A12.1.4 What makes an effective health warning?

While the characteristics of effective warnings labels have been extensively studied for many years for hazardous chemical products and for pharmaceuticals1 study of the optimal design of warnings for cigarettes and other tobacco products is a relatively young field.

Research on the effects of health warnings on cigarettes can be divided into research on the content of the warnings and research on the form. There is more direct research on form, while much of the knowledge we have about the effects of content is either from analogue studies done when considering which warnings to implement, or from other areas of communication research not specifically related to warnings about tobacco on packs in the marketplace.

A12.1.4.1 What should warnings cover?

To fully inform consumers about the health consequence of smoking, warnings need to cover all the important health risks and give consumers enough information to fully understand all the material issues relevant to those risks. People need to understand not just that risk increases, but also what contracting a disease would mean not just to their longevity but also to the day-to-day quality of their life … not just the risk of contracting a disease but also the lived effects of currently available treatments, and the likely prognosis. Conveying such information is not straight-forward, because smokers bring to the 'sender–receiver' relationship a whole host of preconceived knowledge and ideas and self-protective and self-exempting beliefs and reactions.

A review of theories and evidence, largely from social psychology2 suggests that warnings are more likely to be effective in increasing understanding of tobacco-related risk if they:

  • take into account the relevant attitudes of the consumers who use tobacco productsi
  • combine information that is likely to invoke strong fear responses with information about how risk can be avoided
  • convey a sense of the social as well as the physical consequence of negative health effects
  • promote discussion about smoking among smokers friends and family
  • confront self-exempting beliefs
  • are presented in a way that minimises the inevitable process by which repeated exposure gradually diminishes effect.

Health warnings need to

  • cover a broad range of health effects
  • emphasise morbidity as well as mortality
  • cover the same health effect from the points of view of people of different ages and at different stages of smoking uptake and cessation3
  • use language that is clear, strong and direct2
  • explain how the effect occurs in concrete terms
  • paint a picture of what life would feel like should a disease be contracted
  • be frequently rotated and updated to include new images and information that explores different aspects of the particular risk.2

A12.1.4.2 What form should warnings take?

Numerous major reports now have been produced in Canada,4–11 Australia1–17 Europe,18 New Zealand,19,20 the US21 and elsewhere compiling evidence from the rest of the world and conducting studies locally to guide the design of health warnings in each of these jurisdictions. This is a growing field of research, and knowledge is building quickly as to optimal design of warnings.22, 23 See the University of Waterloo's Tobacco Labelling Resource Centre for up-to-date information.ii

Wording matters

Obscure text warnings have little impact. Messages should be short and direct. Messages that depict health risks in a vivid and emotionally arousing manner are likely to be most effective.24

Analysis of warnings on cigarette packaging in the US indicates that comprehending them requires college-level education25, greatly reducing usefulness with young people, less educated people and people with poorer reading skills. Studies by the Centre for Behaviour Research in Cancer in 1992 identified a number of risk-related words that many adolescents poorly understand and that should be avoided in warnings messages.12 Comprehension and impact of warnings is greatly increased if they are expressed in clear, simple language.8,16,17

Size matters

Size can refer to the size of the font of the message or the size of any picture or the amount of space given over to the warning. It is likely that all elements of size are important.

Several studies have established that larger font size is more effective than smaller.12,9,26 Eye tracking studies of youth observing cigarette print advertisements in the United States indicated that adolescents paid scant attention to the very small warnings on advertisements required in the mid-1980s.27

Psychological theory would suggest that smokers would be more likely to recall larger warnings, with bigger warnings associated with greater appreciation and acceptance of risk.2,28 Reviews of the evidence23,29 report that this has been borne out in experimental studies studying various sizes of warnings prior to the introduction of strengthened health warnings. 9,11,12,20,30,31,32 iii Post-implementation research also confirms that increased warning size (at least up to 50% of the front surface, the largest warnings implemented that have been so far studied), increases warning effectiveness.6,13,26

Research undertaken for the Canadian Government9 to guide the design of new warnings to be implemented in 2012 found that health warnings occupying 75% of the pack were more effective than warnings occupying 50% of the pack in conveying information about the health risks of smoking. The study examined a total of 38 effectiveness indicators, grouped into seven sets:

