, Depression, High School, Classroom, Students
1. Background
Mental disorders have increased exponentially in re-
cent decades and led to serious public health problems (1).
In particular, the prevalence of behavioral and mental dis-
orders among high school students has been reported in
several studies (2-5). Students’ mental health is an impor-
tant concern since it affects many factors such as academic
performance, concentration, fatigue, learning, and absen-
teeism (6). For this reason, the identification of factors af-
fecting the development and increase of these disorders is
of interest to mental health researchers.
Stress, anxiety, and depression are negative emotions
that are prevalent among students. Negative emotions not
only have negative effects on mental health but also affect
students’ academic achievements. The World Health Orga-
nization (WHO) reported that depression affects people of
all ages and lifestyle and causes distress and interferes with
a person’s performance at quotidian tasks (7).
The importance of negative side effects related to
stress, anxiety, and depression necessitates the investiga-
tion of this issue among students (8).
Several economic, social, and physical environmental
factors influence human mental health that building envi-
ronment is one of them. The physical environment affects
negative emotions and mental disorders (9). Environmen-
tal psychology helps to identify the factors affecting these
emotions (10). The building environment includes several
determinates such as housing, neighborhood, plants, the
convenience of the facility, and the pattern of land use,
Copyright © 2019, International Journal of School Health. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial
4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the
original work is properly cited.

Najafi N et al.
which affects human mental health individually and col-
lectively. These dimensions affect mental health directly
and the features of the building environment determines
user’s behavior (11). Recent cross-sectional studies in edu-
cational buildings have documented that physical features
of the classrooms and its interior design could affect stu-
dent’s psychological responses such as stress, aggression,
and happiness (12-14).
Several factors might affect the quality of the indoor
environment such as air pollution, noise pollution, visual
contamination, odor, light, air condition quality and ven-
tilation, thermal comfort, and chemical pollutions (15).
Thermal comfort is an environmental feature that af-
fects human mental health (16). Air temperature, relative
humidity, air velocity, clothing, and metabolic rate affect
thermal comfort (17). Although thermal comfort is impor-
tant in all building applications, indoor thermal comfort
is a matter of immense concern for students in the school
as they spend a major portion of their education in the
classrooms (18). A systematic review study showed that
hot weather was one of the factors influencing depression
among students (19).
Human beings use different adaptive opportunities to
control thermal conditions, e.g. opening the windows,
changing clothes, and using curtains. These actions use to
achieve and maintain indoor thermal comfort. Human be-
ings at home or other personal environments adjust their
own thermal environment but public spaces may not be
able to provide all users thermal satisfaction. One effective
solution to reduce indoor air temperature in hot seasons
and improve the air quality is window opening that was
studied in several researches among workers in the offices
or students and staffs in the educational buildings such as
schools and universities (20).
Having self-control in setting thermal environmental
conditions could improve occupant’s tranquility and com-
fort as Zhou and other colleagues (21), indicated in an ex-
perimental study.
2. Objectives
Regarding the importance of the effect of air quality on
mental health, this study seeks to investigate the effect of
ventilation by window opening on negative emotions, in-
cluding stress, anxiety, and depression among female high
school students.
3. Methods
3.1. Study Design and Participants
The method of this study was quasi-experimental de-
sign with pre-test, post-test, and control group. Statistical
population of this study was female students studying at
Shiraz high schools during 2016 - 2017. Cochran’s sample
size formula was used for estimating the sample size (N =
384).
In order to select schools and classrooms, multi-stage
cluster sampling was used. A district was selected ran-
domly from four educational districts of Shiraz. Then,
two schools were selected randomly from all female high
schools in the selected district. In the next step, 14 class-
rooms were randomly selected among the two selected
schools.
In order to have the groups with equal sizes, random
allocation rule was applied to randomize the students. The
students in 14 classrooms were divided into two groups of
intervention (N = 192) and control (N = 192).
By reviewing students’ health records at the school,
students who did not have a specific respiratory disease
participated in the study.
