HEALTH EDUCATION RESEARCH
Vol.25 no.5 2010 Pages 748–756 Advance Access publication 2 April 2010
Associations between schools’ tobacco restrictions and adolescents’ use of tobacco
Simon Øverland1*, Leif Edvard Aarø1,2 and Rita Lill Lindbak3 1
Research Centre for Health Promotion, Faculty of Psychology, University of Bergen, N-5015 Bergen, Norway, 2Division of Mental Health, National Institute of Public Health, N-0403 Oslo, Norway and 3Department for Healthy Public Policy, Norwegian Directorate of Health, N-0130 Oslo, Norway *Correspondence to: S. Øverland. E-mail:
[email protected] Received on September 23, 2009; accepted on March 5, 2010
Abstract
Introduction
Schools are an important arena for smoking prevention. In many countries, smoking rates have been reduced among adolescents, but the use of smokeless tobacco is on the rise in some of these countries. We aimed to study the associations between schools’ restrictions on smoking and snus and on the use of these tobacco products among students in upper secondary school. We employed data from a national representative study of 1444 Norwegian students, aged 16–20 years. Respondents were asked about their schools’ restrictions on snus and smoking and own use of these products. We examined associations between restrictions and the use, controlling for age, gender, type of school and regional differences. We found clear consistent associations between schools’ restrictions on tobacco use and less use of these products. More explicit pervasive restrictions were strongly associated with the prevalence of use. This first study on the associations between schools’ restrictions on snus and the prevalence of snus use corroborate what has been found in many studies on smoking restrictions and smoking. Strict school tobacco policies may be an important tool if health authorities are interested in implementing measures to limit or reduce snus use among adolescents.
Schools are one of the main arenas for public health interventions, not least with a view to health behaviour. As a major public health issue, smoking has been the target of numerous school-based interventions, many of which have involved information campaigns to influence cognitions, emotions and attitudes towards smoking, with the ultimate goals of modifying smoking behaviour and improving health. A comprehensive review from 2006 suggests that approaches based on information alone may lead to short-term reductions in smoking rates but that long-term effects seem to require more coherent programmes [1]. Legislation and policies regulating access to and the availability of tobacco products and smoking behaviour have also been important tools for tobacco control. Schools have been a natural arena for implementing restrictions to combat adolescents’ smoking, but there is a lack of consensus in the literature about the effect of school smoking policies on smoking prevalence among students. A review article from 2004 presented mixed evidence regarding the effect of school smoking policies on students’ smoking [2]. Studies published after this have maintained this impression, as some have failed to find associations between smoking and school smoking policies [3, 4], while others have found mixed results [5, 6], and yet others have found clear support for an association [4, 7, 8]. Most studies of the association between school policies and smoking have measured
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doi:10.1093/her/cyq023
Schools’ restrictions and tobacco usage school policies as reported by staff. It has been argued that eliciting students’ perspectives on smoking in the school arena should provide additional knowledge about this relationship [9–11]. The prevalence of smoking among Norwegian adolescents has decreased more rapidly in recent decades [12]. As the downward trajectory of smoking among young people has gained momentum, it has been accompanied by more use of smokeless tobacco, especially in the form of snus (a smokeless tobacco product consisting of moist powder tobacco consumed by placing it under the lip) [13]. In one study, Boyle et al. [14] found that the expectation of mild sanctions on the part of schools and parents was associated with more use of smokeless tobacco but, beyond this, we are not aware of any studies that examine the effect of school policies on snus and how the policies impact the prevalence of use. In the Norwegian school system, smoking indoors is prohibited by law. Local and/or regional school authorities may also ban outdoor smoking on school grounds. They are encouraged to do so by the Ministries of Health and Education, but there is no harmonized legislation to regulate smoking outdoors at Norwegian schools. The use of smokeless tobacco in public places is not regulated under Norwegian law, and regulations regarding use at schools are entirely at the discretion of the regional school authorities. Snus and cigarettes are widely available for sale in Norway and can be purchased from the age of 18 years. In the present study, we have employed a representative sample of Norwegian students in upper secondary schools to examine the association between school restrictions on smoking and the use of snus and the prevalence of smoking and the use of snus. As opposed to many previous papers on the topic, we have asked the students themselves about school restrictions on tobacco use to elicit information about the restrictions as perceived by the students themselves.
