Original Research
Assessment of Secondhand Smoke Exposure at School Among U.S. Middle and High School Students
The Journal of School Nursing 2015, Vol. 31(3) 212-218 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1059840514537075 jsn.sagepub.com
Olubode Ademola Olufajo, MD, MPH1,2, and Israel Terungwa Agaku, DMD, MPH3
Abstract To obtain nationally representative estimates of the prevalence of secondhand smoke (SHS) exposure at U.S. schools, we assessed the prevalence and correlates of SHS exposure at school among U.S. middle and high school students using data from the 2011 National Youth Tobacco Survey comprising of 18,866 students spread across all the U.S. states. Overall prevalence of SHS exposure at school was 25.7% (95% CI: [23.6%, 27.8%]). Multivariate logistic regression indicated that having ≥ 1 smoker friends (adjusted Odds Ratio [aOR] ¼ 2.92; p < .001); being a smoker (aOR ¼ 2.75; p < .001); and being aged 13–16 years, or ≥ 17 years (vs. 9–12 years) significantly increased the likelihood of SHS exposure. Understanding the health risks of SHS exposure alone did not seem to play a significant role in reducing exposure (aOR ¼ .89; p ¼ .342). These findings show there are significant levels of SHS exposure among students at U.S. middle and high schools, and sustained multipronged efforts are needed to reduce youth SHS exposure. Keywords National Youth Tobacco Survey, school, school nurses, secondhand smoke, students, tobacco control, youth
Secondhand smoke (SHS) exposure is responsible for over half a million deaths globally every year (Liu et al., 2013). SHS contains over 7,000 chemicals, including toxins and carcinogens that cause a wide range of diseases among nonsmokers, and no safe levels of exposure to SHS exist (U.S. Department of Health and Human Services [USDHHS], 2006). Health effects associated with SHS exposure include middle ear infections, nasal irritation, lower respiratory illnesses, decreased lung function, exacerbation of asthma, coronary heart disease, and various cancers (Song, Glantz, & Halpern-Felsher, 2009; USDHHS, 2006). SHS exposure is also known to be associated with increasing hospital visits, school absenteeism, rising medical ¨ berg, Woodcosts, and generally poorer health prospects (O ward, Peruga, & Pru¨ss-Ustu¨n, 2011; Saywell Jr, Zollinger, Lewis, Jay, & Spitznagle, 2013; USDHHS, 2006). Despite the proliferation of comprehensive state and local laws prohibiting smoking in public areas (Hopkins et al., 2012), the proportion of nonsmokers exposed to SHS remains high. Children and youth aged 0–15 years account for a large proportion of nonsmokers exposed to SHS in the ¨ berg et al., 2011), mostly from private United States (O environments such as the home and the family car (Cartmell et al., 2011). During 2003–2006, approximately 17.8% of U.S. youths aged 3–19 years were exposed to SHS in the home, while 29.8% of U.S. middle and high school students
reported exposure to SHS in a car during 2009 (King, Dube, & Tynan, 2012; Marano, Schober, Brody, & Zhang, 2009). The school environment is another potential area where youths may be exposed to SHS. The fact that youth are a high-risk group for the initiation and experimentation with tobacco products further increases the risk for SHS exposure in this age-group particularly in environments where youths congregate, such as at school (Leatherdale, McDonald, Cameron, Jolin, & Brown, 2006). A 2012 national survey of U.S. high school students found that about half (52%) knew a place on school grounds or near the school where students went to drink, use drugs or smoke, and over a third (36%) said it was very easy or fairly easy for students to do so during the school day without getting caught (The National Center on Addiction and Substance Abuse,
1
TIMI Study Group, Brigham and Women’s Hospital, Boston, MA, USA Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA 3 Center for Global Tobacco Control, Department of Social and Behavioral Sciences, Harvard School of Public Health, Boston, MA, USA 2
Corresponding Author: Olubode A. Olufajo, MD, MPH, Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA. Email: [email protected]
Downloaded from jsn.sagepub.com at UNIVERSITE LAVAL on November 18, 2015
Olufajo and Agaku
213
2012). Studies have shown indoor respirable-particle air pollution in some schools up to 32-fold higher than the National Ambient Air Quality Standards, even after the passing of smoking restriction laws (Lee et al., 2007). One of the objectives of Healthy People 2020 (Objective TU-15) is to make all U.S. middle and high schools 100% tobacco-free environments, including all school facilities, property, vehicles, and school events (USDHHS, 2013). Despite these developments, only limited nationally representative data exist on exposure to SHS among students while at school. This information is important to evaluate the effectiveness of the current school-based tobacco use prevention efforts from a national perspective and also to help formulate stronger measures to protect nonsmoking students and school personnel from SHS. Research done so far in this regard examined SHS exposure among students in a small geographic region, and hence lacks generalizability across the United States (Lee et al., 2007). Therefore, this study used a nationally representative sample of U.S. middle and high school students to assess prevalence and correlates of exposure to SHS at school during the year 2011.
