Background
Secondhand smoke (SHS) exposure is causally linked to cardiovascular disease, respiratory effects, and lung cancer [
1‐
4]. Exposure to SHS in children is associated with increased risks of asthma, middle ear infections, and sudden death syndrome in infancy [
4]. SHS exposure caused 603,000 premature deaths in 2004, equivalent to 1.0% of worldwide mortality, based on data from 192 countries [
5]. The US Surgeon General concluded that there is no risk-free level of SHS exposure and only the elimination of indoor smoking can protect non-smokers [
4].
The extensive evidence of adverse health effects associated with SHS exposure has led many countries to introduce smoke-free regulations in indoor public spaces and work places. The implementation of smoke-free regulations has resulted in an improvement in indoor air quality [
6,
7] and the health of non-smoking staff in hospitality venues [
8,
9]. However, there has been a limited implementation of similar regulations in personal living spaces. Although it might be difficult to pass legislation to restrict smoking in a private home, public housing could be smoke-free. Smoke-free public rule of the U.S. Department of Housing and Urban Development went into effects since February 3, 2017 [
10]. Public Housing Authorities were required to adopt and implement a smoke-free regulation in all of their public housing properties by August 2018.
Residents living in multi-unit housing (MUH) are particularly susceptible to SHS exposure because SHS can be transferred between units in MUH [
11]. In 2009, 44.0–46.2% of Americans who lived in smoke-free MUH reported SHS incursion into their units [
12]. In Denmark, 28.2% of MUH residents living in non-smoking homes reported that SHS from their neighbors had seeped into their homes [
13]. In Hong Kong, 11.8% of students who lived in homes without smokers were experienced SHS in their homes that came from neighboring flats [
14]. Because people spend the majority of their time in their homes, SHS exposure at home can be a significant contributor to their total SHS exposure [
4].
The prevalence of SHS incursion in MUH in Korea has not been established. Furthermore, most of the studies that have been conducted have examined the relationship between SHS incursion into MUH living spaces and socio-demographic factors. Smoking status, the presence of children living in the home, and the type of MUH have been identified as predictors of SHS incursion [
13,
15,
16]. A previous study reported that up to 65% of the air in a private unit could come from somewhere else in the building depending on the construction and age of building [
17]. The aim of this study was to determine the prevalence of SHS incursion in MUH and to establish the relationship between SHS incursion into the homes of non-smoking residents and socio-demographic and built environmental factors.
Results
The distributions of sex, age, and residential region in the Seoul population obtained from the MI [
18] and the population in this study are shown in Table
1. The distributions of sex and residential region in the study population were similar to those of the Seoul population. The study population was slightly younger, on average, than the Seoul population.
Table 1
Distributions of sex, age, and residential region in Seoul and study population
Sex |
Men | 49.6 | 49.8 |
Women | 50.4 | 50.2 |
Age (years) |
19–29 | 20.7 | 22.7 |
30–39 | 24.0 | 26.0 |
40–49 | 24.5 | 26.6 |
≥ 50 | 30.8 | 24.7 |
Region |
Urban areas | 5.1 | 5.0 |
Northeast | 31.2 | 31.4 |
Northwest | 11.8 | 11.7 |
Southeast | 30.5 | 30.4 |
Southwest | 21.4 | 21.6 |
The relationship of socio-demographic factors with the frequency of SHS incursion for smoking and non-smoking residents is shown in Table
2. A total of 74.8% of the residents were non-smokers. Women were more likely than men to be non-smokers (62.1%,
p < 0.001). Non-smokers were older (
p < 0.001) and had lower household incomes (
p = 0.035) compared with smokers. Non-smokers were more likely than smokers to live in an apartment (51.2%,
p < 0.001) and to spend more time at home (
p < 0.001), and were less likely to live with children (38.6%,
p = 0.018). Non-smokers were likely to have been residents for a longer period (
p = 0.019). Non-smokers were more likely than smokers to support the implementation of smoke-free regulations in MUH (89.9%,
p < 0.001), and to live in homes with a personal smoke-free rule (72.1%,
p < 0.001). Non-smokers were more likely than smokers to have reported an SHS incursion within the previous 12 months (
p < 0.001). However, level of educational attainment, number of residents, type of ownership, and presence of other smokers inside a home did not differ between smoking and non-smoking residents.
