Exposure to second hand smoke at home and its associated factors findings from the global adult tobacco use survey in vietnam, 2010 (2)

Cancer Causes Control (2012) 23:99–107 DOI 10.1007/s10552-012-9907-z ORIGINAL PAPER Exposure to second-hand smoke at home and its associated factors: findings from the Global Adult Tobacco Use survey in Vietnam, 2010 Hoang Van Minh • Kim Bao Giang • Le Thi Thanh Xuan • Pham Thi Quynh Nga • Phan Thi Hai • Nguyen Thac Minh Nguyen The Quan • Jason Hsia • Received: September 2011 / Accepted: 27 January 2012 / Published online: 29 February 2012 Ó Springer Science+Business Media B.V 2012 Abstract Objective The paper describes the pattern of exposure to second-hand smoke (SHS) at home among the adult population of Vietnam and examines associated socio-demographic factors Methods A total of 11,142 households were selected for this survey using a two-phase sampling design analogous with three-stage stratified cluster sampling The dependent variable was the status of exposure to SHS at home Independent variables included gender, age, occupation, asset-based wealth quintile, ethnicity, marital status, residence Logistic regression modelling was performed to examine the association with relevant factors of patterns of exposure to second-hand smoke among non-smokers Results Of adults aged 15 years and above (representing approximately 47 million people) 73.1% reported they were exposed to SHS at home at least monthly Considering non-smokers only, the prevalence of exposure to SHS at home was 67.6% (equivalent to approximately 33 H Van Minh (&) Á K B Giang Á L T T Xuan Institute for Preventive Medicine and Public Health, Hanoi Medical University, No 1- Ton That Tung, Dong Da, Hanoi, Vietnam e-mail: hvminh71@yahoo.com P T Q Nga World Health Organization Office in Vietnam, Hanoi, Vietnam P T Hai Á N T Minh Vietnam Steering Committee on Smoking and Health (VINACOSH), Hanoi, Vietnam N T Quan General Statistics Office, Hanoi, Vietnam J Hsia Center for Disease Control and Prevention, Atlanta, GA, USA million non-smokers) The significant correlates of the status of exposure to SHS at home among non-smokers were female gender, ethnic minority, low education, and lack of smoking restriction at home Conclusion The study showed that a high percentage of people are exposed to second-hand smoke at home Disadvantaged people were more likely than the better-off to be exposed to SHS at home Keywords Second-hand smoke Á Socio-demographic factors Á Global Adult Tobacco Use survey Á Vietnam Introduction Second-hand smoke (SHS) exposure, also known as ‘‘involuntary smoking’’ or ‘‘passive smoking’’, is nonsmokers’ inhalation of smoke from the exhalation of smokers or from burning cigarettes [1, 2] Evidence of the adverse health effects of exposure to SHS has been accumulating for nearly 50 years [3–5] The U.S Surgeon General estimates that living with a smoker increases a non-smoker’s chances of developing lung cancer by 20–30% [1] Research also suggests that second-hand smoke may increase the risk of breast cancer, nasal sinus cavity cancer, and nasopharyngeal cancer in adults, and leukemia, lymphoma, and brain tumours in children [1, 2, 6, 7] Exposure to second-hand smoke may increase the risk of non-cancerous conditions, for example chronic coughing, phlegm, and wheezing, chest discomfort, severe lower respiratory tract infections, for example bronchitis or pneumonia, and eye and nose irritation [6, 8, 9] Globally, it is estimated that approximately one-third of adults are regularly exposed to second-hand tobacco smoke [10] Second-hand smoke is estimated to cause 123 100 approximately 600,000 premature deaths per year worldwide Of all deaths attributable to second-hand tobacco smoke, 31% occur among children and 64% occurs among women [10] In addition to a large and growing health burden, second-hand smoke exposure also imposes economic burdens on individuals and countries, both the direct costs of health care and indirect costs from reduced productivity Several studies estimate that 10% of total tobacco-related economic costs are attributable to secondhand smoke exposure [11] Although smoking prevalence is decreasing in many high-income countries, it is increasing in many low and middle-income countries [12] As a result, the amount of