Methods Data Source and Sample The National Youth Tobacco Survey (NYTS) is a biennial, repeated, cross-sectional survey of students enrolled in grades 6–12 in all the 50 U.S. states and the District of Columbia. The NYTS utilizes a three-stage cluster sampling procedure to generate nationally representative samples of U.S. middle and high school students. The NYTS oversamples Blacks, Hispanics, and Asians to ensure each racial/ethnic group is adequately represented, thereby increasing the precision of the estimates. Details of the methods and administration of the survey have been previously reported (Centers for Disease Control and Prevention, 2012). Data were adjusted for nonresponse and weighted. In 2011, 178 of the 214 eligible schools participated in the survey, yielding a school response rate of 83.2%. Also, 18,866 students completed the questionnaires of the 21,584 eligible students, yielding a student participation rate of 87.4%. The overall response rate was 72.7%.
SHS Exposure at School Exposure to SHS at school was assessed with the question: ‘‘During the past 7 days, on how many days did you breathe the smoke from someone who was smoking tobacco products at your school?’’ Possible answers ranged from ‘‘0 days’’ to ‘‘7 days.’’ Exposure to SHS at school was considered as any response other than ‘‘0 days.’’
Current and Peer Smoking Status Students were asked ‘‘During the past 30 days, on how many days did you smoke cigarettes?’’ Possible responses were ‘‘0
days,’’ ‘‘1 or 2 days,’’ ‘‘3 to 5 days,’’ ‘‘6 to 9 days,’’ ‘‘10 to 19 days,’’ ‘‘20 to 29 days,’’ or ‘‘All 30 days.’’ They were also asked, ‘‘How many of your closest friends smoke cigarettes?’’ Possible responses were ‘‘None,’’ ‘‘One,’’ ‘‘Two,’’ ‘‘Three,’’ ‘‘Four,’’ and ‘‘Not sure.’’ A current cigarette smoker was defined as a student who reported smoking cigarettes on at least one day during the prior 30 days. Peer smoking was defined as having one or more close friends who smoked cigarettes.
Perception About the Health Effects of SHS Exposure Perception of the health effects of SHS exposure was assessed with the question, ‘‘Do you think breathing smoke from other people’s cigarettes or other tobacco products is . . . ?’’ Possible responses were ‘‘Very harmful to one’s health,’’ ‘‘Somewhat harmful to one’s health,’’ ‘‘Not very harmful to one’s health,’’ or ‘‘Not harmful at all to one’s health.’’ Perception that SHS was harmful was defined as a response of ‘‘Very harmful to one’s health’’ or ‘‘Somewhat harmful to one’s health.’’ Responses of ‘‘Not very harmful to one’s health’’ and ‘‘Not harmful at all to one’s health’’ were considered as a perception of no harm from SHS exposure.
Sociodemographic Characteristics Sociodemographics assessed included sex (boy or girl), age (ranged from 9 years to 19 years or older), grade level (ranged from 6th to 12th grade), and race/ethnicity (Hispanics, non-Hispanic Whites, non-Hispanic Blacks, non-Hispanic Asians, non-Hispanic American Indian/Alaska Natives, and non-Hispanic Native Hawaiian/other Pacific Islanders). We categorized the ages to ‘‘9–12 years,’’ ‘‘13–16 years,’’ ‘‘17 years,’’ and the grade level to ‘‘middle school’’ or ‘‘high school.’’
Statistical Analysis Prevalence of SHS exposure at school was calculated overall and by age group, sex, school level, race/ethnic group, current smoking status, and peer smoking status. The variability of the estimates was assessed using 95% confidence intervals (CI). Tests for homogeneity between strata were carried out using w2 tests. A multivariate logistic regression model was fitted to assess correlates of SHS exposure at school using variables that showed significant association with SHS exposure on the univariate analysis (p < .05). The model adjusted for age, sex, current smoking status, peer smoking status, race/ethnicity, and perception of harm of SHS exposure, which were considered potential confounders. All statistical tests were two-tailed and the level of significance was set at the p < .05 level. All data were weighted to account for the complex survey design and were analyzed using Stata version 11 (StataCorp 2009: College Station, TX).
