Exposure to second-hand smoke among secondary school-going adolescents: Findings from the Malaysian Adolescent Health Risk Behaviour (MyAHRB) study

Abstract

Background:

Exposure to second-hand smoke (SHS) is one of the main causes of morbidity and it has been proven to be associated with an increased likelihood of smoking initiation among adolescents. Nonetheless, evidence on SHS exposure among Malaysian adolescents is scarce. Therefore, this article aims to demonstrate the magnitude and factors associated with SHS exposure among school-going adolescents in selected secondary schools in Peninsular Malaysia.

Methods:

Data were derived from the Malaysian Adolescent Health Risk Behaviour (MyAHRB) study conducted in 2013. A total of 2599 adolescent were recruited into the study using a two-stage proportionate-to-size sampling method. Data were obtained from self-administered questionnaires. Descriptive analysis and multivariable logistic regression were performed to determine the risk factors/predictors associated with SHS.

Results:

More than half of the respondents had been exposed to SHS during the last one week (56.4%), and SHS exposure was significantly higher among respondents who smoked (94.0% vs. 49.9%, p <0.001). Multivariable analysis revealed that the likelihood of exposure to SHS was higher among those who smoked (adjusted odds ratio (aOR) 12.90, 95% confidence interval (CI): 8.01–20.4), had at least one parent/guardian who smoked (aOR 5.49, 95% CI: 4.41–6.94) and adolescents of Malay descent (aOR 2.10, 95% CI: 1.68–2.63).

Conclusion:

Our findings suggested that the effectiveness of anti-smoking measures implemented in recent years to protect adolescents from the health risks of passive smoking were less evident. Therefore, educational and awareness programmes that emphasize the negative health impacts of SHS exposure on Malaysian adolescents, particularly when among smoking adults, should be intensified to help in preventing adoption of smoking behaviours among adolescents.

Keywords

Second-hand smoke school-going adolescents smoking MyAHRB health risk behaviour

Introduction

Second-hand smoke (SHS) comprises mainstream smoke (the smoke exhaled by the smoker) and sidestream smoke (the smoke released from the burning end of a cigarette).¹ It contains various chemical elements, 250 of which have been identified as toxic and 50 as carcinogenic.² Ample scientific investigations have demonstrated that SHS exposure is associated with increased morbidity and mortality.^3,4 As many as 603,000 premature deaths and loss of 10.9 million disability-adjusted life years in 2004⁵ were caused by diseases related to SHS exposure globally. A large portion of estimated deaths was attributable to SHS-related diseases such as ischaemic heart disease, lower respiratory infections in children and asthma in adults.⁵ Studies have also revealed that exposure to SHS increased the risk of childhood morbidities, including acute respiratory infections, middle ear disease, asthma exacerbation, respiratory symptoms and decreased lung function.^6–10 Furthermore, the causal effects of cancer and cardiovascular disease with SHS exposure among adults have also been reported.¹¹ From the behavioural aspect, SHS exposure has also increased the likelihood of susceptibility to smoking¹² and smoking initiation among adolescents.^13–15 A systematic review by Chen and colleagues of 15 studies had found an inverse relationship between neurodevelopment and SHS exposure, which led to unsatisfactory academic achievement.¹⁶ Similarly, a study conducted by Abidin and colleagues¹⁷ among 370 school-going adolescents aged 13–14 years from 18 selected secondary schools in Kuala Lumpur and Negeri Sembilan, Malaysia has also demonstrated that adolescents who were exposed to SHS during toddlerhood were three times more likely to have lower cognition compared with those without SHS exposure.

The proven harmful effects of SHS exposure have prompted health authorities from various countries to introduce policies in order to reduce the burden of disease attributable to SHS. Measures such as health promotion activities and introduction of smoke-free areas in various public places have been implemented in many countries, including Malaysia. The reduction of SHS has been stipulated as one of the target goals in the national anti-smoking strategic plan. Various measures have been initiated and implemented to achieve the goal, namely, the healthy lifestyle campaign since 1990 and gazettement of smoke-free areas, which has been expanded through the provision and amendment of Control of Tobacco Product Regulation 2004.^18,19 Up to 2016, 38 public areas had been gazetted as smoke free areas. In addition, community interventional programmes such as KOSPEN, which focused on promotion of healthy lifestyle behaviours (including anti-smoking), have been implemented in selected localities to serve as a tool to reduce SHS exposure by advocating the concept of a smoke-free home environment among the community members involved in the programme.²⁰