The pre-test was used for assessing stress, anxiety, and
depression in DASS-21 questionnaires. The intervention
group was then allowed to improve the temperature and
ventilation by window opening for 6 weeks in the class-
room. However, this discretion was not given to students
in the control group. After 6 weeks of post-test, DASS-21
questionnaire was used. Intervention process was con-
ducted from April to May 2017.
3.2. Measurement
3.2.1. Depression Anxiety Stress Scale (DASS-21)
DASS-21 was developed by Lovibond and Lovibond and
also has been used widely in clinical samples to screen the
symptoms at different levels of depression, anxiety, and
stress. DASS-21 survey included 21 questions: Depression
(7 states), Anxiety (7 states), and Stress (7 states) self-report
scales that measure these dimensions by 21 states. Answers
were reported on a four-point Likert scale (0 - 3). Response
option from 0 (did not apply to me at all), 1 (applied to me
to some degree, or some of the times), 2 (applied to me to
a considerable degree), 3 (applied to me most of the times)
considered for each state. The higher the score the more
severe emotional distress was (22).
The findings show that the DASS-21 has psychometri-
cally good reliability and validity. Also, the validity of this
questionnaire was investigated by Samani and Joukar (23)
in Iran and reported good internal consistency and con-
struct validity (24).
3.2.2. CO2Concentration
Handheld CO2meter (Carbon Dioxide detector) AZ-
7755 was used to measure CO2concentration. The CO2mea-
suring range is 0 - 9999 (ppm) and the accuracy of the de-
vice is ±50 (ppm) ±5%.
2Int J School Health. 2019; 6(2):e87038.

Najafi N et al.
3.3. Statistical Analysis
Statistical Package for Social Sciences (SPSS) Version
21.0 was used to analyze the data. Mean and standard de-
viation as a descriptive statistical was used to analyze de-
mographic data. Also, the effect of ventilation by window
opening on stress, anxiety, and depression were analyzed
by ANCOVA test.
3.4. Ethical Approval
This article is approved by the Ethics Committee of the
Islamic Azad University. Also, written informed consent
was obtained from the students’ parents.
4. Results
The study sample size consisted of 384 female students
at Shiraz high schools. The mean age of the students in
the intervention group was 17.12 years (SD = 0.54) and in
the control group was 17.41 years (SD = 0.45). All of the
participants (100%) in both groups were educated at the
university. The average of monthly family income in both
groups was between 20 - 30 million Rials. In each group,
none of the students had a history of specific mental ill-
ness. There was no significant difference in the prevalence
of overweight or obesity between the intervention group
(7.1%) and control group (6%).
The mean stress score in the intervention group was
20.36 ±4.326 at pre-test and 19.91 ±5.162 at post-test and
in the control group was 20.28 ±5.348 at pre-test and 19.91
±5.162 at post-test. The mean anxiety score in the interven-
tion group was 20.15 ±4.705 at pre-test and 18.55 ±4.673 at
post-test and in the control group was 19.12 ±5.272 at pre-
test and 18.92 ±5.0 at post-test. Also, the mean depression
score in the intervention group was 18.29 ±4.878 at pre-test
and 18.53 ±4.750 at post-test and in the control group was
17.83 ±5.501 at pre-test and 17.28 ±5.375 at post-test.
In order to investigate the effects of ventilation by win-
dow opening on stress, anxiety, and depression of the stu-
dents, ANCOVA analysis was used. According to the results,
window opening ventilation could significantly decrease
the level of stress (P < 0.001) and anxiety (P < 0.001) but
no significant difference was observed in depression (P =
0.067).
By comparing the CO2concentration, Figure 1 showed
that ventilation by window opening during 6-week inter-
vention significantly improved the classroom indoor air
quality.
5. Discussion
This study aimed to survey the association between
ventilation by window opening and negative emotions,
including stress, anxiety, and depression of female high
school students by studying CO2levels in the classrooms
over six weeks.
Is CO2a good indicator of indoor air quality in class-
rooms? Chatzidiakou and other colleagues answered this
question. Overall, indoor CO2levels were a useful indicator
of indoor investigations (25).