Table 2
Characteristics between smoking and non-smoking resident in MUH
Overall | 100.0 | 25.2 | 74.8 | |
Sex |
Men | 49.8 | 85.2 | 37.9 | <0.001 |
Women | 50.2 | 14.8 | 62.1 |
Age (years) |
19–29 | 22.7 | 19.6 | 23.7 | <0.001 |
30–39 | 26.0 | 28.6 | 25.2 |
40–49 | 26.6 | 31.2 | 25.1 |
≥ 50 | 24.7 | 20.6 | 26.0 |
Household income (USD/month) |
< 2000 | 7.2 | 5.7 | 7.8 | 0.035 |
2000–3999 | 29.2 | 28.1 | 29.5 |
4000–5999 | 37.0 | 35.9 | 37.4 |
6000–7999 | 15.6 | 16.5 | 15.3 |
≥ 8000 | 11.0 | 13.8 | 10.0 |
Education |
Less than university level | 34.9 | 33.2 | 35.5 | 0.418 |
University level | 56.2 | 58.4 | 55.4 |
More than university level | 8.9 | 8.4 | 9.0 |
Housing type |
Apartment | 50.1 | 46.8 | 51.2 | <0.001 |
Attached home | 49.9 | 53.2 | 48.8 |
Time spent at home (hours/day) |
< 5 | 27.5 | 35.6 | 24.8 | <0.001 |
5–9 | 51.8 | 51.7 | 51.8 |
≥ 10 | 20.7 | 12.7 | 23.4 |
Number of residents (people) |
< 4 | 49.2 | 52.4 | 48.2 | 0.057 |
≥ 4 | 50.8 | 47.6 | 51.8 |
Children living in home (aged ≤18 years) |
No | 60.0 | 56.1 | 61.4 | 0.018 |
Yes | 40.0 | 43.9 | 38.6 |
Type of ownership |
Owned | 56.7 | 54.1 | 57.6 | 0.179 |
Leased based on deposit | 29.7 | 30.4 | 29.4 |
Monthly rent | 13.6 | 15.4 | 12.9 |
Duration of residence (years) |
< 2 | 26.9 | 25.4 | 27.4 | 0.019 |
2–3 | 19.8 | 23.5 | 18.5 |
≥ 4 | 53.3 | 51.1 | 54.1 |
Presence of other smokers inside the homea
|
No | 62.9 | 60.2 | 63.8 | 0.819 |
Yes | 37.1 | 39.8 | 36.2 |
Support for the implementation of smoke-free regulations in MUH |
No | 16.8 | 37.0 | 10.1 | <0.001 |
Yes | 83.2 | 63.0 | 89.9 |
Living in a home with a personal smoke-free rule |
No | 37.5 | 66.2 | 27.9 | <0.001 |
Yes | 62.5 | 33.8 | 72.1 |
Frequency of SHS incursion |
Never | 28.6 | 37.2 | 25.7 | <0.001 |
≤ 1 times/month | 19.4 | 16.5 | 20.3 |
2–4 times/month | 25.3 | 25.2 | 25.3 |
> 4 times/month | 26.8 | 21.1 | 28.7 |
The proportions of general smoking locations in smokers’ homes were estimated using data from residents who were either smokers or resided with smokers (n = 1359). Among the residents who smoked at their homes (n = 560), the most common smoking location was the balcony (51.4%, n = 288), followed by the bathroom (20.2%, n = 113), main room (14.8%, n = 83), and outside the front door (13.6%, n = 76).
Although there was no difference in SHS incursion between the non-smoking residents who lived in homes with and without a personal smoke-free rule (p = 0.568), only non-smoking residents who lived in homes with a personal smoke-free rule were used for further analysis (n = 1784). In total, 74.7% of these non-smoking residents (n = 1333) reported that they had experienced SHS incursion into their home within the previous 12 months. In total, 9.9% of the residents (n = 176) reported that they had experienced SHS incursion every day, and 44.2% (n = 788) reported that they had experienced SHS incursion once a week or more. The residents who had experienced SHS incursion reported the entry point of SHS into their homes (n = 1333); the main source of SHS incursion was the balcony (45.7%, n = 609), followed by windows (28.4%, n = 378), bathroom (12.9%, n = 172), front door (11.7%, n = 156), and other locations (1.4%, n = 18).