  1. Perceived communication impact (5 indicators)
  2. Personal persuasiveness (1)
  3. Persuasiveness associated with six social styles of smokers (6)
  4. Smoker image (12)
  5. Product image (9)
  6. Emotional impact (4)
  7. Packaging attractiveness (1)

Two sets of indicators were less sensitive to warning size increase: smoker image (personality traits) and product image (cigarette attributes). These image indicators required at least option C (90%) in order to generate significant effects, but these effects remained small even with option D (100%) when contrasted with current scenario A (50%). Findings suggest that while increasing the size of warnings on cigarette packages improves communication impact, increased size is not nearly as effective in negatively affecting the image of smokers or perception of cigarette product attributes.

Graphic elements matter

The importance of font size, headings and layout in aiding consumer comprehension for consumer medicines information is well understood.1

At least two studies have shown that smokers prefer health warnings to appear in a boxed section.19,20 Research on chemical products indicates that textural warning labels with coloured background were perceived to have more impact than those in black and white.33 Contrasting colours such as black lettering on a white background are the easiest to read and comprehend on cigarette packets.12,34

The background to text can serve to focus more or less attention on the text compared with the graphic component of health warnings.16,17

Placement matters

Smokers show better recall for warnings that appear on the front, compared with the side of packages.4,12,19,32

Few smokers however have reported citing packages as a source of information where warnings appeared on the side of the pack.35,36

Research on the Australian graphic warnings, which average more than 50% of the two main sides (30% of the front and 90% of the back), indicates them having weaker effects than the Canadian warnings, which have 50% of both sides dedicated to warnings, suggesting that the back of the pack is less effective than the front, presumably because material on the front is noticed more often.37 Borland and Lal found that more than 90% of packs displayed in public venues (mainly café tables) were front up.38 Smokers tend to have the front of the pack facing them rather than the back each time they remove a cigarette for smoking. Experimental work has also shown that the top of the front is likely to have greater impact than the bottom of the front.12

A Philip Morris document also highlights the importance of positioning on the front of packages:

'Government required warnings placed on the largest packaging panel, often called the front and/or back, are the biggest marketing threat to all of us in Asia...'39.

Pictures work best

Health communication theory and practices suggest that health warnings with pictures are more likely to draw attention, result in greater information processing and improve memory for the health message –see references 42 to 50, in the Tobacco Control review.29

As Hammond highlights29

'Experimental research on cigarette warnings has also found that picture-based warnings are more likely to be rated as effective than text-only warnings on a range of outcomes, including as a deterrent for new smokers and as a means to increase cessation among current smokers.' 29 citing 40–45

There is also an increasing body of real-world evidence showing that graphic warnings lead to more frequent and deeper processing of warning information than text-only warnings.37, 46, 47 Smokers place lower value on cigarettes with graphic health warnings than with text-based warnings.48,49 This is supported by some experimental research comparing warnings of the same size and theme but differing in presentation.43,44

Focus group research in Australia indicated that smokers were much less likely to be able to avoid the image than the text-based component of the proposed new health warnings.

A study comparing the reactions of Chinese smokers to pictorial warnings compared with the current text-based warnings indicated that smokers were about four-times more likely to report thinking about quitting when confronted with pictorial warnings than with packs bearing the current warnings, and about four times less likely to offer cigarettes to others as gifts if these were packaged with strong health warnings.50

Following the introduction of pictorial health warnings in Canada, more than 90% of smokers reported noticing the change. Forty-four per cent of smokers said the new warnings increased their motivation to quit. In a study conducted for the government in Canada,51 more than one-third of former smokers indicated that warning labels had influenced their decision to quit. In a survey of Canadian ex-smokers who had quit in the three years up to October 2001, those who had quit after the introduction of the health warnings were 2.8 times more likely to cite the warning labels as an influence on their quitting than those who quit before their introduction.52

In countries with large pictorial warnings such as Australia, Thailand, and Uruguay, more than 85% of smokers cite packages as a source of health information.23

Pictorial warnings may be particularly important in communicating health information to people with impaired literacy.53 It also seems that graphic health warnings have a far greater impact on young people than text-based warnings.54 Studies of early text-based warnings in the US55 and Australia56 indicated limited impact on young people. Studies examining the impact of improved text warnings in the United Kingdom57 found that these did help to communicate the dangers associated with smoking and prompted a small number of smokers to forgo cigarettes and take action to avoid warnings. However the depth of processing was low and the textual warnings do not appear to be achieving their full potential among young smokers. In Canada by contrast, six years after their introduction, more than 90% of Canadian youth agreed that picture warnings on Canadian packages provide them with 'important information about the health effects of smoking' 'are accurate' and 'made smoking seem less attractive'. 7 Graphic warnings in Australia also appear to have had a much more significant impact on young people58–see Section A12.1.5.1.