second-hand smoke and its associated burden of disease are now rising in low and middle-income countries [13] The burden of morbidity from SHS exposure, as measured by disability adjusted life years (DALYs), has been shown to be higher in low-income countries in Southeast Asia and in the eastern Mediterranean region than in Europe [13] Disadvantaged people (especially, women and children) have been suffering more from the burden of disease caused by second-hand smoke [1, 13] In Vietnam, a low-income country in Southeast Asia, smoking is the main form of tobacco use and is very common The prevalence of smoking among those aged 15 years old and over in 2002 was 56.1% among men and 1.8% among women) In 2002, 63% of households had at least one smoker 71% of children under age lived in households with at least one smoker [14] In 2003, nearly 60% school-attending youth reported being exposed to second-hand smoke at home [15] Although the amount of research on tobacco use in Vietnam has recently increased rapidly, there remains a lack of reporting on the pattern of exposure to second-hand smoke among populations The objectives of this paper are to describe the pattern of exposure to second-hand smoke at home among the adult population in Vietnam and to examine its socio-economic correlates This case study provides scientific evidence for policy changes and intervention in Vietnam, and in other low and middle-income countries Methods Data source Data used in this paper were obtained from the Global Adult Tobacco Survey (GATS) conducted in Vietnam in 2010 The GATS is a household survey (using face-to-face interviews) that was launched in February 2007 as a new component of the ongoing Global Tobacco Surveillance System (GTSS) [16] The GATS in Vietnam was designed 123 Cancer Causes Control (2012) 23:99–107 to be a nationally representative survey of all non-institutionalized men and women age 15 and older who considered Vietnam to be their primary place of residence Sample size and sampling A two-phase sampling design analogous to three-stage stratified cluster sampling was used According to the GATS sample design protocol, to obtain reliable estimates of key variables for gender and urban/rural areas 8,000 people are required On the basis of previous similar national household surveys, it was assumed that overall ineligibility and non-response would be 35% After taking the response into account, the final total sample size was 11,142 Half of the enumeration areas (EAs) to be sampled were then assigned to urban and half to rural Because of the different sizes of urban and rural areas, GATS sampled 18 households from each urban EA and 16 households from each rural EA Therefore a total of 657 EAs were sampled to obtain 11,142 households The sample size for EAs was then proportionally allocated across six strata, on the basis of the total number of households In 2009, the General Statistics Office (GSO), Vietnam, conducted a population and housing census The GSO also prepared a 15% master sample to serve as a future national survey sampling framework The 15% master sample contains a subset of EAs that consists of 15% of the population in Vietnam stratified by three groups The first group consists of 132 districts, towns, or cities of provinces The second group consists of 294 plain and coastal districts The third group consists of 256 mountainous and island districts The GATS sample was drawn from the 15% master sample after further stratification of the three groups into urban and rural areas (six strata in total) At the first stage of sampling, the primary sampling unit (PSU) was an enumeration area (EA) The sampling framework was a list of the EAs, from the 15% master sample, with the number of households and identifiable information, administered by the GSO, Vietnam, in 2009 from the census For each of the six strata, the designated number of EAs was selected A selection probability proportional to size (PPS) sampling method was used, where the size was the probability of selection of an EA, using PPS sampling, from the entire target population divided by the probability of selection of an EA for the master sample At the second stage of sampling, 18 households from the selected urban EA and 16 households from the selected rural EA were chosen using simple