The present study found that by natural ventilation
of the classroom, the temperature was reduced by open-
ing the windows and reached the optimum temperature.
Stress and anxiety were reduced in conditions of natural
ventilation and favorable temperatures, which was consis-
tent with some studies (26-29). According to the finding
of a study conducted in the workplace, good ventilation
and room temperature reduces stress and increases pro-
ductivity in workers (26). Also, chemical elements of the air
manufacturer (such as ozone) and poor ventilation signif-
icantly affected the stress level of females participating in
the study (27). In line with the results of this research, one
of the sources of stress reported among conference inter-
preters in their job setting was poor ventilation as a physi-
cal environmental factor (28). Furthermore, office workers
experienced stress in offices because of sick building syn-
drome, especially poor ventilation (29).
Contrary to the hypothesis, depression was not associ-
ated with ventilation by window opening and temperature
reduction in our population. This finding may in part be a
result of methodological differences between studies, es-
pecially the duration of the intervention that was 6 weeks.
For example, Lan and other colleagues surveyed usual task
work and neuro-behavioral exam during 30°C as a warm
thermal condition and 22°C as a neutral thermal condi-
tion. According to the physiological tests, negative mood
such as depression was reported when the thermal condi-
tion was warm and air quality was undesirable (30).
The predictive models estimated that average indoor
CO2levels during a teaching day should be limited to be-
low 1000 ppm for the coarse fraction and 1200 ppm for the
fine fraction to ensure annual mean exposure below WHO
2010 guidelines. Overall, evidence indicates that limiting
CO2to 1000 ppm, which is lower than current guidelines,
may improve indoor air quality in classrooms (25). Accord-
ing to the present study, CO2levels in the control group was
more than 1200 ppm and below 800 ppm in the interven-
tion group during 6 weeks, which indicated the positive ef-
fect of ventilation by window opening.
There were a number of limitations to the present
study. Due to the fact that Shiraz located in a warm and dry
Int J School Health. 2019; 6(2):e87038. 3

Najafi N et al.
Intervention Group
Control Group
Time (AM)
CO
2
(ppm)
1400
1200
1000
800
600
400
200
0
First Week Second Week Third Week Fourth Week FifthWeek Sixth Week
8 9 10 11 12 8 9 10 11 12 8 9 10 11 12 8 9 10 11 12 8 9 10 11 12 8 9 10 11 12
Figure 1. Indoor CO2concentration during 6 weeks in the intervention and control groups
climate, the need for air ventilation in the warm seasons
is felt more than mild or cold seasons. This study was con-
ducted in April and May, which is the last two months of ed-
ucation in the academic year. However, it is recommended
that the study should be carried out in the warm months
of the year. Maybe the changes in the negative emotions
are more perceptible than the results of the present study.
Also, measuring negative emotions were exclusively self-
reported and might have been affected by self-report bias.
It is recommended that the effect of natural ventilation by
window opening should be investigated on male students
and in other climate areas in future studies.
5.1. Conclusions
According to the results, there is a substantial poten-
tial to reduce indoor pollution levels in the classrooms
with simple cost-effective methods such as ventilation by
window opening. Natural ventilation in the classroom re-
duced female high school student’s stress and anxiety, but
did not affect their depression. It seems that 6 weeks was
not enough time to change the level of depression, and
longer period of time was needed to display the depression
as a common negative emotion among students. Many
schools do not have standardized mechanical air condi-
tioning systems because of the limited funding, and due
to the effects of air ventilation and the appropriate tem-
perature on students’ stress and anxiety, thus it is rec-
ommended to use natural ventilation. The present study
recommended that long-term investigations of pollutants
known to affect health are routinely performed in schools
and when necessary, remedial measures are introduced.
Future studies could examine the effects of natural ventila-
tion and the concentration of CO2in the classroom on aca-
demic performance, learning, fatigue, and other negative
emotions, such as violence among students.