Table
3 shows characteristics of the non-smoking residents living in home with a personal smoke-free rule by frequency of SHS incursion. Residents who were women (
p = 0.020), spent more time at home (
p < 0.001), lived with children (
p < 0.001), and supported the implementation of smoke-free homes in MUH (
p = 0.020) exhibited a positive trend across the categories of SHS incursion. Residents who lived in large homes exhibited a negative trend across the categories (
p = 0.038). Method of natural ventilation at residents’ homes was related to frequency of SHS incursion (
p = 0.042). Residents who lived in homes with more frequent natural ventilation exhibited a positive trend across the categories (
p < 0.001). However, age, household income, level of educational attainment, housing type, number of residents, type of ownership, duration of residential period, presence of other smokers inside the home, date of construction, type of corridor, presence of a balcony, and air-conditioning were not significantly associated with frequency of SHS incursion.
Table 3
Characteristics of the non-smoking residents living in home with smoke-free rules by SHS incursion
Socio-demographic factor |
Sex |
Men | 38.5 | 39.9 | 42.6 | 39.8 | 33.2 | 0.020 |
Women | 61.5 | 60.1 | 57.4 | 60.2 | 66.8 |
Age (years) |
19–29 | 22.6 | 24.4 | 20.2 | 23.7 | 21.9 | 0.079 |
30–39 | 26.0 | 23.1 | 23.5 | 29.2 | 27.6 |
40–49 | 24.8 | 20.4 | 28.1 | 23.9 | 27.0 |
≥ 50 | 26.6 | 32.2 | 28.1 | 23.2 | 23.5 |
Household income (USD/month) |
< 2000 | 7.8 | 10.4 | 6.0 | 5.1 | 9.3 | 0.171 |
2000–3999 | 29.6 | 30.6 | 29.2 | 29.9 | 28.7 |
4000–5999 | 36.7 | 37.5 | 36.3 | 37.8 | 35.3 |
6000–7999 | 15.2 | 11.1 | 18.6 | 16.8 | 15.1 |
≥ 8000 | 10.6 | 10.4 | 9.8 | 10.4 | 11.5 |
Education |
Less than university level | 34.8 | 37.3 | 30.1 | 33.6 | 36.9 | 0.698 |
University level | 55.5 | 54.5 | 57.9 | 54.6 | 55.5 |
More than university level | 9.7 | 8.2 | 12.0 | 11.7 | 7.6 |
Housing type |
Apartment | 51.6 | 50.1 | 57.9 | 53.8 | 46.6 | 0.147 |
Attached house | 48.4 | 49.9 | 42.1 | 46.2 | 53.4 |
Time spent at home (hours/day) |
< 5 | 25.3 | 29.5 | 27.3 | 25.7 | 20.0 | <0.001 |
5–9 | 51.7 | 52.3 | 50.0 | 52.2 | 52.0 |
≥ 10 | 22.9 | 18.2 | 22.7 | 22.1 | 28.0 |
Number of residents (people) |
< 4 | 49.0 | 51.9 | 49.7 | 46.2 | 48.5 | 0.207 |
≥ 4 | 51.0 | 48.1 | 50.3 | 53.8 | 51.5 |
Children living in home (aged ≤18 years) |
No | 61.0 | 70.1 | 59.0 | 58.4 | 56.9 | <0.001 |
Yes | 39.0 | 29.9 | 41.0 | 41.6 | 43.1 |
Type of ownership |
Owned | 57.4 | 56.5 | 59.0 | 59.3 | 55.3 | 0.830 |
Leased based on deposit | 29.9 | 27.9 | 30.1 | 29.9 | 31.5 |
Monthly rent | 12.7 | 15.5 | 10.9 | 10.8 | 13.2 |
Duration of residence (years) |
< 2 | 27.8 | 30.4 | 24.6 | 24.1 | 31.1 | 0.495 |
2–3 | 18.7 | 17.7 | 16.9 | 20.6 | 19.2 |
≥ 4 | 53.5 | 51.9 | 58.5 | 55.3 | 49.7 |
Presence of other smokers inside homeb
|
No | 69.6 | 72.9 | 71.0 | 64.8 | 69.7 | 0.116 |
Yes | 30.4 | 27.1 | 29.0 | 35.2 | 30.3 |