systematic random sampling One eligible household member from each selected household was then randomly chosen for interview Cancer Causes Control (2012) 23:99–107 Note that this design and the design in which EAs were sampled directly from the universe were analogous The probability of selection of an eligible individual was calculated as the product the of probability of selection for each stage The sampling base weight for an eligible individual was the inverse of the probability of selection shown above Data collection procedure Data collection was done by the GSO, under the cosupervision of the World Health Organization in Vietnam, Vinacosh, and Hanoi Medical University Twenty-six datacollection teams were involved in GATS Vietnam 2010 Each team consisted of one team leader and four interviewers to ensure close supervision and collection of high quality data They had computer skills and previous experience in conducting of GSO household-based surveys, especially GSO health-related surveys In addition to the qualifications needed for interviewers, team leaders for the GATS were experienced in using computers and handheld (iPAQ) devices and had previous experience of working with local authorities Handheld computers were used for capturing data Each interviewer and team leader had one iPAQ A real case file containing addresses and names of the households assigned to the interviewer was preloaded into the iPAQ before the field work All the responses were entered by the interviewer in the iPAQ, with the help of a stylus for touching the key-pad on the screen Data collection was conducted from 22 March 2010 to 13 May 2010 in all 63 provinces of Vietnam Study variables In this work, the dependent variable was the status of exposure to SHS at home The question in the questionnaire was ‘‘What is the frequency of tobacco smoking inside your house (either family members or guests)?’’ Respondents who answered ‘‘daily’’ or ‘‘weekly’’ or ‘‘monthly’’ to the question were classified as people who were exposed to SHS at home Independent variables were gender, age, occupation, asset-based wealth index quintile (this index was constructed by using household assets, utilities, and housing construction as variables in principalcomponents analysis and computing a wealth index for each household), ethnicity, marital status, residence We also included variables on the availability of smoking rules at home and at work, and beliefs of the respondent about the dangers of tobacco smoking and the dangers of secondhand smoke (respondents who believed that breathing other people’s smoke causes serious illness and specific disease in non-smokers, i.e., heart disease in adults, lung illness in 101 children, lung cancer in adults, emphysema, low birth weight, premature birth) Data analysis Both descriptive and analytical statistical analysis was performed using Stata10 software (Stata Corporation) We conducted descriptive analysis of the status of exposure to SHS at home among non-smokers The analytical statistics were used for analysis of the status of exposure to SHS among non-smokers only Multivariate logistic regression modelling was performed to examine the association between patterns of exposure to second-hand smoke among non-smokers and relevant factors The sampling design was fully taken into consideration in the data analysis Weights were used in all computations A significance level of 0.05 was used Results Socio-demographic characteristics of the study population Among the 11,142 sampled households, 10,383 were completely screened, giving a household response of 96.9% The household response was a little higher in rural areas than in urban areas (97.5 and 96.5%, respectively) Overall, only 0.6% of the selected households refused to respond to the survey Among 10,383 individuals selected from the completely screened households, 9,925 were completely interviewed, so the person-level response was 95.7% The person-level response was also a little higher in rural areas than in urban areas (96.3 and 95.0%, respectively) Overall, only 0.6% of the selected individuals refused to respond to the survey In GATS Vietnam 2010, the total response was 92.7% (93.9% in rural areas and 91.7% in urban sites) (Table 1) Table presents sample size and population estimates by