Despite the limitations of school selection and sam-
ple size, findings may assist stakeholders, architects, engi-
neers, and school personnel to take better informed deci-
sions on school building design, retrofitting, and mainte-
nance. Actually indoor air quality investigations in school
buildings should be part of the standard requirements of
building regulations.
Acknowledgments
This article is extracted from the Ph.D. thesis entitled
“Codification a model about effects of thermal comfort on
the behavioral reaction of female high school students”
that was written by the first author under the supervision
4Int J School Health. 2019; 6(2):e87038.

Najafi N et al.
of the second author and the advisory of the third and
fourth authors.
Footnotes
Authors’ Contribution: Najmeh Najafi and Khosro Mova-
hed conceived of the presented idea. Najmeh Najafi
and Siamak Samani performed the analytic calculations.
Khosro Movahed, Zahra Barzegar and Siamak Samani su-
pervised the findings of this work. All authors discussed
the results and contributed to the final manuscript.
Conflict of Interests: The authors declare no conflict of
interests.
Ethical Approval: This article is approved by the Ethics
Committee of the Islamic Azad University.
Funding/Support: Research has been conducted on per-
sonal expenditure.
Patient Consent: Written informed consent was obtained
from students’ parents.
References
1. Nelson B, McGorry PD, Wichers M, Wigman JTW, Hartmann JA. Mov-
ing from static to dynamic models of the onset of mental disorder:
A review.JAMA Psychiatry. 2017;74(5):528–34. doi: 10.1001/jamapsychia-
try.2017.0001. [PubMed: 28355471].
2. Deb S, Strodl E, Sun J. Academic stress, parental pressure, anxiety and
mental health among Indian high school students. Int J Psychol Behav
Sci. 2015;5(1):26–34. doi: 10.5923/j.ijpbs.20150501.04.
3. Dupéré V, Leventhal T, Dion E, Crosnoe R, Archambault I, Janosz M.
Stressors and turning points in high school and dropout: A stress
process, life course framework. Rev Educ Res. 2015;85(4):591–629. doi:
10.3102/0034654314559845.
4. Oberle E, Schonert-Reichl KA. Stress contagion in the classroom?
The link between classroom teacher burnout and morning corti-
sol in elementary school students. Soc Sci Med. 2016;159:30–7. doi:
10.1016/j.socscimed.2016.04.031. [PubMed: 27156042].
5. Li D, Sullivan WC. Impact of views to school landscapes on recovery
from stress and mental fatigue. Landscape Urban Plan. 2016;148:149–
58. doi: 10.1016/j.landurbplan.2015.12.015.
6. Gaillard AW. Concentration, stress and performance. In: Szalma JL,
Hancock PAA, editors. Performance under stress. CRC Press; 2017. p. 75–
92.
7. World Health Organization. Depression and other common mental dis-
orders: Global health estimates. 2017.
8. Doom JR, Haeffel GJ. Teasing apart the effects of cognition, stress,
and depression on health. Am J Health Behav. 2013;37(5):610–9.
doi: 10.5993/AJHB.37.5.4. [PubMed: 23985283]. [PubMed Central:
PMC5860662].
9. Evans GW. Environmental stress. United States of America: CUP Archive;
1984.
10. Gifford R. Environmental psychology: Principles and practice. Colville,
WA: Optimal books; 2007.
11. Firdaus G. Built environment and health outcomes: Identification of
contextual risk factors for mental well-being of older adults. Age Int.
2016;42(1):62–77. doi: 10.1007/s12126-016-9276-0.
12. Najafi N, Movahed K, Barzegar Z, Samani S. The effect of thermal
comfort on stress in female high school students. Int J School Health.
2018;5(3). doi: 10.5812/intjsh.67539.
13. Najafi N, Movahed K, Barzegar Z, Samani S. Environmental factors af-
fecting students’ stress in the educational environment: A case study
of shiraz schools. Int J School Health. 2018;5(2). doi: 10.5812/intjsh.67153.
14. Najafi N, Keshmiri H. The relationship between classroom indoor
plants and happiness of female high school students. Int J School
Health. 2019;6(1). doi: 10.5812/intjsh.82072.