Downloaded from jsn.sagepub.com at UNIVERSITE LAVAL on November 18, 2015
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The Journal of School Nursing 31(3)
Table 1. Study Characteristics and Proportion of U.S. Middle and High School Students who Reported Secondhand Smoke (SHS) Exposure at School Within the Prior 7 Days in the 2011 National Youth Tobacco Survey. Number of people Proportion of overall Prevalence of SHS in subgroup population, % exposure, % [95% CI] p Value
Characteristics Overall Sex
Female Male Age, years 9–12 13–16 ≥ 17 School level Middle school (grades 6–8) High school (grades 9–12) ≥ 1 Close friend who smokes No Yes Current smoking status Nonsmoker Smoker Perception that SHS No exposure is harmful Yes Race/ethnicity White, non-Hispanic Black, non-Hispanic Asian, non-Hispanic Hispanic AI/AN, non-Hispanic NH/PI, non-Hispanic
8,737 8,700 3,369 10,320 3,816 8,325 9,110 10,347 5,108 15,291 1,839 1,317 14,919 7,308 3,264 568 5,747 286 73
49.1 50.9 18.2 60.1 21.7 43.3 56.7 67.5 32.5 89.2 10.8 7.9 92.1 60.2 14.7 3.5 20.3 .8 .5
25.7 [23.6, 27.1 [24.3, 24.2 [22.4, 17.2 [15.1, 26.4 [24.1, 30.8 [27.3, 18.1 [16.4, 31.5 [28.5, 16.2 [14.7, 45.1 [42.2, 21.1 [19.5, 59.1 [55.5, 35.8 [30.4, 24.6 [22.4, 25.4 [22.7, 24.0 [21.2, 21.1 [16.8, 28.4 [25.7, 32.2 [26.6, 31.7 [19.6,
27.8] 30.0] 26.1] 19.3] 28.7] 34.2] 19.7] 34.5] 17.7] 47.9] 22.8] 62.7] 41.2] 26.8] 28.1] 26.7] 25.5] 31.1] 37.7] 43.7]
.015
Assessment of Secondhand Smoke Exposure at School Among U.S. Middle and High School Students
The Journal of School Nursing 2015, Vol. 31(3) 212-218 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1059840514537075 jsn.sagepub.com
Olubode Ademola Olufajo, MD, MPH1,2, and Israel Terungwa Agaku, DMD, MPH3
Abstract To obtain nationally representative estimates of the prevalence of secondhand smoke (SHS) exposure at U.S. schools, we assessed the prevalence and correlates of SHS exposure at school among U.S. middle and high school students using data from the 2011 National Youth Tobacco Survey comprising of 18,866 students spread across all the U.S. states. Overall prevalence of SHS exposure at school was 25.7% (95% CI: [23.6%, 27.8%]). Multivariate logistic regression indicated that having ≥ 1 smoker friends (adjusted Odds Ratio [aOR] ¼ 2.92; p < .001); being a smoker (aOR ¼ 2.75; p < .001); and being aged 13–16 years, or ≥ 17 years (vs. 9–12 years) significantly increased the likelihood of SHS exposure. Understanding the health risks of SHS exposure alone did not seem to play a significant role in reducing exposure (aOR ¼ .89; p ¼ .342). These findings show there are significant levels of SHS exposure among students at U.S. middle and high schools, and sustained multipronged efforts are needed to reduce youth SHS exposure. Keywords National Youth Tobacco Survey, school, school nurses, secondhand smoke, students, tobacco control, youth
Secondhand smoke (SHS) exposure is responsible for over half a million deaths globally every year (Liu et al., 2013). SHS contains over 7,000 chemicals, including toxins and carcinogens that cause a wide range of diseases among nonsmokers, and no safe levels of exposure to SHS exist (U.S. Department of Health and Human Services [USDHHS], 2006). Health effects associated with SHS exposure include middle ear infections, nasal irritation, lower respiratory illnesses, decreased lung function, exacerbation of asthma, coronary heart disease, and various cancers (Song, Glantz, & Halpern-Felsher, 2009; USDHHS, 2006). SHS exposure is also known to be associated with increasing hospital visits, school absenteeism, rising medical ¨ berg, Woodcosts, and generally poorer health prospects (O ward, Peruga, & Pru¨ss-Ustu¨n, 2011; Saywell Jr, Zollinger, Lewis, Jay, & Spitznagle, 2013; USDHHS, 2006). Despite the proliferation of comprehensive state and local laws prohibiting smoking in public areas (Hopkins et al., 2012), the proportion of nonsmokers exposed to SHS remains high. Children and youth aged 0–15 years account for a large proportion of nonsmokers exposed to SHS in the ¨ berg et al., 2011), mostly from private United States (O environments such as the home and the family car (Cartmell et al., 2011). During 2003–2006, approximately 17.8% of U.S. youths aged 3–19 years were exposed to SHS in the home, while 29.8% of U.S. middle and high school students