selected socio-demographic characteristics The 9,925 completed interviews represented an estimated 64.3 million adults age 15 and over in Vietnam By age group, people age 25-44 made up the largest proportion (41.9%) and those 65 and above accounted for the smallest share (8.8%) Most of the study population reported having lower secondary school education (52.5%) or primary or less education (26.0%) People with a college degree or above made up 7.2% of the study population The main occupation of the study population was Farmer (49.6%), followed by Service/Sales (19.2%), and Production/Driving (12.9%) Other occupations were Manager/Professional (6.6%); Construction/Mining (5.2%); Office workers (2.0%); Forestry/Fishing (1.8%), and others (2.7%) By ethnicity, 123 102 Cancer Causes Control (2012) 23:99–107 Table Number and percentage of households and persons interviewed, and response by residence (unweighted)—GATS Vietnam, 2010 Residence Total Urban Rural Number Percent Number Percent Number Percent Completed (HC) 5,525 92.2 5,158 94.4 10,383 93.2 Completed—No one eligible (HCNE) Incomplete (HINC) 0.0 0.1 0.0 0.0 14 0.0 0.1 No screening respondent (HNS) 0.0 0.0 0.1 Refused (HR) 55 1.0 0.2 64 0.6 Unoccupied (HUO) 216 3.8 166 6.5 382 3.4 Address not a dwelling (HAND) 29 0.5 18 0.2 47 0.4 Other (HO)a 137 2.4 107 0.9 244 2.1 Total households selected 5,670 100 5,472 100 11,142 100 Household response (HR) (%)b 96.5% Selected household 97.5% 96.9% Selected person Completed (PC) 4,958 94.9 4,967 96.3 9,925 95.6 Incomplete (PINC) 0.0 0.1 0.1 Not eligible (PNE) 0.1 0.0 0.1 Refused (PR) 56 1.1 0.2 65 0.6 Incapacitated (PI) 50 1.0 44 0.9 94 0.9 Other (PO) Total number of sampled persons 152 5,225 2.9 100 132 5,158 2.6 100 284 10,383 2.7 100 Person-level response (PR) (%)c 95.0% 96.3% 95.7% Total response (TR) (%)d 91.7% 93.9% 92.7% a a Other includes Nobody Home and any other result code not listed b Calculate Household response (HR) by: HCỵHCNEị100 HCỵHCNEỵHINCỵHNSỵHRỵHO c Calculate Person-level response (PR) by: PC100 PCỵPINCỵPRỵPIỵPO d Calculate Total response (TR) by: (HR x PR)/100 An incomplete household interview (i.e., roster could not be finished) was considered a non-respondent to the GATS Thus, these cases (HINC) were not included in the numerator of the household response A completed person interview (PC) includes respondents who had completed at least question E1 and who provided valid answers to questions B1/B2/B3 Respondents who did not meet these criteria were regarded as incomplete (PINC) non-respondents to GATS and thus, were not included in the numerator of the person-level response 84.5% of the population were Kinh people (the majority) and the remaining 15.5% belonged to other ethnic minority groups By marital status, 67.7% of the population were married, 26.2% were still single, and the remainder (6.2%) were separate/divorce/widow Two-thirds of people age 15 and over in Vietnam were living in rural areas Prevalence of SHS at home In Vietnam in 2010, 73.1% of adults aged 15 years and above (representing approximately 47 million people) reported that they were exposed to SHS at home at least 123 monthly.1 Considering non-smokers only (76.2% of the surveyed population or approximately 49 million people), the prevalence of exposure to SHS at home was 67.6% (equivalent to approximately 33 million non-smokers) Table shows the pattern of SHS exposure at home among the non-smoking population in the past 30 days according to selected socio-economic status The prevalence of exposure to SHS at home among non-smoking males was lower than that among non-smoking females Adults reporting that smoking inside their home occurs daily, weekly, or monthly Cancer Causes Control (2012) 23:99–107 103 Table Distribution of study subjects by selected socio-demographic characteristics—GATS Vietnam, 2010 Characteristic Weighted % Sample size Weighted number Male 4,356 31,258,108 48.6 Female Age 5,569 33,062,657 51.4 15–24 1,656 16,637,021 25.9 25–34 2,053 12,661,740 19.6 35–44 2,198 14,281,840 22.2 45–54 1,867 9,657,483 15.0 55–64 1,019 5,407,631 8.4 1,132 5,675,050 8.8 Gender [64 Education – Primary 2,034 12,377,177 26.0 Secondary 3,981 25,031,220 52.5 High school 1,023 6,793,646 14.3 1,227 3,447,042 7.2 College, university Occupation – Correlates of SHS at home