Surveying at a global level revealed that 40% of children and adolescents were exposed to SHS⁵ and the level of exposure was relatively higher among adolescents from non-intact families,²¹ with parents^22–25 or peers who smoked,²⁵ from a lower level income bracket,²¹ and with parents with lower educational attainment²⁶ and a lower level of knowledge on health hazards of SHS.^22,27 However, investigations on the level of exposure to SHS and its associated factors among adolescents were not given due attention in Malaysia. The focuses of Malaysian investigators or researchers during the last three decades were mainly on prevalence of and factors associated with smoking among adolescents.^28–31 Furthermore, despite there being attempts to investigate SHS exposure, such studies only targeted Malaysian adults aged 18 years and above^32,33 and, due to the differences in smoking prevalence, societal pattern, behavioral aspect and economic status, the generalization of those findings to the adolescent subpopulation is inappropriate. Therefore, investigation of SHS exposure among adolescents is urgently needed to address the existing knowledge gaps. As such, the aim of this article is to describe the prevalence and factors associated with SHS exposure among school-going adolescents in Peninsular Malaysia.

Methods

The Malaysian Adolescent Health Risk Behaviour (MyAHRB) study was a cross-sectional study conducted in 2013. A two-stage proportionate-to-size sampling method was used to select a representative sample of school-going adolescents. The first stage involved the selection of districts with Clinical Training Centres (CTCs) for public health paramedics; every state in Peninsular Malaysia has at least one CTC (some states, such as Kedah and Johor, have two CTCs), while the second stage involved sampling stratification by locality (urban or rural and urban) in the selected districts. Subsequently, one school was selected from an urban and a rural area, respectively, for all selected districts via a simple random sampling method. Overall, a total of 40 secondary schools was selected for the study (20 schools from urban and 20 from rural areas). A detailed description of the MyAHRB study is available in a report of the MyAHRB study.³⁴ The Ministry of Education, Malaysia and the respective State Education Department had approved the study. Ethical approval was granted by the Medical Research Ethics Committee, Ministry of Health Malaysia.

Data were collected from the students via self-administered questionnaires. Prior to the study, informed consent was obtained from the parents/guardians of selected students. During the data collection day, respondents were briefed by the research team members on the aims of the study and each item in the questionnaire. The research team had also ensured that no school staff or teachers were present during the data collection session to reduce the Hawthorne effect.

Measures

The study instrument was adapted from the Global School-based Student Health Survey³⁵ and the Youth Risk Behaviour Surveillance³⁶ questionnaires, which included items on smoking and SHS. The questionnaire was forward translated to the Malay language and backward translated to the English language by different groups of content and language experts. The questionnaire was pre-tested among secondary school students in Kuala Lumpur to establish face validity. Minor corrections and modifications were made accordingly.

The final questionnaire consisted of several sections, namely social demographic (gender, age group, ethnicity, parental marital and educational status, type of occupation, academic performance), health risk behaviour (smoking, physical activity, sexual behaviour, alcohol consumption, vegetable/fruit intake, violent behaviour, physical fighting), protective factors (connectedness with parents, having peers who are helpful), Rosenberg self-esteem scale, religiosity and feelings of loneliness.

For the present study, the dependent variable ‘exposure to SHS’ was measured using the item ‘In the last 7 days, how often people smoking in front of you?’. Respondents who answered ‘every day’, ‘1–2 times a week’, ‘3–4 times a week’ and ‘5–6 times a week’ were classified as ‘exposed to SHS’, whereas those who answered ‘no one smoke in front of me during the last one week’ were categorized as ‘not exposed to SHS’.

Data analysis

SPSS statistical software version 20 was used in the data analysis. Descriptive statistics were used to describe the socio-demographic characteristics of the respondents and exposure to SHS during the last one week of the survey. The association between exposure to SHS and all categorical independent variables was analysed using the chi-squared test. The independent variables were smoking status (current smoker, non-smoker), parents/guardian who smoked, gender, ethnicity (Malay, Chinese, Indian, other ethnicities), age, parental marital status (married, divorced) and parental educational attainment (no schooling, primary school, secondary school, tertiary education). Independent variables with p value less or equal to 0.25 in the univariate analysis (chi-squared test) were included in a multivariable logistic regression model to adjust for possible confounding effects of other independent variables investigated in this study. In the multivariable logistic regression, Chinese, Indian and other ethnicities were combined as ‘non-Malay’ due to the smaller proportion of respondents. The two-way interaction between independent variables in the final model was also examined and no significant interaction was detected (p >0.05 for all two-way analyses). The Hosmer–Lemeshow goodness-of-fit test indicated the model had good fit (p=0.775). All statistical analyses were performed at 95% confidence level.