reported exposure to SHS in a car during 2009 (King, Dube, & Tynan, 2012; Marano, Schober, Brody, & Zhang, 2009). The school environment is another potential area where youths may be exposed to SHS. The fact that youth are a high-risk group for the initiation and experimentation with tobacco products further increases the risk for SHS exposure in this age-group particularly in environments where youths congregate, such as at school (Leatherdale, McDonald, Cameron, Jolin, & Brown, 2006). A 2012 national survey of U.S. high school students found that about half (52%) knew a place on school grounds or near the school where students went to drink, use drugs or smoke, and over a third (36%) said it was very easy or fairly easy for students to do so during the school day without getting caught (The National Center on Addiction and Substance Abuse,
1
TIMI Study Group, Brigham and Women’s Hospital, Boston, MA, USA Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA 3 Center for Global Tobacco Control, Department of Social and Behavioral Sciences, Harvard School of Public Health, Boston, MA, USA 2
Corresponding Author: Olubode A. Olufajo, MD, MPH, Department of Epidemiology, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115, USA. Email: [email protected]
Downloaded from jsn.sagepub.com at UNIVERSITE LAVAL on November 18, 2015
Olufajo and Agaku
213
2012). Studies have shown indoor respirable-particle air pollution in some schools up to 32-fold higher than the National Ambient Air Quality Standards, even after the passing of smoking restriction laws (Lee et al., 2007). One of the objectives of Healthy People 2020 (Objective TU-15) is to make all U.S. middle and high schools 100% tobacco-free environments, including all school facilities, property, vehicles, and school events (USDHHS, 2013). Despite these developments, only limited nationally representative data exist on exposure to SHS among students while at school. This information is important to evaluate the effectiveness of the current school-based tobacco use prevention efforts from a national perspective and also to help formulate stronger measures to protect nonsmoking students and school personnel from SHS. Research done so far in this regard examined SHS exposure among students in a small geographic region, and hence lacks generalizability across the United States (Lee et al., 2007). Therefore, this study used a nationally representative sample of U.S. middle and high school students to assess prevalence and correlates of exposure to SHS at school during the year 2011.
Methods Data Source and Sample The National Youth Tobacco Survey (NYTS) is a biennial, repeated, cross-sectional survey of students enrolled in grades 6–12 in all the 50 U.S. states and the District of Columbia. The NYTS utilizes a three-stage cluster sampling procedure to generate nationally representative samples of U.S. middle and high school students. The NYTS oversamples Blacks, Hispanics, and Asians to ensure each racial/ethnic group is adequately represented, thereby increasing the precision of the estimates. Details of the methods and administration of the survey have been previously reported (Centers for Disease Control and Prevention, 2012). Data were adjusted for nonresponse and weighted. In 2011, 178 of the 214 eligible schools participated in the survey, yielding a school response rate of 83.2%. Also, 18,866 students completed the questionnaires of the 21,584 eligible students, yielding a student participation rate of 87.4%. The overall response rate was 72.7%.
SHS Exposure at School Exposure to SHS at school was assessed with the question: ‘‘During the past 7 days, on how many days did you breathe the smoke from someone who was smoking tobacco products at your school?’’ Possible answers ranged from ‘‘0 days’’ to ‘‘7 days.’’ Exposure to SHS at school was considered as any response other than ‘‘0 days.’’
Current and Peer Smoking Status Students were asked ‘‘During the past 30 days, on how many days did you smoke cigarettes?’’ Possible responses were ‘‘0
days,’’ ‘‘1 or 2 days,’’ ‘‘3 to 5 days,’’ ‘‘6 to 9 days,’’ ‘‘10 to 19 days,’’ ‘‘20 to 29 days,’’ or ‘‘All 30 days.’’ They were also asked, ‘‘How many of your closest friends smoke cigarettes?’’ Possible responses were ‘‘None,’’ ‘‘One,’’ ‘‘Two,’’ ‘‘Three,’’ ‘‘Four,’’ and ‘‘Not sure.’’ A current cigarette smoker was defined as a student who reported smoking cigarettes on at least one day during the prior 30 days. Peer smoking was defined as having one or more close friends who smoked cigarettes.