Support for the implementation of smoke-free regulations in MUH |
No | 9.0 | 12.4 | 6.8 | 9.3 | 7.2 | 0.020 |
Yes | 91.0 | 87.6 | 93.2 | 90.7 | 92.8 |
Built environmental factor |
Date of construction (year) |
Before 1995 | 27.3 | 27.3 | 26.8 | 24.8 | 29.9 | 0.322 |
1995–1999 | 23.5 | 23.7 | 22.4 | 24.8 | 22.9 |
2000–2004 | 22.0 | 21.5 | 22.4 | 23.2 | 21.2 |
2005–2009 | 14.7 | 12.6 | 18.0 | 13.5 | 15.1 |
2010 or later | 12.5 | 14.9 | 10.4 | 13.7 | 10.9 |
Type of corridor |
Stairwell | 77.1 | 78.7 | 78.4 | 75.0 | 76.7 | 0.142 |
Indoor corridor | 14.0 | 14.2 | 13.4 | 15.0 | 13.4 |
Outdoor corridor | 8.9 | 7.1 | 8.2 | 10.0 | 9.9 |
Home size (m2) |
< 66 | 25.2 | 26.8 | 22.7 | 22.1 | 28.3 | 0.038 |
66–98 | 35.8 | 32.6 | 32.5 | 38.1 | 39.0 |
≥ 99 | 39.0 | 40.6 | 44.8 | 39.8 | 32.6 |
Presence of balcony |
No | 22.1 | 23.3 | 25.4 | 19.9 | 20.6 | 0.128 |
Yes | 77.9 | 76.7 | 74.6 | 80.1 | 79.4 |
Presence of air–conditioning |
No | 18.3 | 19.5 | 16.9 | 14.6 | 21.6 | 0.558 |
Yes | 81.7 | 80.5 | 83.1 | 85.4 | 78.4 |
Method of natural ventilation |
Opening windows | 52.7 | 55.4 | 58.5 | 50.0 | 48.7 | 0.042 |
Opening front doors | 5.3 | 4.2 | 4.4 | 6.4 | 6.0 |
Opening windows and front doors | 18.3 | 16.2 | 14.8 | 22.1 | 19.2 |
Windows always slightly open | 23.7 | 24.2 | 22.4 | 21.5 | 26.0 |
Frequency of natural ventilation (times/week) |
< 5 | 31.9 | 34.4 | 38.5 | 32.7 | 24.3 | <0.001 |
≥ 5 | 68.1 | 65.6 | 61.5 | 67.3 | 75.7 |
The univariate and multivariate ordinal logistic regression model of SHS incursion are shown in Table
4. In the univariate analysis, the proportional odds assumption was violated for home size (
p = 0.049) and frequency of natural ventilation (
p = 0.019); thus, different effects in these variables were estimated for the different levels of frequency of SHS incursion. In the multivariate analysis, all variables except sex seemed consistent effects with univariate analysis on SHS incursion. Residents who spent 5–9 h/day and those who spent ≥10 h/day at home were more likely to report SHS incursion than were those who spent <5 h/day at home. Residents who lived with children and those who supported the implementation of smoke-free regulations in MUH were more likely to report SHS incursion than were those who did not. Residents who lived in home sized ≥99 m
2 were less likely to report SHS incursion in the 2 highest SHS incursion categories and in the highest SHS incursion categories than were those who lived in home sized <66 m
2. Residents who lived in homes with natural ventilation provided by open front doors or both open windows and front doors were more likely to report SHS incursion than were those with only open windows. Residents who lived in homes with a natural ventilation frequency of ≥5 times/week were more likely to report SHS incursion in the 3 and 2 highest SHS incursion categories and in the highest SHS incursion categories than were those who lived in homes with ventilation frequency of <5 times/week.