Results

The study achieved a response rate of 73.6% (n= 2634/3577). Gender composition was 51.9% (n=1366) females and 48.1% (n= 1268) males. Almost 80% of the respondents were Malays, followed by Chinese (13.5%). Most of them were Form-4 students (16 years old) (91.5%) while the remaining 8.5% were Form-5 students (17 years old). A total of 14.9% (n= 387) of the respondents were current smokers (Table 1).

Table 1.

Social demographic characteristic of school going adolescents in selected secondary schools in Peninsular Malaysia.

Variable	n	%
Gender
Male	1268	48.1
Female	1366	51.9
Ethnicity
Malay	2091	79.4
Chinese	355	13.5
Indian	177	6.7
Others	11	0.4
Form
Form 4	2379	91.5
Form 5	231	8.85
Father education attainment
No formal education	54	2.1
Primary	218	8.5
Secondary	1515	59.4
Tertiary	763	29.9
Mother education attainment
No formal education	56	2.2
Primary	230	9.0
Secondary	1668	65.2
Tertiary	604	23.6
Family status
Intact	2465	94.6
Single parent family	142	5.4
Smoking status
Smoker	387	14.9
Non-smoker	2216	85.1
At least one parent/guardian smokes
Yes	740	29.6
No	1756	70.4

Table 2 shows that the prevalence of exposure to SHS was 56.4% (95% confidence interval (CI): 53.3–59.5) and this was almost two times higher among smokers compared with non-smokers (94.0% vs. 49.9%, p <0.001) and respondents who had parent/s or guardian/s who smoked (82.1% vs. 44.6%, p <0.001). SHS exposure was also significantly higher among males, and those of Malay descent.

Table 2.

Prevalence of SHS exposure among school going adolescents in selected secondary schools in Peninsular Malaysia.

Variable	Overall
	Exposed to SHS		Chi-squared value	p-value
	Yesn (%)	Non (%)
Overall	1467 (56.4)	1132 (43.6)
Gender
Male	776 (62.3)	469 (37.7)	33.66	<0.001
Female	691 (51.0)	663 (49.0)
Ethnicity
Malay	1269 (61.5)	796 (38.5)	107.83	0.001
Chinese	119 (34.5)	228 (68.7)
Indian	72 (40.9)	104 (59.1)
Others	7 (63.6)	4 (36.4)
Form
Form 4	1314 (56.0)	1033 (44.0)	2.25	0.13
Form 5	140 (61.1)	89 (38.9)
Father education attainment
No formal education	36 (66.7)	18 (33.3)	3.54	0.32
Primary	114 (52.8)	102 (47.2)
Secondary	838 (56.0)	659 (44.0)
Tertiary	204 (57.0)	154 (43.0)
Mother education attainment
No formal education	35 (62.5)	21 (37.5)	2.85	0.42
Primary	123 (54.4)	103 (45.6)
Secondary	923 (56.0)	726 (44.0)
Tertiary	181 (59.9)	121 (40.1)
Family status
Intact	1371 (56.3)	1063 (43.7)	0.20	0.65
Single parent family	81 (58.3)	58 (41.7)
Smoking status
Smoker	360 (94.0)	23 (6.0)	257.82	<0.001
Non-smoker	1105 (49.9)	1108 (50.1)
At least one parent/guardian smokes
Yes	607 (82.1)	132 (17.9)	296.3	<0.001
No	781 (44.6)	969 (55.4)

Multivariable logistic regression analysis revealed that the odds of SHS exposure were significantly higher among smokers (adjusted odds ratio (aOR) 12.9, 95% CI: 8.01–20.8), those who had parent(s)/guardian(s) who smoked (aOR 5.49, 95% CI:4.41–6.94) and those of Malay descent (aOR 2.10, 95% CI:1.68–2.63) (Table 3).

Table 3.

Factors related to SHS exposure among adolescents using multivariable logistic regression analysis.