Methods The data used in the present study have been excerpted from a more comprehensive survey on
tobacco use and related topics among Norwegian adolescents and young adults aged 16–20 years. The survey was funded by the Norwegian Directorate of Health. To reach the predefined sample size of 2400 respondents, a sample of 5000 potential respondents was established through random draw from the Norwegian population registry, within predefined strata defined by age, gender and geographical distribution among the source population. A letter was sent to these potential respondents, containing a brief description of the study and the interview procedure involved, informing them that participation would qualify them to enter a drawing for 10 gift certificates worth NOK 500 (Norwegian kroner, about £50) each.
Data collection procedure The data were collected during 2 weeks starting in mid-September 2007 by a commercial marketing research institute (Synovate MMI Inc.), using telephone interviews. First, phone numbers were obtained for the 5000 potential respondents. Multiple numbers for some of them resulted in a total of 5757 phone numbers. Of these, 338 numbers were faulty or did not lead to the right person. During the interview process, calls were made in a computerassisted sequence to consistently maintain the representativeness of the sample. Of all the calls made, 1246 were not answered, while a total of 1188 calls were answered but the individuals declined to be interviewed. As planned, data collection stopped when the predefined sample of 2400 respondents was obtained and then the 15 more interviews were carried out to ensure an even distribution of respondents across age, regions and gender, bringing the total sample to 1211 males and 1204 females. Of the initial 5757 phone numbers, 570 were redundant and never used. The sample was checked for representativeness against the population registry after completion of the interview process. Finally, of this total sample of 2415, we excluded 971 individuals who were not upper secondary school students at the time. That left a final sample of 1444 individuals: 702 males (48.6%) and 742 females (51.4%). To further check for representativeness, the sample distribution across upper 749
S. Øverland et al. secondary school types was validated against national statistics.
Variables The students were asked to specify whether they attended a general or a vocational upper secondary school. In Norway, general upper secondary schools emphasize theoretical subjects (social studies, math, history, etc.), while vocational upper secondary schools focus less on theory and more on practical teaching aimed at developing skills relevant to specific occupations, such as bookkeepers, carpenters, electricians and so forth. Respondents’ own tobacco habits were measured through questions aimed at each product by first asking: ‘Have you ever smoked (cigarettes)/tried snus?’ If yes, the respondent was asked: ‘How often do you currently smoke (cigarettes)/use snus?’ with multiple-choice answers provided (frequencies in parentheses): ‘daily’, ‘weekly’, ‘less than once a week’ or ‘not at all’. Relatively, few reported weekly use. In a previous study, those who reported smoking weekly reported an average of 10 cigarettes a week. Accordingly, in agreement with the previous operationalization of user status in this age group [13], those who reported using snus and/or smoking daily or weekly were grouped together as ‘snus users’ and ‘smokers’. The main exposure variable is defined as schools’ restrictions on tobacco consumption. As regards smoking, the students were presented with the following four statements on smoking restrictions: ‘Students may smoke at the entrance to school premises’, ‘Students are allowed to smoke on school grounds, outside school buildings’, ‘Students and teachers smoke together on or near school premises’ and ‘Students are not allowed to smoke during school hours’. For each of these statements, the students were asked to rate how well the statement applied to their school’s restrictions on a scale from (i) Applies very well, (ii) Applies fairly well, (iii) Does not apply well, to (iv) Does not apply at all. There was also a fifth ‘Don’t know’ option. The few (range: 0.1–2.6%) who responded ‘Don’t know’ on an item were then exempted from further analyses of that item. The correlations between the 750
items on smoking restrictions ranged between 0.26 and 0.04. As regards schools’ restrictions on snus, the students were asked if they were allowed to use snus on school grounds and if they were allowed to use snus during class (response categories: ‘yes’, ‘no’ and ‘I don’t know’). We also had one statement similar to those on smoking: ‘Students are not allowed to use snus during school hours’. In the same way as for smoking, we omitted those who responded that they were not familiar with their school’s restrictions on snus (range: 5.2–6.0%). As a result of excluding those who lacked responses/‘don’t know’, the number of respondents in the analyses of the different statements (as seen in Tables I–III) varies. The correlation coefficients between the items on snus restrictions ranged between 0.30 and 0.16. These measures of school restrictions were checked for internal consistency and were found to be generally consistent.