Manager/Professional 845,000 3,120,000 6.6 Office worker Service/Sales 220,000 1,589,000 916,000 8,991,000 2.0 19.2 Farming 3,069,000 23,255,000 49.6 Forestry/Fishing 120,000 867,000 1.8 Construction/Mining 317,000 2,442,000 5.2 Production/Driving 834,000 6,063,000 12.9 Other 248,000 1,272,000 2.7 Ethnicity Kinh (the majority) 8,555 54,368,513 84.5 Others 1,370 9,952,252 15.5 Single 1,882 16,846,557 26.2 Married 7,078 43,452,453 67.6 Marital status Separate 67 218,162 0.3 Divorce 152 556,605 0.9 740 3,214,116 5.0 Widow Logistic regression models were performed (presented as odds ratio (OR) and corresponding 95% CI) to examine the association between status of exposure to SHS among nonsmokers at home and selected socio-demographic factors Because education level was reported only among respondents 25? years old, two models were constructed: Model a: for all the study subjects (all aged 15 years and over) education was excluded; and Model b: for those aged 25 years and over and education was included as an independent variable The models showed that the significant correlates of the status of exposure to SHS at home were as listed in Table • • Area Urban – 4,958 19,724,648 30.7 Rural 4,967 44,596,117 69.3 9,925 64,320,765 Total occupation, Forestry/Fishing people (77.5%) and Farmers (73.5%) had the highest exposure to SHS at home, whereas Manager/Professional staff had the lowest (48.3%) There was no specific pattern of exposure to SHS at home and at work by economic status However, the prevalence of exposure to SHS at home among people in the higher quintile was significantly higher than that among those in the lower quintile (69.7% in quintile and 55.6% in quintile 5) By ethnicity, Kinh people had lower prevalence of exposure to SHS at home compared with other ethnic minority groups There was no statistically significant difference in the prevalence of exposure to SHS at work by marital status By residence, people living in rural areas (72.0%) were more likely to be exposed than those living in urban areas (57.7%) Table lists regulations on tobacco smoking at home in Vietnam Only 10.7% of the study respondents reported that smoking is never allowed in their home Most households had no indoor smoking rule (62.7%) • 100 (65.2% vs 68.8%, respectively) Exposure to SHS at home decreased with increasing age The highest exposure to SHS at home was among those age 15–24 (74.2%) and the lowest was among those 65 and above (57.2%) The prevalence of exposure to SHS at home among nonsmoking women aged 15–44 was 72.4% By education, adults with primary education or less (71.5%) had the highest prevalence of exposure to SHS at home and those with college degrees or above (57.2%) had the lowest By • • • Gender: Females were more likely than males to be exposed to SHS at home Age: The prevalence of exposure to SHS at home decreased with increasing age Occupation: People working as Service/Sales, Farmer, and Production/Driving employees were more likely than Manager/Professional staff to be exposed to SHS at home Ethnicity: People belong to ethnic minority groups were more likely than Kinh people to be exposed to SHS at home Residence: People living in rural areas were more likely than those living in urban areas to be exposed to SHS at home Smoking restriction in the home: Exposure to SHS at home was significantly prevalent in households where smoking is allowed 123 104 Cancer Causes Control (2012) 23:99–107 Table Pattern of SHS at home among non-smoking populations by socio-demographic characteristics—GATS Vietnam, 2010 (n = 7563) Characteristic Prevalence of SHS at home (%) Table continued Characteristic 95% CI of the prevalence Lower bound (%) Upper bound (%) Male 65.2 62.7 67.1 Female 68.8 67.3 70.3 15–24 74.2 71.5 76.9 25–34 68.3 65.5 71.0 35–44 68.2 65.5 71.0 45–54 64.8 61.7 67.9 95% CI of the prevalence Lower bound (%) Upper bound (%) 66.2 68.9 Smoking is allowed at work No Gender Prevalence of SHS at home (%) 67.6 Yes 67.0 58.2 75.7 Believed smoking causes stroke, heart attack, and lung cancer Age No 71.0 69.0 72.9 Yes 65.1 63.4 66.9 Believed SHS is dangerous No 73.6 70.0 77.3 Yes 66.8 65.4 68.2 55–64 57.5 53.2 61.8 [64 Education 57.2 53.4 61.1 Primary 71.5 68.9 74.1 Secondary 66.8 64.7 68.8 High school 56.6 52.4 60.9 College, university 43.7 40.0 