Variable	MLR analysis
	Crude OR	95% CI		Adjusted OR	95% CI
		Lower	Upper		Lower	Upper
Gender
Male	1.59	1.36	1.86	1.20	0.99	1.45
Female	Ref.			Ref.
Ethnicity
Malay	2.71	2.22	3.29	2.10	1.68	2.63
No Malay	Ref.			Ref.
Form
Form 4	Ref.			Ref.
Form 5	1.24	0.94	1.63	1.28	0.93	1.79
Smoking status
Smoker	15.70	10.21	24.13	12.90	8.01	20.8
Non-smoker	Ref.			Ref.
At least one parent/guardian smokes
Yes	5.71	4.62	7.04	5.49	4.41	6.94
No	Ref.			Ref.

Hosmer Lemeshow–chi-squared value 3.26 (df 6), p=0.775.

Negelkerke R squared 0.297.

MLR: multivariable logistic regression; OR: odds ratio; CI: confidence interval; Ref.: reference.

Discussion

The present study was, to the best of the authors’ knowledge, the first study to demonstrate the prevalence and factors associated with exposure of SHS among secondary school-going adolescents in Malaysia. The present study revealed that more than half of the respondents had been exposed to SHS one week prior to the study, which indicated a moderate to high SHS exposure level.²⁵ This proportion was notably higher compared with the global average proportion of 40%,⁵ the Nigerian proportion of 43%³⁷ and the German proportion of 18.8%.²⁶ In contrast, it was relatively lower compared with Cambodian (67.1% (95% CI: 64.0–70.0) in males and 67.4% (95% CI: 64.2–70.5) in females)³⁸ and Mongolian adolescents (73.9% (95% CI: 71.6–76.1) in males and 71.7% (95% CI: 69.7–73.7) in females).³⁹ Nonetheless, the present finding was comparable to those reported by Abidin et al.¹⁷ and Lappos et al.,⁴⁰ who reported SHS exposure among 52.9% of Malaysian school children and 59.1% of adolescents aged 12–18 years in Greece, respectively. The varied proportions of SHS exposure among adolescents could be attributable to the known variation of sociodemographics, prevalence of smoking among adults and adolescents, community norm towards tobacco use and governmental legislation on smoking between different countries.

Respondents with parent(s) or guardian(s) who smoked were shown to be more likely to be exposed to SHS in both univariate and multivariable analyses. These findings were in agreement with those reported by Peltzer²³ among adolescents aged 11–18 years in South Africa (aOR 5.76, 95% CI: 4.12–8.04), Hwang and Park⁴¹ among a nationally representative sample of adolescents in Korea (aOR 9.95, 95% CI: 9.51–10.47) and Bird et al.⁴² among adolescents in Mexico at home (aOR 4.95, 95% CI: 2.25–7.21) and at places outside the home (aOR 3.91, 95% CI: 2.05–5.96). In addition, the Global Youth Tobacco Survey of 168 countries had also demonstrated a higher likelihood of SHS exposure, both outside and inside the home, among adolescents with smoking parents as compared with their counterparts who did not have parents who smoked.⁴³ Such associations can be due to the plausible reason that if a parent smokes, especially at home, it is unlikely that other house members or their spouse will dissuade them, although they disapprove of smoking behaviour at home, for the sake of family harmony,^44,45 and more so if the smoker is the head of the family, elderly or male. This phenomenon is especially pertinent in Malaysian households in which elderly or males generally have high social status and the sense of respect may deter household members or a spouse from asking them to smoke at another suitable location.⁴⁵

Besides a higher propensity of SHS exposure among respondents who had smoking parent(s) or guardian(s), respondents who smoked also had a higher likelihood of SHS exposure. The present findings concurred with those reported by Rudatsikira and colleagues (2008)³⁸ and Bird et al. (2006)⁴² among adolescents in Cambodia and Mexico, respectively. Adolescents who smoke tend to befriend peers with similar behaviours, including smoking, and share their behaviour of smoking together, as substantiated by Lim and colleagues that 90% of smokers smoked together with their friends.³⁰

However, there was no significant difference in SHS exposure among male and female adolescents and these findings were in line with those demonstrated by Rudatsikira et al.³⁸ Preston et al.⁴⁶ and Peltzer²³ among adolescents in Cambodia, Puerto Rica and South Africa, respectively. On the contrary, investigators from Greece, the USA and Taiwan reported that female adolescents were less exposed to SHS than males.^47–49 These contrary findings could be possibly due to the difference in the prevalence of smoking among adolescents across different countries.