Statistical analysis First, we looked at overall rates of smoking and snus use and used chi-square tests to determine whether user rates differed between general and vocational upper secondary schools. Second, we used respondents’ answers to the statements on smoking and snus restrictions to look for differences between the two types of upper secondary schools. In the main analyses, we examined the association between school restrictions and smoking and snus use, employing logistic regression analysis to adjust for the type of upper secondary school. Snus use is much more common among males and it would be expected to increase with age in such a cohort of young adults. There may also be regional differences in smoking and snus use rates, as well as in school restrictions. The logistic regression analyses were therefore adjusted for age, gender, type of school and region. Finally, we ran an interaction analysis to examine whether there were significant differences in the associations between the statements and smoking/snus use by school type. The interaction was tested in regression models where the statements and school types were entered as predictors of either snus use or
Schools’ restrictions and tobacco usage smoking, and the interaction term between the statement and school type was entered as step two in the regression model. The test for significance was whether there was an increase in explained variance upon entering the interaction term.
Results Of the 1444 respondents, 182 (12.6%) reported smoking daily or weekly (12.1% of the males and 13.1% of the females), while 195 (13.5%) reported using snus daily or weekly (20.4% of the males and 7.0% of the females). A higher rate of smokers was observed among students in vocational upper secondary schools (19.5%) than in general upper secondary schools (8.1%) (chi-square = 40.7, df = 1, P < 0.001), while the rates of snus users were similar across the school types (12.9 and 14.4%, respectively, chi-square = 0.6, df = 1, P = 0.41). There was an overall trend of somewhat softer restrictions on smoking and snus use at vocational upper secondary schools than at the general upper secondary schools (Table I). There was no significant difference in the rate of snus use and restrictions on snus use on school premises (Table II). However, students who reported that snus use was allowed in class at their school were about three times as likely to also report using snus daily or weekly [odds ratio (OR) = 2.9]. Adjusted for type of school, gender and age, the odds of snus use remained more than twice as high as those for students not allowed to use snus in class (OR = 2.3). The highest association was found for the statement that snus use was completely banned during school hours. Compared with those who confirmed that such a restriction applied very well to their school, students who reported that the statement did not apply at all had adjusted OR of using snus themselves of OR = 2.5 (Table II). We also found an association between schools’ smoking restrictions and smoking rates. Restrictions on smoking outside the school entrance and generally outdoors on school grounds both correlated moderately with smoker rates. Those who agreed with statements that smoking was allowed
at specified sites at their school had adjusted ORs for smoking of 1.9 (same results for both statements), compared with those who reported that this did not apply at all at their school. The presence or absence of a general prohibition on smoking during school hours had a stronger association with smoking rates; those who reported that such an absolute prohibition did not apply at all to their school had an adjusted OR for smoking of 3.4 (Table III), compared with those who reported that smoking prohibition applied at their school. The highest adjusted OR (OR = 3.5) for smoking was found among those who reported that students and teachers smoking together applied at their school (Table III). As a sensitivity analysis to validate the results, we ran all analyses again with an outcome variable including those reporting snus use/smoking less than once a week among the smokers/snus users. The results were as expected qualitatively similar but a bit weaker (results not shown). There were no significant interactions between any of the restriction statements and types of schools with a view to predicting smoking and snus use.
Discussion Main findings We found that respondents’ reports on restrictions on snus use and smoking at school were associated with their likelihood of being a smoker or snus user themselves. This association remained after controlling for respondents’ age and gender, what type of school they attended and the region of Norway in which they lived. Across the items, there was a trend indicating that the stricter the school regulations on tobacco use, the stronger the association with students’ use of tobacco products.