47.4 Indoor smoking is allowed 7.7 10.8 9.8 Indoor smoking is not allowed but exceptions 19.9 15.1 16.5 Job Table Regulations on tobacco smoking at home in Vietnam, GATS 2010 (n = 7,563) Description Urban (%) Rural (%) Overall (%) Manager/ Professional 48.3 42.9 53.7 Indoor smoking is never allowed 16.5 8.2 10.7 Office worker 58.3 48.7 67.2 No indoor smoking rule 55.7 65.9 62.7 Service/Sales 68.9 65.7 71.9 Do not know, no response 0.3 0.2 0.2 Farming 73.5 71.0 75.9 Forestry/Fishing Construction/ Mining 77.5 66.2 62.7 55.4 87.5 75.5 Production/Driving 67.8 62.4 72.8 Others 63.0 53.5 71.6 Discussion Quintile 69.7 66.9 72.5 Quintile 74.0 71.2 76.7 Quintile 73.8 70.7 76.8 Quintile 65.1 62.2 68.1 Quintile 55.6 52.8 58.5 70.9 68.0 68.2 66.5 73.6 69.5 The findings from this study showed that very many nonsmokers in Vietnam were exposed to SHS Up to 67.6% of non-smokers (equivalent to approximately 33 million people) aged 15 and above were exposed to SHS at home The Vietnam National Health Survey 2001–2002 also reported that 63% of households in Vietnam had at least one smoker [14] The prevalence of exposure to SHS at home in Vietnam similar to that reported in the GATS conducted in China (67.3%) [17], but was higher than the corresponding figures found in the Philippines (44.8%) [18] and in Thailand (39.1%) [19] The high prevalence of exposure to SHS at home in Vietnam can be explained by the fact that tobacco control in the country has not yet prioritized a focus on smoke-free homes Furthermore, even though smoking is strictly prohibited in indoor workplaces and public places, for example schools, kindergartens, health facilities, libraries, cinemas, theatres, and community cultural centers, and on • Education: People with lower educational level were more likely to be exposed to SHS at home Asset quintile Marital status Single Married Separate 50.1 33.7 66.5 Divorce 48.2 36.6 59.8 Widow 51.5 46.8 56.3 Urban 57.7 55.9 59.5 Rural 72.0 70.3 73.7 Area Smoking is allowed at home No 65.3 63.9 67.0 Yes 88.5 85.6 91.4 123 Cancer Causes Control (2012) 23:99–107 105 Table Results from logistic regression analysis of the association between exposure to SHS at home with selected socio-demographic factors, among non-smokers—Vietnam GATS, 2010 Characteristic Model 1a (Education excluded, people aged 15?) OR (95% CI) Model 1b (Education included, people aged 25?) OR (95% CI) Gender Male 1.00 1.00 Female 1.2 [1.1–1.4]* 1.2 [1.1–1.4]* Age group Table continued Characteristic Model 1a (Education excluded, people aged 15?) OR (95% CI) Model 1b (Education included, people aged 25?) OR (95% CI) Believed SHS is dangerous No 1.00 1.00 Yes 0.8 [0.6–1.0] 0.9 [0.7–1.1] Education Primary – 1.00 Secondary – 0.7 [0.6–0.9]* Aged 15–24 1.00 – Aged 25–34 0.6 [0.5–0.8] 1.00 High school – 0.6 [0.4–0.8]* College, university – 0.4 [0.3–0.6]* Aged 35–44 0.6 [0.4–0.8]* 0.9 [0.7–1.0] Aged 45–54 0.5 [0.4–0.7]* 0.7 [0.6–0.9]* Aged 55–64 0.3 [0.2–0.5]* 0.5 [0.4–0.6]* Aged [64 0.4 [0.3–0.5]* 0.4 [0.3–0.6]* * p \ 0.05 Occupation Manager/Professional 1.00 1.00 Office worker 1.4 (0.9–2.2) 1.3 (0.8–2.0) Service/Sales 2.1 (1.6–2.7)* 1.7 (1.2–2.4)* Farming 2.0 (1.5–2.6)* 1.6 (1.1–2.3)* Forestry/Fishing 2.1 (1.0–4.4) 1.4 (0.6–3.1) Construction/Mining 1.8 (1.0–3.1) 1.6 (0.9–2.9) Production/Driving 1.8 (1.3–2.4)* 1.6 (1.1–2.4)* Others 1.4 (0.9–2.1) 1.1 (0.7–1.8) Asset quintile Quintile 1.00 1.00 Quintile 1.4 [1.1–1.7] 1.2 [1–1.6] Quintile 1.5 [1.2–1.8] 1.2 [1–1.6] Quintile 1.3 [1.0–1.6] [0.8–1.3] Quintile 1.1 [0.9–1.4] [0.8–1.3] Ethnicity Kinh (the majority) 1.00 1.00 Others 1.3 [1.1–1.7]* 1.4 [1.1–1.8]* Single 0.9 [0.7–1.2] 0.8 [0.6–1.1] Married 1.00 1.00 Separate 0.5 [0.3–0.9] 0.5 [0.2–0.9] Divorce 0.5 [0.3–0.8] 0.5 [0.3–0.7] Marital status Widow Area Urban 1.00 1.00 Rural 1.4 [1.3–1.7] 1.2 [1–1.4] Smoking is allowed at home No 1.00 1.00 Yes 3.9 [2.9–5.4]* 3.9 [2.8–5.6]* Smoking is allowed at work No 1.00 1.00 Yes 0.7 [0.5–1.1] 0.7 [0.4–1.2] Believed smoking causes stroke, heart attack, and lung cancer No 1.00 1.00 Yes 0.9 [0.8–1] 0.9 [0.8–1] public transport (according to the government’s Decision No 1,315/QÐ-TTg), the prevalence of exposure to SHS at work and in public places were still very high [20] Violation of the smoke-free workplace and public places regulation has been shown to have negative