Table 4
Factors associated with SHS incursion among non-smoking residents living in home with smoke-free rulesa
Socio-demographic factor |
Sex |
Men | 1.00 | | 1.00 | |
Women | 1.23 (1.04–1.46) |
0.018
| 1.11 (0.93–1.33) | 0.242 |
Time spent at home (hours/day) |
< 5 | 1.00 | | 1.00 | |
5–9 | 1.29 (1.05–1.58) |
0.014
| 1.28 (1.05–1.57) |
0.017
|
≥ 10 | 1.68 (1.32–2.14) |
<0.001
| 1.60 (1.25–2.06) |
<0.001
|
Children living in home (aged ≤18 years) |
No | 1.00 | | 1.00 | |
Yes | 1.41 (1.19–1.67) |
<0.001
| 1.40 (1.17–1.66) |
<0.001
|
Support for the implementation of smoke-free regulations in MUH |
No | 1.00 | | 1.00 | |
Yes | 1.43 (1.07–1.91) |
0.017
| 1.47 (1.09–1.99) |
0.011
|
Built environmental factor |
Home size (m2) |
< 66 | 1.00 | | 1.00 | |
66–98 | | | | |
OR 1d
| 1.23 (0.93–1.63) | 0.730 | 1.15 (0.87–1.53) | 0.327 |
OR 2e
| 1.16 (0.91–1.48) | 0.224 | 1.05 (0.82–1.35) | 0.690 |
OR 3f
| 0.96 (0.74–1.24) | 0.143 | 0.87 (0.67–1.13) | 0.290 |
≥ 99 | | | | |
OR 1d
| 1.03 (0.79–1.35) | 0.835 | 0.95 (0.72–1.25) | 0.695 |
OR 2e
| 0.83 (0.66–1.06) | 0.129 | 0.73 (0.57–0.94) |
0.013
|
OR 3f
| 0.66 (0.51–0.86) |
0.002
| 0.59 (0.45–0.77) |
<0.001
|
Method of natural ventilation |
Opening windows | 1.00 | | 1.00 | |
Opening front doors | 1.46 (1.00–2.14) | 0.051 | 1.59 (1.08–2.33) |
0.018
|
Opening windows and front doors | 1.32 (1.05–1.65) |
0.017
| 1.27 (1.01–1.60) |
0.038
|
Windows always slightly open | 1.17 (0.96–1.44) | 0.128 | 1.17 (0.95–1.45) | 0.137 |
Frequency of natural ventilation (times/week) |
< 5 | 1.00 | | 1.00 | |
≥ 5 | | | | |
OR 1d
| 1.16 (0.93–1.46) | 0.193 | 1.11 (0.88–1.40) |
<0.001
|
OR 2e
| 1.44 (1.18–1.76) |
<0.001
| 1.41 (1.15–1.74) |
0.001
|
OR 3f
| 1.68 (1.33–2.12) |
<0.001
| 1.64 (1.29–2.08) |
<0.001
|
We further conducted an ordinal logistic regression analysis among smoking residents living in home with a smoke-free rule (n = 433). The final multivariate ordinal logistic regression model was fit for the proportional odds assumption (p = 0.179). In the multivariate analysis, residents who lived with children (OR = 1.53, 95% CI = 1.07–2.17) and those who supported the implementation of smoke-free regulations in MUH (OR = 2.07, 95% CI = 1.34–3.18) were more likely to report SHS incursion than were those who did not. Residents who lived in homes with indoor corridor (OR = 1.65, 95% CI = 1.04–2.63) and those who lived in homes with natural ventilation provided by both windows and front doors (OR = 2.65, 95% CI = 1.70–4.12) or those with always slightly open windows (OR = 2.13, 95% CI = 1.34–3.39) were more likely to report SHS incursion than a reference value. Other variables were not significantly associated with SHS incursion.
Discussion
The smoking rate of MUH residents in the study population was 25.2%, which was higher than that in the Seoul general population in 2014. Based on statistical data from the Community Health Survey (CHS), a comprehensive health status survey program in Korea, the smoking rate in the Seoul population (≥19 years) in 2014 was 20.6% [
22]. The results of the CHS indicate that the smoking rate increases with age from 19 to 49 years (20.3–25.8%), but then decreases sharply from 50 to 70 years or older (9.0–13.9%). One possible reason for the higher smoking rate in this study could be the low proportion of respondents older than 60 years, which might have led to an overestimation of the smoking rate.
The self-reported frequency of SHS incursion differed between smoking and non-smoking residents. In the present study, smokers were less likely to report SHS incursion. This might be explained by a difference in the perception of SHS exposure between smokers and non-smokers. Smokers could be habituated and less likely to be irritated by to the smell of SHS [
16]. Similar findings have been reported that residents who were smokers were less likely to report SHS incursion in MUH than were non-smokers [
13,
15,
16].
Among the non-smokers who lived in homes with a personal smoke-free rule, 74.7% had experienced SHS incursion within the previous 12 months. One in 10 residents reported that they experienced daily SHS incursion. The prevalence of SHS incursion in this study was higher than that reported in previous studies. In a 2010 study in the US, 44% of residents in MUH with a personal smoke-free home rule had experienced SHS incursion in their units within the previous 12 months [
23]. In that study, the smoking rate of the residents was 21.1%. In a 2009 study in New York State, 46.2% of residents with a personal smoke-free home policy had experienced SHS incursion in their unit within the previous 12 months [
15]. The smoking rate of the study population was 19.0%. A possible reason for the high prevalence of SHS incursion in the present study might be because smoking rate in this study was higher than that in previous studies conducted in the USA.