Perception About the Health Effects of SHS Exposure Perception of the health effects of SHS exposure was assessed with the question, ‘‘Do you think breathing smoke from other people’s cigarettes or other tobacco products is . . . ?’’ Possible responses were ‘‘Very harmful to one’s health,’’ ‘‘Somewhat harmful to one’s health,’’ ‘‘Not very harmful to one’s health,’’ or ‘‘Not harmful at all to one’s health.’’ Perception that SHS was harmful was defined as a response of ‘‘Very harmful to one’s health’’ or ‘‘Somewhat harmful to one’s health.’’ Responses of ‘‘Not very harmful to one’s health’’ and ‘‘Not harmful at all to one’s health’’ were considered as a perception of no harm from SHS exposure.
Sociodemographic Characteristics Sociodemographics assessed included sex (boy or girl), age (ranged from 9 years to 19 years or older), grade level (ranged from 6th to 12th grade), and race/ethnicity (Hispanics, non-Hispanic Whites, non-Hispanic Blacks, non-Hispanic Asians, non-Hispanic American Indian/Alaska Natives, and non-Hispanic Native Hawaiian/other Pacific Islanders). We categorized the ages to ‘‘9–12 years,’’ ‘‘13–16 years,’’ ‘‘17 years,’’ and the grade level to ‘‘middle school’’ or ‘‘high school.’’
Statistical Analysis Prevalence of SHS exposure at school was calculated overall and by age group, sex, school level, race/ethnic group, current smoking status, and peer smoking status. The variability of the estimates was assessed using 95% confidence intervals (CI). Tests for homogeneity between strata were carried out using w2 tests. A multivariate logistic regression model was fitted to assess correlates of SHS exposure at school using variables that showed significant association with SHS exposure on the univariate analysis (p < .05). The model adjusted for age, sex, current smoking status, peer smoking status, race/ethnicity, and perception of harm of SHS exposure, which were considered potential confounders. All statistical tests were two-tailed and the level of significance was set at the p < .05 level. All data were weighted to account for the complex survey design and were analyzed using Stata version 11 (StataCorp 2009: College Station, TX).
Downloaded from jsn.sagepub.com at UNIVERSITE LAVAL on November 18, 2015
214
The Journal of School Nursing 31(3)
Table 1. Study Characteristics and Proportion of U.S. Middle and High School Students who Reported Secondhand Smoke (SHS) Exposure at School Within the Prior 7 Days in the 2011 National Youth Tobacco Survey. Number of people Proportion of overall Prevalence of SHS in subgroup population, % exposure, % [95% CI] p Value
Characteristics Overall Sex
Female Male Age, years 9–12 13–16 ≥ 17 School level Middle school (grades 6–8) High school (grades 9–12) ≥ 1 Close friend who smokes No Yes Current smoking status Nonsmoker Smoker Perception that SHS No exposure is harmful Yes Race/ethnicity White, non-Hispanic Black, non-Hispanic Asian, non-Hispanic Hispanic AI/AN, non-Hispanic NH/PI, non-Hispanic
8,737 8,700 3,369 10,320 3,816 8,325 9,110 10,347 5,108 15,291 1,839 1,317 14,919 7,308 3,264 568 5,747 286 73
49.1 50.9 18.2 60.1 21.7 43.3 56.7 67.5 32.5 89.2 10.8 7.9 92.1 60.2 14.7 3.5 20.3 .8 .5
25.7 [23.6, 27.1 [24.3, 24.2 [22.4, 17.2 [15.1, 26.4 [24.1, 30.8 [27.3, 18.1 [16.4, 31.5 [28.5, 16.2 [14.7, 45.1 [42.2, 21.1 [19.5, 59.1 [55.5, 35.8 [30.4, 24.6 [22.4, 25.4 [22.7, 24.0 [21.2, 21.1 [16.8, 28.4 [25.7, 32.2 [26.6, 31.7 [19.6,
27.8] 30.0] 26.1] 19.3] 28.7] 34.2] 19.7] 34.5] 17.7] 47.9] 22.8] 62.7] 41.2] 26.8] 28.1] 26.7] 25.5] 31.1] 37.7] 43.7]
.015