effect on smoking behaviour in private settings [21] Legislation should consider the issue of the smoke-free home in the near future to protect children and vulnerable household members from SHS in the home Community health education programmes to raise public awareness and practice are also needed to encourage families to make their homes smokefree, which would protect children and other family members from the dangers of second-hand smoke Scientific evidence has shown that voluntary smoke-free home policies reduce exposure of children and adult non-smokers to second-hand smoke, reduce smoking in adults, and seem to reduce smoking in youths [22] The GATS Vietnam 2010 revealed that females had higher prevalence of exposure to SHS at home than males and this finding implied that even though the prevalence of smoking among Vietnamese women was low, they have still been greatly exposed to the hazards of tobacco smoke This phenomenon could be explained by the fact that many non-smoking women in Vietnam live with a male smoker and they spend most of their time at home This finding is consistent with a study from China [23] Our study revealed that the prevalence of exposure to SHS at home among non-smoking women of reproductive age was high (72.4%) There is much published research, and studies are now confirming that inhaling second hand cigarette smoke also causes reproduction problems [1] Our study also found that other disadvantaged people in Vietnam, for example those belonging to ethnic minority groups, rural dwellers, and people with lower education were more likely to be exposed to SHS at home This 123 106 indicates there is an inequity problem in exposure to SHS at home in Vietnam This finding is similar to those from studies from China [23, 24], USA [25], and Spain [26], and implies that tobacco control policies should pay special consideration to these disadvantaged populations Our study demonstrated the effect of smoking restriction in reducing the prevalence of exposure to SHS at home Similar findings were also obtained in studies in China [23, 24] Because many households in Vietnam still have no regulations restricting smoking at home, a smoke-free household policy is necessary to reduce household SHS exposure In fact, the GATS Vietnam showed that most adults supported smoke-free home regulations [27] Promotion of smoke-free homes may be an important area to emphasize in a tobacco control campaign Our study has several limitations First, data from the GATS on exposure to SHS are self-reported and no objective measurement of levels of exposure to SHS was conducted Second, estimates of SHS exposure discussed here did not consider duration of exposure Third, the cross-sectional design of the study does not enable us to establish any causal connection In summary, the GATS Vietnam 2010 has shown that a high percentage of people are exposed to second-hand smoke at home The significant correlates of the status of exposure to SHS at home were female gender, ethnic minority, low education, and lack of smoking restriction at home Because smoke-free homes have not been included in tobacco-control policies, advocating of smoke-free homes initiatives is urgently needed Special considerations should be given to disadvantaged people, because they are more likely than the better-off to be exposed to SHS at home, and to promoting community health-education programs to raise public awareness of the harm of tobacco use and exposure to tobacco smoke Further studies are also needed to overcome the limitations of this study, for example a study with objective measurement of level of exposure to SHS (blood or urine cotinine) and study of SHS exposure among children, women, the poor, etc Cancer Causes Control (2012) 23:99–107 10 11 12 13 14 15 16 17 Acknowledgments This study was funded by the Bloomberg Philanthropies We highly appreciate the contributions to the success of the survey made by the Centers for Disease Control and Prevention in Atlanta, the CDC Foundation, the World Health Organization, the General Statistics Office of Vietnam, and Hanoi Medical University 18 19 20 References US Department of Health and Human Services (2006) The health consequences of involuntary exposure to tobacco smoke 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