The majority of non-smoking residents who had experienced SHS incursion within the past 12 month reported that SHS entered their homes through the balcony or windows. The ingress route taken by SHS incursion was slightly higher in bathrooms than through the front door. SHS could migrate through the balcony [
15], hallway (similar to a corridor) [
11], and bathroom ceiling exhaust fans [
24]. In this study, it was suggested that SHS incursion into bathrooms might have been associated with migration of SHS through bathroom ceiling exhaust fans in other units. A front door was associated with migration of SHS from the corridor outside a home.
In this study, the source of SHS incursion was consistent with the smoking locations used by smokers in their homes in MUH. The most common smoking location was the balcony, followed by the bathroom, main room, and outside the front door. This suggested that smoking in these locations might be associated with SHS incursion into other units. Therefore, limitations on smoking in these locations should be placed to reduce the SHS incursion into other units in MUH. Because it might be difficult to implement smoke-free regulations in MUH, offering educational information on how to implement smoke-free policy to building managers or owners could be the first step for smoke-free MUH [
25].
In the multivariate analysis, residents who spent more time at home were more likely to report SHS incursion. As the time spent at home increased, the ORs of SHS incursion also tended to increase. As residents spend more time in their home, they are more likely to be exposed to SHS incursion. Thus, MUH residents who spend long periods at home might be at risk of high SHS exposure from such incursion.
Residents who lived with children and who supported the implementation of smoke-free regulations in MUH were more likely to report SHS incursion. MUH residents who lived with children might be more sensitive to SHS incursion because their children are being exposed to SHS [
13]. MUH residents who experienced a high level of SHS incursion might express more support for smoke-free regulations in MUH so as to reduce their SHS exposure at home.
Among the built environmental factors investigated here, home size was significantly associated with SHS incursion. Overall, residents who lived in homes ≥99 m
2 in size were less likely to report SHS incursion than were those in homes of <66 m
2. This might be because home size was associated with housing type. In Korea, the average home size per person was larger in an apartment than in an attached home in 2010 [
26]. In the present study, residents who lived in an apartment were slightly less likely to report SHS incursion than were those in an attached home. Therefore, residents who lived in larger homes were more likely to live in an apartment and might therefore be less likely to experience SHS incursion.
Factors related to natural ventilation were associated with SHS incursion. Residents who lived in homes with natural venation provided by opening the front door or by opening both the front door and windows were more likely to report SHS incursion than were those with natural venation provided only by opening the windows. The ORs for providing natural ventilation with an open front door were higher than those where natural ventilation was provided by opening both windows and front doors. Furthermore, residents who frequently used natural ventilation were more likely to report SHS incursion. The results of the study indicate that residents who lived in homes where natural ventilation was provided by opening the front door and those who lived in homes with frequent natural ventilation were more likely to be exposed to SHS incursion.
In this study, SHS incursion, a dependent variable, was assigned as an ordinal variable in a logistic regression analysis. Previous studies have used dichotomized dependent variables for SHS incursion to examine associated factors [
15,
23]. When we used SHS incursion as a dichotomized dependent variable (i.e., no = 0 vs. yes = 1), the factors associated with SHS incursion among non-smoking residents living in home with a smoke-free rule in the multivariate logistic regression analysis were household income, children living in the home, time spent at home, and support for the implementation of smoke-free regulations in MUH. Other variables were not significantly associated with SHS incursion. This indicated that using SHS incursion as an ordinal variable might be a more useful approach to examine predictors for SHS incursion in MUH.
To our knowledge, this is the first study to determine prevalence and predictors of SHS incursion among MUH residents in Korea. The present study included socio-demographic factors as well as built environmental factors to determine predictors on SHS incursion. The findings of the present study could be useful for targeted effort to promote smoke-free regulation in MUH and understanding SHS exposure of residents in homes due to SHS incursion.
This study has a few limitations. We used self-reported SHS incursion experienced by residents within the previous 12 months. The self-report measure might be subject to variations and recall-bias due to a respondent’s sensitivity. Because SHS incursion was less likely to be reported by residents who were smokers, we used data from non-smoking residents to identify the factors associated with SHS incursion, which enabled better estimations. Another limitation was that SHS incursion was based on the detection of SHS by smell by MUH residents. Because we measured SHS incursion using a self-reported questionnaire, we could not confirm or quantify each resident’s exposure to SHS due to SHS incursion. Furthermore, self-report of SHS might partially be due to third-hand smoke particularly for the home with smokers in the past. Further study is needed using more specific SHS markers to provide a better understanding of SHS incursion in MUH.