Only three studies identified in the Hammond review failed to find a stronger impact for graphic compared with textual health warnings on cigarettes. An experimental study among German youth failed to detect any significant difference of graphic over the then current EU text warnings.59 A second study comparing responses among Canadian-born and US-born students to brief portrayals of text versus graphic warnings found that the graphic warnings were more effective only among the Canadian students (who would have been more familiar with this style of warning). The third study failed to detect a difference in speed of response to warnings which, as the authors acknowledge, may in any case not be an appropriate indicator of impact.3

Potential adverse outcomes of graphic health warnings?

Some researchers have expressed concerns about whether graphic health warnings will assist smokers to sustain quit attempts.60 However a study of attitudes of US smokers to current US warnings compared with Canadian-style61 and other graphic health warnings44,43 have shown stronger negative attitudes to the graphic warnings, without signs of defensive reactions. Greater fear and disgust has been associated with greater likelihood of quitting,62,44,43 providing strong support for the proposition that graphic warnings should be introduced in the US.43 Neither does avoiding health warnings predict a lower likelihood of quitting; indeed, there is evidence that it may actually be associated with increased quitting.37, 63

Context of the pack matters

It is now well established that the warnings need to be on a pre-specified background (e.g. white for black text), because otherwise companies can effectively blend the warning into the design of the pack.64 Smokers recall warnings more effectively on mock packets with a plain background than they do on real, highly stylised cigarette packets.31,65,66,67 This strongly suggests that plain packaging would increase the effectiveness of health warnings. Plain packaging is discussed at length in Chapter 11, Section 11.6.3.

i A study of textual warnings in Switzerland3 demonstrated distinct differences in responses in groups of different ages and smoking status depending on the framing of the warning in terms of severity, time horizon and health versus social focus.

iii A series of studies conducted by Environics Research company for the Canadian Cancer Society in June 2006 similarly found that warnings sized at 75% of the front of the pack would be more effective than those sized 50 or 60%


1. Shrank W, Avorn J, Rolon C and Shekelle P. Effect of content and format of prescription drug labels on readability, understanding, and medication use: a systematic review Annals of Pharmacotherapy 2007;41(5):783-801. Available from: http://www.theannals.com/content/41/5/783.short

2. Strahan EJ, White K, Fong GT, Fabrigar LR, Zanna MP and Cameron R. Enhancing the effectiveness of tobacco package warning labels: a social psychological perspective. Tobacco Control 2002;11(3):183–90. Available from: http://tc.bmjjournals.com/cgi/content/abstract/11/3/183

3. Gygax P, Bosson M, Gay C and Ribordy F. Relevance of health warnings on cigarette packs: a psycholinguistic investigation. Health Communication 2010;25(5):397–409. Available from: http://www.ncbi.nlm.nih.gov/pubmed/20677044

4. Environics Research Group Ltd. Health warnings testing: final report. Ottawa: Prepared for Health Canada, 1999. Available from: http://legacy.library.ucsf.edu/tid/nql70g00

5. Environics Research Group Ltd. Testing new health warning messages for cigarette packages: a summary of three phases of focus group research. Ottawa: Final report prepared for Health Canada, 2000. Available from: http://legacy.library.ucsf.edu/tid/irl70g00

6. Environics Research Group Ltd. The health effects of tobacco and health warning messages on cigarette packages: survey of adults and adult smokers: Wave 9 surveys. Ottawa: Health Canada, 2005. Available from: http://www.smoke-free.ca/warnings/WarningsResearch/POR-04-19%20Final%20Report%205552%20Adult%20wave%209.pdf

7. Environics Research Group Ltd. The health effects of tobacco and health warning messages on cigarette packages: survey of youth: wave12 surveys. Ottawa: Health Canada, 2007. Available from: http://www.hc-sc.gc.ca/hc-ps/tobac-tabac/research-recherche/por-rop/label-etiquet-eng.php