Strengths and limitations The respondents in the study were randomly selected using the Norwegian population registry. Recruitment procedures were employed to ensure a representative sample of Norwegian 16- to 20year-olds. To the best of our knowledge, this is the first study that has included measures of 751
S. Øverland et al. Table I. Smoking and snus use policies in general and vocational upper secondary schools All N Are you allowed to use snus on school premises? Yes No Are you allowed to use snus in class at your school? Yes No Students are not allowed to use snus during school hours Applies very well Applies fairly well Does not apply well Does not apply at all Students are allowed to smoke outside the school entrance Applies very well Applies fairly well Does not apply well Does not apply at all Students are allowed to smoke in outdoor areas at school Applies very well Applies fairly well Does not apply well Does not apply at all Students and teachers smoke together at school Applies very well Applies fairly well Does not apply well Does not apply at all Students are not allowed to smoke during school hours Applies very well Applies fairly well Does not apply well Does not apply at all
%
General UPS
Vocational UPS
N
N
%
Comparison
% v2 = 2.6, df = 1, P = 0.11
638 692
48.0 52.0
365 426
46.1 53.9
273 266
50.6 49.4 v2 = 6.6, df = 1, P = 0.01
237 1104
17.7 82.3
124 677
15.5 84.5
113 427
20.9 79.1 v2 = 9.9, df = 3, P = 0.02
439 188 320 439
31.7 13.6 23.1 31.7
288 112 179 249
34.8 13.5 21.6 30.1
151 76 141 190
27.1 13.6 25.3 34.1 v2 = 2.6, df = 3, P = 0.46
207 87 228 892
14.6 6.2 16.1 63.1
128 57 139 519
15.2 6.8 16.5 61.6
79 30 89 373
13.8 5.3 15.6 65.3 v2 = 10.7, df = 3, P < 0.05
448 209 227 524
31.8 14.8 16.1 37.2
240 133 137 330
28.6 15.8 16.3 39.3
208 76 90 194
36.6 13.4 15.8 34.2 v2 = 60.1, df = 3, P < 0.001
271 163 305 638
19.7 11.8 22.1 46.3
111 94 174 436
13.6 11.5 21.3 53.5
160 69 131 202
28.5 12.3 23.3 35.9 v2 = 12.5, df = 3, P < 0.01
427 137 300 541
30.4 9.8 21.4 38.5
280 87 163 307
33.5 10.4 19.5 36.7
147 50 137 234
25.9 8.8 24.1 41.2
UPS = upper secondary school.
schools’ restrictions on snus use as well as on smoking. Also, it should be considered a strength that this study addresses students’ perceptions of tobacco restrictions since other papers have emphasized the insufficiency of looking at policies or written rules rather than looking at the extent to which they are enforced [5]. 752
Selective non-participation is a potential limitation of the study. There were about as many who declined to participate (n = 1246) as individuals the interviewers were unable reach (n = 1188). The reasons for not reaching certain people from the calling list are believed to be largely trivial when it comes to the introduction of biases. If we ignore
Schools’ restrictions and tobacco usage Table II. Snus use (daily or weekly versus less or no snus use) by school policy School policy on snus
Rates of snus use, %
Are you allowed to use snus on school premises? No (n = 692) 12.6 Yes (n = 638) 15.8 Are you allowed to use snus in class at your school? No (n = 1104) 11.0 Yes (n = 237) 26.6 Students are not allowed to use snus during school hours Applies very well (n = 439) 8.4 Applies fairly well (n = 188) 9.6 Does not apply well (n = 320) 12.8 Does not apply at all (n = 439) 21.0
Crude OR (95% CI)
Adjusted OR (95% CI)
Ref. 1.3 (1.0–1.8)
Ref. 1.2 (0.9–1.7)
Ref. 2.9 (2.1–4.2)
Ref. 2.3 (1.6–3.3)
Ref. 1.2 (0.6–2.1) 1.6 (1.0–2.6) 2.9 (1.9–4.3)
Ref. 1.3 (0.7–2.3) 1.5 (0.9–2.5) 2.5 (1.7–3.8)
Crude associations (percentages and ORs) and adjusted ORs (controlled for type of school, gender, age and region) based on multiple logistic regression analyses.