15. Mendell MJ, Heath GA. Do indoor pollutants and thermal conditions
in schools influence student performance? A critical review of the lit-
erature. Indoor Air J. 2005;15:27–32.
16. Coccolo S, Kämpf J, Scartezzini JL, Pearlmutter D. Outdoor hu-
man comfort and thermal stress: A comprehensive review
on models and standards. Urban Climate. 2016;18:33–57. doi:
10.1016/j.uclim.2016.08.004.
17. Fanger PO. Thermal comfort. Analysis and applications in environmental
engineering. Copenhagen: Danish Technical Press; 1970.
18. Zomorodian ZS, Tahsildoost M, Hafezi M. Thermal comfort in ed-
ucational buildings: A review article. Renew Sustain Energy Rev.
2016;59:895–906. doi: 10.1016/j.rser.2016.01.033.
19. Jardim MHDAG, da Silva Junior GB, Silva RB, Alves MLSD, Branco JGDO,
Dos Santos PDS. A systematic review of depression in university stu-
dents. Int J Sci Res. 2018;6(12).
20. Rijal HB, Humphreys MA, Nicol JF. Development of a window opening
algorithm based on adaptive thermal comfort to predict occupant be-
havior in Japanese dwellings. Japan Architect Rev. 2018;1(3):310–21. doi:
10.1002/2475-8876.12043.
21. Zhou X, Ouyang Q, Zhu Y, Feng C, Zhang X. Experimental study of
the influence of anticipated control on human thermal sensation
and thermal comfort. Indoor Air. 2014;24(2):171–7. doi: 10.1111/ina.12067.
[PubMed: 23980928].
22. Lovibond PF, Lovibond SH. The structure of negative emotional
states: comparison of the depression anxiety stress scales (DASS)
with the Beck depression and anxiety inventories. Behav Res Ther.
1995;33(3):335–43. doi: 10.1016/0005-7967(94)00075-U. [PubMed:
7726811].
23. Samani S, Joukar B. [A study on the reliability and validity of the short
form of the depression anxiety stress scale (DASS-21)]. J Soc Sci Hum Shi-
raz Univ. 2007;26(3):65–77. Persian.
24. Asghari A, Saed F, Dibajnia P. Psychometric properties of the depres-
sion anxiety stress scales-21 (DASS-21) in a non-clinical Iranian sample.
Int J Psychol. 2008;2(2):82–102.
25. Chatzidiakou L, Mumovic D, Summerfield A. Is CO2 a good proxy for
indoor air quality in classrooms? Part 1: The interrelationships be-
tween thermal conditions, CO2 levels, ventilation rates and selected
indoor pollutants. Build Serv Eng Res Technol. 2015;36(2):129–61. doi:
10.1177/0143624414566244.
26. Moloney C. Workplace productivity and LEED building. 2012.
27. Fiedler N, Laumbach R, Kelly-McNeil K, Lioy P, Fan ZH, Zhang J,
et al. Health effects of a mixture of indoor air volatile organ-
ics, their ozone oxidation products, and stress. Environ Health Per-
spect. 2005;113(11):1542–8. doi: 10.1289/ehp.8132. [PubMed: 16263509].
[PubMed Central: PMC1310916].
28. Cooper CL, Davies R, Tung RL. Interpreting stress: Sources of job
stress among conference interpreters. J Cross Cult Interlang Commun.
1982;1(2):97–108. doi: 10.1515/mult.1982.1.2.97.
29. Letz GA. Sick building syndrome: Acute illness among office workers-
the role of building ventilation, airborne contaminants and work
stress. Allergy Asthma Proceed. 1990;11(3):109.
30. Lan L, Wargocki P, Wyon DP, Lian Z. Effects of thermal discomfort in
an office on perceived air quality, SBS symptoms, physiological re-
sponses, and human performance. Indoor Air. 2011;21(5):376–90. doi:
10.1111/j.1600-0668.2011.00714.x. [PubMed: 21306437].
Int J School Health. 2019; 6(2):e87038. 5