8. Createc & Market Studies. Effectiveness of health warning messages on cigarette packages in informing less-literate smokers. Final report. December. Ottawa: Communication Canada, 2003. Available from: http://www.smoke-free.ca/warnings/WarningsResearch/Createc_LiteracyFinal_EN__Dec03.doc

9. Createc. Effects of modified packaging through increasing the size of warnings on cigarette packages: quantitative study of Canadian adult smokers and vulnerable non-smokers. HC POR-07-47. Ottawa: Health Canada, 2008. Available from: http://epe.lac-bac.gc.ca/100/200/301/pwgsc-tpsgc/por-ef/health/2008/254-07a-e/report.pdf

10. Les E´tudes De Marche Createc. Quantitative study of Canadian adult smokers and vulnerable non-smokers: effects of modified packaging through increasing the size of warnings on cigarette packages. Prepared for Health Canada. Ottawa: Health Canada, 2008. Available from: http://epe.lac-bac.gc.ca/100/200/301/pwgsc-tpsgc/por-ef/health/2008/254-07a-e/report.pdf

11. Les E´tudes De Marche Createc. Quantitative study of Canadian youth smokers and vulnerable non-smokers: effects of modified packaging through increasing the size of warnings on cigarette packages. Prepared for Health Canada. Ottawa: Health Canada, 2008. Available from: http://www.tobaccolabels.ca/healt/canada2008w3

12. Centre for Behavioural Research in Cancer. Health warnings and product labelling on tobacco products. Melbourne: Anti-Cancer Council of Victoria, 1992. Available from: http://legacy.library.ucsf.edu/tid/gku34e00

13. Elliott and Shanahan Research. Evaluation of the health warnings and explanatory health messages on tobacco products. Canberra: Tobacco and Alcohol Strategies Section, Department of Health and Aged Care, 2000. Available from: http://www.health.gov.au/internet/main/publishing.nsf/content/4FA9E17EB0A1FB6ECA25776900054914/$File/warneval.pdf

14. Elliott and Shanahan Research. Developmental research for new Australian health warnings on tobacco products stage 2. Canberra: Population Health Division, Department of Health and Ageing, Commonwealth of Australia, 2003. Available from: http://www.health.gov.au/internet/main/publishing.nsf/Content/4FA9E17EB0A1FB6ECA25776900054914/$File/warnres2.pdf

15. Gfk Blue Moon. Market testing of new health warnings and information messages for tobacco product packaging: Phase 1 Side of pack messages. Canberra: Department of Health and Ageing, 2011. Available from: http://www.yourhealth.gov.au/internet/yourhealth/publishing.nsf/Content/mr-plainpack#.T3Ug6dmFQ8m

16. Gfk Blue Moon. Market testing of new health warnings and information messages for tobacco product packaging: Phase 2 Front and back of pack messages. Canberra: Department of Health and Ageing, 2011. Available from: http://www.yourhealth.gov.au/internet/yourhealth/publishing.nsf/Content/mr-plainpack#.T3Ug6dmFQ8m

17. Gfk Blue Moon. Market testing of new health warnings and information messages for tobacco product packaging: Phase 3 Refinement of health warnings. Canberra: Department of Health and Ageing, 2011. Available from: http://www.yourhealth.gov.au/internet/yourhealth/publishing.nsf/Content/mr-plainpack#.T3Ug6dmFQ8m

18. Sambrook Research International. A review of the science base to support the development of health warnings for tobacco packages. A report prepared for European Commission, Directorate General for Health and Consumers. Brussels: European Commission, 2009. Available from: http://ec.europa.eu/health/tobacco/docs/warnings_report_en.pdf

19. AGB Spectrum Research Ltd. Testing the positions of health warnings on cigarette packages. Christchurch: Health Promotion Programme, Department of Health New Zealand, 1987. Available from: http://legacy.library.ucsf.edu/tid/lel70g00/pdf

20. BRC Marketing & Social Research. Smoking health warnings stage 2: optimising smoking health warnings-text graphics, size, and colour testing. Prepared for the New Zealand Ministry of Health. Wellington: National Drug Policy New Zealand 2004. Available from: http://www.ndp.govt.nz/moh.nsf/indexcm/ndp-publications-smokinghealthwarningsstage2aug2004