Table III. Smoking (daily or weekly versus less or no smoking) by school policy School policy on smoking
Smoker rates, %
Students are allowed to smoke outside the school entrance Does not apply at all (n = 892) 11.4 Does not apply well (n = 227) 13.2 Applies fairly well (n = 87) 11.5 Applies very well (n = 206) 18.4 Students are allowed to smoke in outdoor areas at school Does not apply at all (n = 523) 10.9 Does not apply well (n = 227) 8.8 Applies fairly well (n = 209) 9.1 Applies very well (n = 448) 18.8 Students and teachers smoke together at school Does not apply at all (n = 637) 7.5 Does not apply well (n = 304) 10.5 Applies fairly well (n = 163) 16.0 Applies very well (n = 271) 26.6 Students are not allowed to smoke during school hours Applies very well (n = 426) 6.8 Applies fairly well (n = 137) 8.0 Does not apply well (n = 299) 9.7 Does not apply at all (n = 541) 20.5
Crude OR (95% CI)
Adjusted OR (95% CI)
Ref. 1.2 (0.8–1.8) 1.0 (0.5–2.0) 1.8 (1.2–2.6)
Ref. 1.3 (0.8–2.0) 1.2 (0.6–2.4) 1.9 (1.2–2.9)
Ref. 0.8 (0.5–1.3) 0.8 (0.5–1.4) 1.9 (1.3–2.7)
Ref. 0.9 (0.5–1.5) 0.9 (0.5–1.5) 1.9 (1.3–2.8)
Ref. 1.4 (0.9–2.3) 2.3 (1.4–3.9) 4.4 (3.0–6.6)
Ref. 1.3 (0.8–2.1) 2.0 (1.2–3.4) 3.5 (2.3–5.2)
Ref. 1.2 (0.6–2.5) 1.5 (0.9–2.5) 3.5 (2.3–5.4)
Ref. 1.3 (0.6–2.6) 1.4 (0.8–2.5) 3.4 (2.2–5.2)
Crude associations (percentages and ORs) and adjusted ORs (controlled for type of school, gender, age and region) from multiple logistic regression analyses.
those who do not answer phone calls from unknown numbers, this would translate into a response rate of 67%, but regarding failure to respond as nonparticipation would translate into a response rate of 49.8%. The prevalence of smokers and snus users was as expected from comparable studies [12], and
the general and gender-specific distribution of students across school type was coherent with national statistics. To the best of our knowledge, there are no indications of biases resulting from systematic nonparticipation that would alter the conclusions drawn from this study. 753
S. Øverland et al. We asked respondents about snus and smoking restrictions at their schools. We do not know the extent to which same-school students gave consistent reports about their schools’ tobacco regulations, and we have not had access to objective data on the schools’ written rules or policies. Consequently, we cannot discount the possibility that some students gave reports on their schools’ restrictions that harmonized with their own tobacco habits. Given the trend that emerged from our results (more smoking and snus use where there are softer restrictions), such biased reporting of restrictions could have led us to overestimate the association between restrictions and tobacco use. It should, however, be noted that very few resorted to the ‘Don’t know’ category, especially in connection with statements about smoking restrictions. This should indicate that most students are aware of the relevant restrictions at their schools and are able to report them with some confidence. The association between restrictions and smoking/snus use could be confounded by socio-economic status. However, the variable ‘type of school’ should serve as a crude, but relevant, indicator of socio-economic status [15], and adjustment for this had very little impact. As a general limitation, it is also important to note that our cross-sectional design precludes any firm conclusions on causality. As a final limitation, we do not know what other activities schools carry out with a view to smoking and snus use. It is possible that the schools with the most restrictive policies also run other programmes designed to reduce the prevalence of smoking and snus use. As such, the association between school restrictions and prevalence of use may be confounded by the presence of other programmes directed at reducing tobacco use among students. However, a recent study found support for an effect of school restrictions on smoking, beyond the impact of community norms such as those described above [16].