In addition, the present findings also revealed that the age of the respondents (a proxy generated from the Form or Grade) was not associated with SHS exposure. This finding was not in line with those reported by Rudatsikira et al.,³⁸ Rudatsikira et al.,³⁹ and Li and Wang,⁴⁷ who demonstrated a positive relationship between SHS exposure and age among Cambodians, Mongolians and Taiwanese, respectively, either at home or outside the home. A lower smoking prevalence and less established social network with peers among the younger respondents of 11–13 years old may be the plausible reasons for lesser SHS exposure as compared with their older counterparts.⁴¹ However, it should be noted that the target populations in these studies were adolescents aged 11–18 years as compared with those in the present study (16–17 years old). Therefore, it is logical that the magnitude of difference in SHS exposure in the present study was smaller as compared with the previous studies, which had a relatively wider age range. Nonetheless, future investigations are strongly recommended to confirm these hypotheses.

The higher likelihood of SHS exposure among the Malay respondents compared with the non-Malay respondents could in part be due to a higher prevalence of smoking among the Malay adults and thus household members who lived with smoker(s) were more likely to be exposed to SHS.^32,50,51 Another plausible reason is that the Malay respondents might less inclined to dissuade their visiting guests from smoking in their homes compared with other ethnicities. However, future studies investigating the cultural aspects of smoking restriction among different ethnicities in Malaysia should be conducted to elucidate the actual association between ethnicity, cultural background and SHS exposure.

On the other hand, educational attainment, which was considered as a proxy to socioeconomic status, was found to be negatively associated with SHS exposure among adolescents in previous studies.²⁶ However, the present study did not find any association between educational attainment and SHS exposure. Previous studies annotated that respondents of higher educational attainment or socioeconomic status would take better care of their health, such as by not smoking, and were aware of the harmful effects of SHS exposure.⁵² The authors surmised that the insignificant association of educational attainment and SHS exposure may be partly due to the fact that educational attainment may not be positively associated with health awareness among the Malaysian population, particularly on SHS. Therefore, the harmful effects of SHS exposure on health may be overlooked by the community. Rigorous awareness campaigns should be held on a regular basis in order to educate the public, especially among the smoking parents/guardians. Recognition of the harmful effects of SHS on children has been reported to decrease their SHS exposure rates by one-third and substantially improved the health of non-smoking adolescents who lived with smoking adults.⁴²

Limitations

Though with a high response rate, the present study was subjected to a few limitations. First, the self-reported SHS exposure without validation of biological specimens, such as salivary or serum cotinine, may introduce recall bias and result in over-reporting or under-reporting of SHS exposure. Second, independent variables such as knowledge of SHS hazards, the extent of restriction of smoking at home (total restriction, partial or no restriction) and peers’ smoking status, which had been shown as significant variables in previous studies,^37,38,41,53 were not measured in the present study.

Conclusion and recommendation

In conclusion, the present study demonstrated that more than half of Malaysian adolescents of school-going age were exposed to SHS. These findings suggest that specially tailored public health policies and measures such as health promotion activities to create and increase awareness of the adverse health hazards of smoking as well as voluntary smoking restrictions at home are greatly warranted. In addition, implementation of community-based intervention programmes such as the KOSPEN (Komuniti Sihat, Pembina Negara – Healthy Community, Nation Builder) programme of the Ministry of Health Malaysia should be advocated to provide support and direction for those who have difficulty in enforcing smoking restrictions at their homes. These measures would ultimately reduce the SHS exposure among adolescents at home.

Footnotes

Acknowledgements

We would like to thank the Director-General of Health Malaysia for his permission to publish this paper. We would also like to thank the staff of Allied Health College, Sungai Buloh, Selangor who have assisted in data collection.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Availability of data and materials

Please contact corresponding author for data requests.

Authors’ contributions

LHL and LKH wrote the manuscript. SMG, KCC, and TCH carried out statistical analysis. SP and KCC designed the study and for did data collection, and coordination of the study. LHL, LKH, and SMG managed and cleaned the data. TCH, SP, and LHL were involved in interpretation and implications of the analysis. All authors contributed to developing the manuscript, and read and approved the final version.

Declaration of conflicting interests

None declared.

Ethical approval

Ethical approval for the study was granted by Medical Research and Ethical Committee, Ministry of Health Malaysia.

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