21. Hammond D. Tobacco packaging and labelling policies under the US Tobacco Control Act: research needs and priorities. Nicotine & Tobacco Research 2011;[Epub ahead of print] Available from: http://ntr.oxfordjournals.org/content/early/2011/10/24/ntr.ntr182.full

22. Hammond D. Tobacco labelling & packaging toolkit: a guide to FCTC Article 11. Waterloo, ON: Tobacco Labelling Resource Centre, 2009. Available from: http://www.tobaccolabels.ca/tobaccolab/iuatldtook

23. International Tobacco Control Policy Evaluation Project. FCTC Article 11 Tobacco warning labels: evidence and recommendations from the ITC Project. Buffalo, New York: Roswell Park Cancer Institute, 2009. Available from: http://roswelltturc.org/ITCwarningreport.pdf

24. Witte K and Allen M. A meta-analysis of fear appeals: implications for effective public health campaigns. Health Education & Behavior 2000;27(5):591–615. Available from: http://heb.sagepub.com/cgi/reprint/27/5/591

25. Malouff J, Gabrilowitz D and Schutte N. Readability of health warnings on alcohol and tobacco products. American Journal of Public Health 1992;82(3):464. Available from: http://www.ajph.org/cgi/reprint/82/3/464-a

26. Shanahan P and Elliott D. Evaluation of the Effectiveness of the Graphic Health Warnings on Tobacco Product Packaging 2008. Canberra: Department of Health and Ageing, 2009. Available from: http://www.health.gov.au/internet/main/publishing.nsf/Content/F22B9115FD392DA5CA257588007DA955/$File/hw-eval-full-report.pdf

27. Fischer P, Richards E and Krugman D. Recall and eye tracking study of adolescents viewing tobacco advertisements. Journal of American Medical Association 1989;261(1):84-9. Available from: http://www.ncbi.nlm.nih.gov/pubmed/2909000

28. Linthwaite P. Health warnings. Health Education Journal 1985;11:218-19.

29. Hammond D. Health warning messages on tobacco products: a review. Tobacco Control 2011;on line first Available from: http://tobaccocontrol.bmj.com/content/early/2011/05/23/tc.2010.037630.abstract

30. Environics Research Group. Canadian adult and youth opinions on the sizing of health warning messages. Ottawa: Environics Research Group Limited, 1999. Available from: http://dsppsd.pwgsc.gc.ca/Collection/H49-134-1999E.pdf

31. Rootman I and Flay B. A study on youth smoking: plain packaging, health warnings, event marketing and price reductions. Toronto: University of Toronto, University of Illinois at Chicago, York University, Ontario, Tobacco Research Unit, Addiction Research Foundation, 1995. Available from: http://www.smoke-free.ca/plain-packaging/documents/1995/Rootman-youthsmoking.pdf

32. Cragg, Ross and Dawson Ltd. Health warnings on cigarette and tobacco packs: report on research to inform European standardisation. London: Health Education Authority, 1990. Available from: http://legacy.library.ucsf.edu/tid/tdl70g00

33. Braun CC, Kline P and Silver N. The influence of color on waning label perceptions. International Journal of Industrial Ergonomics 1995;15(3):179-187. Available from: http://www.sciencedirect.com/science/article/pii/0169814194000363

34. Nilsson T. Legibility of tobacco health messages with respect to distance. A report to the Tobacco Products Division of the Health Protection Branch of Health and Welfare Canada. Ottawa: 1991. Available from: http://dsp-psd.pwgsc.gc.ca/Collection/H49-132-1999E.pdf

35. Hammond D, Fong GT, McNeill A, Borland R and Cummings KM. Effectiveness of cigarette warning labels in informing smokers about the risks of smoking: findings from the International Tobacco Control (ITC) Four Country Survey. Tobacco Control 2006;15(suppl. 3):iii19–25. Available from: http://tc.bmjjournals.com/cgi/content/abstract/15/suppl_3/iii19

36. Crawford M, Balch G, Mermelstein R and Group TTCNW. Responses to tobacco control policies among youth Tobacco Control 2002;11:14-19. Available from: http://tobaccocontrol.bmj.com/content/11/1/14.abstract?sid=042b9b6f-2a18-4d9e-9355-8a43ee0ffd5e

37. Borland R, Wilson N, Fong GT, Hammond D, Cummings KM, Yong HH, et al. Impact of graphic and text warnings on cigarette packs: findings from four countries over five years. Tobacco Control 2009;18(5):358-64. Available from: http://tobaccocontrol.bmj.com/cgi/content/abstract/18/5/358

38. Borland R and Lal A. Position of cigarette packs. Unpublished report. Melbourne: VicHealth Centre for Tobacco Control, 2004.