Interpretation Despite the limitations, our results suggest that school restrictions on smoking are related to smoking prevalence among the students. This main result 754
is commensurate with previous investigations that have also found associations between school policies and student smoking [7, 11, 17]. Moore et al. [17] found that more restrictive policies have a stronger association with smoking prevalence. In the present study, we found a stronger negative association between smoking and an absolute smoking ban during school hours than for less pervasive restrictions on smoking, such as smoking bans related to particular areas of the school grounds. These results are seemingly in conflict with Darling et al. [3], who found no association between schools’ written smoking policies and smoking, irrespective of policy strength. The authors remarked that their study was limited by the lack of information on policy implementation. In the present study, the information on schools’ restrictions was gathered from the students themselves. Students’ reports should be a result of the implementation and dissemination of the policies, and this discrepancy might explain why the results diverge. A recent study by Lovato et al. [5] supports this interpretation as they found that smoking was not associated with schools’ policy intentions but was rather a clear correlate of students’ perceptions of school tobacco policies. This is also in line with previous reports that emphasize the role of enforcement regardless of the written policies schools might have [11, 17, 18]. The strongest association with smoking in the present study was found between the statement about students and teachers smoking together and own smoking. In a study conducted in the United states, Barnett et al. [6] found that students in schools where the staff were allowed to smoke outdoors were five times more likely to smoke than students at schools where such practices were not allowed. A German study among 16- to 21-year-old students also found that teachers’ smoking on school grounds correlated with students’ smoking [7]. These results suggest that teacher-to-student social influences have a strong impact on students’ smoking behaviour. Taken together with studies showing that students’ exposure to teachers’ smoking varies [19], but given that this factor can be modified by national tobacco control policies
Schools’ restrictions and tobacco usage [20], this finding should inspire legislative efforts regarding school policies on smoking. To the best of our knowledge, this is the first study to examine the relationship between schools’ snus restrictions and the use of snus among students. As for smoking, we found a stronger association between use and a total ban on snus use during school hours than with more detailed restrictions dictating where snus is allowed at school. Since this was found for snus use and smoking alike, it could mean that a simple straightforward policy that bans all use gives a clearer signal, is easier to implement and enforce and is more likely to result in less use of tobacco products among students. Also, as we failed to identify any significant interactions between school restrictions and type of school in the prediction of smoking and snus use, our findings indicate that such restrictions should be equally effective, at least in these types of schools, despite differences in their student populations. Students at general schools tend to continue on to colleges and universities and to be recruited into whitecollar jobs in adult life, while students at vocational schools more often pursue blue-collar occupations. Since restrictions on smoking seem to be just as strongly associated with less smoking in vocational schools as in general upper secondary schools, such restrictions may, in the long term, contribute to reduce increasing differences in smoking prevalence between high status and low status segments of the population [21–23]. This is consistent with the general idea that restrictive measures are effective across all groups defined by socio-economic status. This must, however, be generalized with caution if related to populations in countries with other kinds of school systems where differences between student populations are greater than in our sample. These new findings about snus may be particularly valuable in two respects: first, snus use in adolescents has seen a strong increase among Norwegian adolescents in recent years [12, 13]. Although snus is considered to be far less harmful than smoking [24], we may need to implement strategies to reduce the onset of snus use among adolescents. At present, it seems that adolescents overestimate the harmfulness of snus, at least when compared with
the harmfulness of smoking [25]. Consequently, there is a risk that the provision of balanced accurate health information about snus might increase rather than decrease the use of this product. This potential drawback of health information as a means to curb the rising incidence of snus use may serve to enhance the importance of tools such as school restrictions. Second, our findings on snus parallel those on smoking. This fact provides corroborating evidence. Findings that school restrictions have an impact on two different products should lend support to the notion that school restrictions do indeed have an impact on health behaviour in this age group.
Funding Norwegian Directorate of Health. Acknowledgements Ethics Committee approval: The study protocol was presented for the Regional Committee for Medical Research Ethics (REK-Vest) and was carried out within the general permits of Synovate MMI Inc. The sample of respondents was drawn from the Norwegian population registry with approval from the Norwegian Tax Administration.
Conflict of interest statement None declared. References 1. Thomas RE, Perera R. School-based programmes for preventing smoking. Cochrane Database of Systematic Reviews. Chichester, UK: John Wiley & Sons, Ltd, 2006. 2. Aveyard P, Markham WA, Cheng KK. A methodological and substantive review of the evidence that schools cause pupils to smoke. Soc Sci Med 2004; 58: 2253–65. 3. Darling H, Reeder AI, Williams S et al. Is there a relation between school smoking policies and youth cigarette smoking knowledge and behaviors? Health Educ Res 2006; 21: 108–15. 4. Poulin CC. School smoking bans: do they help/do they harm? Drug Alcohol Rev 2007; 26: 615–24. 5. Lovato CY, Sabiston CM, Hadd V et al. The impact of school smoking policies and student perceptions of
755
S. Øverland et al.
6. 7. 8. 9. 10.
