Secondhand Smoke in Living Environments of Korea: Exposure, Health Risks, and Impacts of Smoke-free Regulation

Abstract

Secondhand smoke (SHS) exposure is causally linked to many adverse health effects in adults and children. There is no risk-free level of SHS exposure. To reduce SHS exposure, many countries have implemented smoke-free regulations in indoor public places. In hospitality venues such as restaurants and bars, the Korean government has granted gradual implementation of smoke-free regulations based on the size of the establishment. These regulations were implemented for restaurants and bars ≥150 m2 starting July 1, 2013. However, the effects of reduction of SHS exposure due to the implementation of the smoke-free regulations have not been established. Scientific evidence of the impact of smoke-free regulations is essential to support expansion of smoke-free policies to other indoor public places. <br/> Although smoke-free regulations have been implemented in indoor public places, such regulations might not be applicable to residences. Home environments are sources of SHS exposure. Even in smoke-free homes, residents could be exposed to SHS because of tobacco smoke migrating between neighboring units in multi-unit housing (MUH) via a process known as SHS incursion. Although the risks of SHS exposure in smoke-free MUH homes have received increased attention, little information on residents exposure and health effects due to SHS incursion were available. The main objectives of this study were to determine the effects of smoke-free regulations in indoor public places and to establish scientific evidence regarding the risks of exposure and the health effects due to SHS incursion into smoke-free homes.<br/> In the first study, the effects of smoke-free regulations in restaurants and bars were examined in terms of air quality, biomarker levels, and health effects on staff. This study measured indoor fine particles (PM2.5) in 146 hospitality venues, and urinary cotinine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) levels in 101 non-smoking staff members in 77 hospitality venues, before and 1 month after the regulations were implemented. Self-reported respiratory and sensory symptoms (i.e., eye/nose/throat irritation) were measured during both phases. In total, 121 venues and 95 non-smoking staff members in 71 venues were included in the final analysis. The geometric mean (GM) of indoor PM2.5 concentrations was significantly reduced in bars ≥150 m2, from 93.2 μg/m3 (geometric standard deviation, GSD = 2.2) before regulation to 55.3 μg/m3 (GSD = 2.2) after regulation (p<0.05). Although the urinary cotinine concentrations of staff in all venues did not change following regulation, the GM of total NNAL concentrations of staff in bars ≥150 m2 was significantly reduced, from 12.1 pg/mg creatinine (Cr) (GSD = 2.0) before regulation to 7.3 pg/mg Cr (GSD = 1.7) after regulation (p<0.05). The levels of PM2.5 and biomarker did not change in staff in restaurants ≥150 m2 due to the few smokers prior to regulation. The health effects on staff show that only sensory symptoms improved significantly in venues ≥150 m2, decreasing from 52% before regulation to 40% after regulation (p<0.05). These findings indicate that the implementation of smoke-free regulations significantly reduced the levels of PM2.5 and total NNAL concentrations of staff in bars ≥150 m2 and improved the sensory health of staff in venues ≥150 m2. However, no improvement was observed in the measured data or the health effects in venues <150 m2 where indoor smoke-free regulations were not applied.<br/> The purpose of the second study was to determine the prevalence of SHS incursion, and to establish the relationship between SHS incursion and socio-demographic and built environmental factors in MUHs. Population-based samples representing 2,600 adult residents living in MUH in Seoul, Korea were obtained through a web-based selection panel. Residents completed a questionnaire detailing socio-demographic factors, smoking status, frequency of SHS incursion, and built environmental factors. The presence of a personal smoke-free home rule was determined by residents declaring that no one smoked inside the home. Of the 2,600 participants, non-smoking residents who lived in homes with a personal smoke-free rule were selected for further analysis (n = 1,784). SHS incursion had been experienced by 74.7% of the residents within the previous 12 months. A multivariate ordinal logistic regression analysis indicated that residents who spent more time at home, lived with children, supported the implementation of smoke-free regulations in MUH, lived in small homes, lived in homes with natural ventilation provided by opening a front door or both the windows and a front door, and lived in homes with more frequent natural ventilation were more likely to have SHS incursion into their homes. Most non-smoking residents living in smoke-free homes in MUHs experienced SHS incursion into their homes.<br/> The purpose of the third study was to determine the relationship between SHS incursion and allergic symptoms in children living in homes without smokers in MUHs. We conducted a cross-sectional study in 2015 in Seoul, Korea. Children were recruited from elementary schools, kindergartens, and daycare centers. In total, 16,676 children between 1 and 13 years of age living without smokers in MUH were included in the analysis. Allergic symptoms during the previous 12 months (current wheeze, rhinitis, and eczema) and home environmental factors, including the frequency of SHS incursion during the previous 12 months, were examined using a questionnaire filled out by the parents or guardians of the children. The prevalence of current allergic symptoms in children was 4.9% for wheeze, 42.0% for rhinitis, and 28.1% for eczema. The prevalence of SHS incursion into childrens homes was 61.6%. In a multivariate logistic regression analysis adjusted for demographic and home environmental factors, children living in homes with SHS incursion (either no more than once a month or more than once a month) were more likely to have current wheeze, rhinitis, and eczema than those with no SHS incursion. Thus, SHS incursion into homes was associated with current wheeze, rhinitis, and eczema symptoms in children living in homes without smokers in MUH.<br/> The objective of the final study was to determine urinary cotinine concentrations in non-smoking residents of smoke-free homes and to establish the association of urinary cotinine with housing type and socio-demographic and SHS exposure factors. Data from the Korean National Environmental Health Survey (KoNEHS) I (2009–2011) were used. We examined 814 non-smoking adult residents who were not residing with smokers in apartments and in attached and detached housing and spent their time mainly indoors at home. In Korea, detached housing includes single-family and multifamily (e.g., single room studio) houses. Urinary cotinine was detected in 88% of the 814 non-smoking residents. The urinary cotinine concentrations of residents living in attached [GM: 1.25 ng/ml