39. Hulit M. Marketing issues corporate affairs conference, May 27 Manila. Bates no. 2504015017/5042. Philip Morris, 1994. Available from: http://legacy.library.ucsf.edu/tid/jga42e00

40. Liefeld J. The relative importance of the size, content and pictures on cigarette package warning message. Ottawa: Department of Consumer Studies, University of Guelph, 1999. Available from: http://legacy.library.ucsf.edu/tid/sql70g00

41. O'Hegarty M, Pedersen L, Nelson D, Mowery P, Gable J and Wortley M. Reactions of young adult smokers to warning labels on cigarette packages. American Journal of Preventative Medicine 2006;30(6):467–73. Available from: http://www.ncbi.nlm.nih.gov/pubmed/16704939

42. Vardavas C, Connolly G, Karamanolis K and Kafatos A. Adolescents perceived effectiveness of the proposed European graphic tobacco warning labels. European Journal of Public Health 2009;19(2):212–7. Available from: http://eurpub.oxfordjournals.org/cgi/content/full/19/2/212

43. Kees J, Burton S, Andrews J and Kozup J. Understanding how graphic pictorial warnings work on cigarette packaging. Journal of Public Policy & Marketing 2010;29(2):265-76. Available from: http://www85.homepage.villanova.edu/jeremy.kees/publications/Kees_JPPM2010_CWL.pdf

44. Kees J, Burton S and Andrews J. Tests of graphic visuals and cigarette package warning combinations: implications for the Framework Convention on Tobacco Control. Journal of Public Policy Marketing 2006;25:212-3. Available from: http://www.who.int/fctc/guidelines/ArtElevenKeesEighteen.pdf

45. Sabbane LI, Lowrey TM and Chebat J-C. The effectiveness of cigarette warning label threats on nonsmoking adolescents. Journal of Consumer Affairs 2009;43(2):332–45. Available from: http://onlinelibrary.wiley.com/doi/10.1111/j.1745-6606.2009.01142.x/abstract

46. Borland R, Yong H, Wilson N, Fong G, Hammond D, Cummings K, et al. How reactions to cigarette packet health warnings influence quitting: findings from the ITC Four-Country survey. Addiction 2009;104(4):669-75. Available from: http://www.ncbi.nlm.nih.gov/pubmed/19215595

47. Thrasher JF and Villalobos Vea. Assessing the impact of cigarette package health warning labels: a cross-country comparison in Brazil, Uruguay and Mexico. Salud Pública de México 2010;52(suppl. 2):ii206-15. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21243191

48. Thrasher J, Rousu M, Anaya-Ocampo R, Reynales-Shigematsu L, Arillo-Santillán E and Hernández-Avila M. Estimating the impact of different cigarette package warning label policies: the auction method. Addictictive Behaviour 2007;32(12):2916-25. Available from: http://www.ncbi.nlm.nih.gov/pubmed/17630221

49. Thrasher J, Hammond D, Fong G and Arillo-Santillán E. Smokers' reactions to cigarette package warnings with graphic imagery and with only text: a comparison between Mexico and Canada. Salud pública de México 2007;49(suppl. 2):S233-40.