11. 12. 13. 14. 15. 16.
enforcement on school smoking prevalence and location of smoking. Health Educ Res 2007; 22: 782–93. Barnett TA, Gauvin L, Lambert M et al. The influence of school smoking policies on student tobacco use. Arch Pediatr Adolesc Med 2007; 161: 842–8. Piontek D, Buehler A, Rudolph U et al. Social contexts in adolescent smoking: does school policy matter? Health Educ Res 2008; 23: 1029–38. Østhus S, Pape H, Lund KE. Smoking restrictions and smoking prevalence in high schools. Tidsskr Nor Lægeforen 2007; 127: 1192–4. Turner KM, Gordon J. A fresh perspective on a rank issue: pupils’ accounts of staff enforcement of smoking restrictions. Health Educ Res 2004; 19: 148–58. Baillie LE, Lovato CY, Taylor E et al. The pit and the pendulum: the impact on teen smokers of including a designated smoking area in school tobacco control policy. Health Educ Res 2008; 23: 1008–15. Lipperman-Kreda S, Paschall MJ, Grube JW. Perceived enforcement of school tobacco policy and adolescents’ cigarette smoking. Prev Med 2009; 48: 562–6. Aarø LE, Lindbak RL, Øverland S et al. Use of tobacco among Norwegian pupils in secondary school 1975-2005. Tidsskr Nor Lægeforen 2008; 128: 1815–9. Øverland S, Hetland J, Aarø LE. A study of adolescent smoking and use of snus in 2004 and 2007. Tidsskr Nor Lægeforen 2008; 128: 1820–4. Boyle RG, Claxton AJ, Forster JL. The role of social influences and tobacco availability on adolescent smokeless tobacco use. J Adolesc Health 1997; 20: 279–85. Øverland S, Tjora T, Hetland J et al. Associations between adolescent socioeducational status and use of snus and smoking. Tob Control 2010. In press. Lipperman-Kreda S, Grube JW. Students’ perception of community disapproval, perceived enforcement of school
756
17.
18.
19. 20.
21. 22. 23.
24.
25.
antismoking policies, personal beliefs, and their cigarette smoking behaviors: results from a structural equation modeling analysis. Nicotine Tob Res 2009; 11: 531–9. Moore L, Roberts C, Tudor-Smith C. School smoking policies and smoking prevalence among adolescents: multilevel analysis of cross-sectional data from Wales. Tob Control 2001; 10: 117–23. Wakefield MA, Chaloupka FJ, Kaufman NJ et al. Effect of restrictions on smoking at home, at school, and in public places on teenage smoking: cross sectional study. Br Med J 2000; 321: 333–7. Warren CW, Grp GC. The Global School Personnel Survey: a cross-country overview. Tob Control 2006; 15: II20–30. Wold B, Torsheim T, Currie C et al. National and school policies on restrictions of teacher smoking: a multilevel analysis of student exposure to teacher smoking in seven European countries. Health Educ Res 2004; 19: 217–26. Franks P, Jerant AF, Leigh JP et al. Cigarette prices, smoking, and the poor: implications of recent trends. Am J Public Health 2007; 97: 1873–7. Peretti-Watel P, Constance J, Seror V et al. Cigarettes and social differentiation in France: is tobacco use increasingly concentrated among the poor? Addiction 2009; 104: 1718–28. Jefferis B, Power C, Graham H et al. Changing social gradients in cigarette smoking and cessation over two decades of adult follow-up in a British birth cohort. J Public Health 2004; 26: 13–8. Levy DT, Mumford EA, Cummings KM et al. The relative risks of a low-nitrosamine smokeless tobacco product compared with smoking cigarettes: estimates of a panel of experts. Cancer Epidemiol Biomarkers Prev 2004; 13: 2035–42. Øverland S, Hetland J, Aarø LE. Relative harm of snus and cigarettes: what do Norwegian adolescents say? Tob Control 2008; 17: 422–5.