50. Qin Y, Wu M, Pan X, Xiang Q, Huang J, Gu Z, et al. Reactions of Chinese adults to warning labels on cigarette packages: a survey in Jiangsu Province. BMC Public Health 2011;11:133. Available from: http://www.biomedcentral.com/content/pdf/1471-2458-11-133.pdf

51. Environics Research Group Ltd. Evaluation of new warnings on cigarette packages. Ottawa: Canadian Cancer Society, 2002. Available from: http://legacy.library.ucsf.edu/tid/bkm70g00

52. Hammond D, McDonald PW, Fong G, Brown KS and Cameron R. The impact of cigarette warning labels and smoke-free bylaws on smoking cessation-evidence from former smokers. Canadian Journal of Public Health 2004;95(3):201–4. Available from: http://www.ginfo.pl/objects/15191132,The,impact,of,cigarette,warning,labels,and,smoke,free,bylaws,on,smoking,cessation,,evidence,from,former,smokers,.html

53. Millar W. Reaching smokers with lower levels of educational attainment. Health Reports 1996;8(2):11–9. Available from: http://www.statcan.gc.ca/bsolc/olc-cel/olc-cel?catno=11-008-X19970013034&lang=eng

54. Peterson E, Thomsen S, Lindsay G and John K. Adolescents' attention to traditional and graphic tobacco warning labels: an eye-tracking approach. Journal of Drug Education 2010;40(3):227–44. Available from: http://www.ncbi.nlm.nih.gov/pubmed/21313984

55. Robinson T and Killen J. Do cigarette warning labels reduce smoking? Paradoxical effects among adolescents. Archives of Pediatrics & Adolescent Medicine 1997;151(3):267-72. Available from: http://www.ncbi.nlm.nih.gov/pubmed/9080935

56. Ho R. Cigarette advertising and cigarette health warnings: what role do adolescents' motives for smoking play in their assessment? Australian Psychologist 1994;29(1):49-56. Available from: http://onlinelibrary.wiley.com/doi/10.1080/00050069408257321/abstract

57. Moodie C, Mackintosh A and Hammond D. Adolescents' response to text-only tobacco health warnings: results from the 2008 UK Youth Tobacco Policy Survey. European Journal of Public Health 2009;20(4):463-9. Available from: http://eurpub.oxfordjournals.org/cgi/content/full/ckp199v1

58. White V, Webster B and Wakefield M. Do graphic health warning labels have an impact on adolescents' smoking-related beliefs and behaviours? Addiction 2008;103(9):1562–71. Available from: http://www.ncbi.nlm.nih.gov/pubmed/18783508

59. Petersen L and Lieder F. Die Effektivita¨t von schriftlichen und graphischen Warnhinweisen auf Zigarettenschachteln: eine U¨berpru¨fung des revidierten Modells der Schutzmotivation. Zeitschrift fu¨r Sozialpsychologie 2006;37(245-58)

60. Schneider S, Gadinger M and Fischer A. Does the effect go up in smoke? A randomized controlled trial of pictorial warnings on cigarette packaging. Patient Education and Counseling 2011;[Epub ahead of print] Available from: http://www.ncbi.nlm.nih.gov/pubmed/21482060

61. Peters E, Romer D, Slovic P, Jamieson K, Wharfield L, Mertz C, et al. The impact and acceptability of Canadian-style cigarette warning labels among US smokers and nonsmokers. Nicotine & Tobacco Research 2007;9(4):473–81. Available from: http://www.informaworld.com/smpp/content~db=all?content=10.1080/14622200701239639

62. Hammond D, Fong G, McDonald P, Brown K and Cameron R. Graphic Canadian cigarette warning labels and adverse outcomes: evidence from Canadian smokers. American Journal of Public Health 2004;94(8):1442–5. Available from: http://www.ajph.org/cgi/content/full/94/8/1442

63. Borland R. Tobacco health warnings and smoking-related cognitions and behaviours. Addiction 1997;92(11):1427–35. Available from: http://www3.interscience.wiley.com/journal/120194864/abstract

64. Borland R and Hill D. The path to Australia's tobacco health warnings. Addiction 1997;92(9):1151–7. Available from: http://www3.interscience.wiley.com/journal/119158300/abstract

65. Centre for Health Promotion. Effects of plain packaging on the image of tobacco products among youth. Toronto: University of Toronto, 1993. Available from: http://tobaccodocuments.org/pm/2504106502-6535.html

66. Goldberg M, Liefeld J, Madil J and Vredenburg H. The effect of plain packaging on response to health warnings. American Journal of Public Health 1999;89(9):1434–5. Available from: http://www.ajph.org/cgi/reprint/89/9/1434

67. Beede P and Lawson R. The effect of plain packages on the perception of cigarette health warnings. Public Health 1992;106(4):315–22. Available from: www.ncbi.nlm.nih.gov/pubmed/1529094