Tobacco use has been identified by the World Health Organization as the leading cause of death and disability in the world.1
To date, more than 24 different smoking‐related diseases have been identified, including cardiovascular disease, respiratory disease, and 10 different forms of cancer.2
The extent to which smokers understand the magnitude of these health risks has a strong influence on their smoking behaviour.3,4,5
Smokers who perceive greater health risk from smoking are more likely to intend to quit and to quit smoking successfully.6,7
The health risks of smoking are also the most common motivation to quit cited by current and former smokers, as well as the best predictor of long‐term abstinence among reasons for quitting.8,9,10
At present, most smokers concede that tobacco use is a health risk; however, important gaps remain in their understanding of these risks.11,12,13,14
Many smokers are unable to recall specific health effects and most tend to underestimate the scope of these effects.11,15,16,17,18,19
Even in countries such as Canada, with among the most progressive tobacco control policies in the world, a significant proportion of smokers continue to underestimate the most serious risks of smoking, including heart disease, stroke, and respiratory disease, as well as the risks of environmental tobacco smoke.11,20
In addition to the fact that smokers are not fully informed, there are biases in how smokers perceive these risks. In a review of the research literature, Weinstein21
found that, although most smokers acknowledge the risk of smoking, they tend to “minimize that risk and show a clear tendency to believe that the risk applies more to other smokers than to themselves” (page 139). Considerably less is known about smokers' knowledge of the constituents of tobacco smoke, including well‐known toxicants such as carbon monoxide and cyanide. What little evidence exists suggests a very low level of awareness,22,23
although the impact of this knowledge remains largely unexplored.
Communicating the health effects of smoking remains a primary goal of tobacco control policy.24
Indeed, the World Health Organization's Framework Convention on Tobacco Control (FCTC) states as its first guiding principle that: ”Every person should be informed of the health consequences, addictive nature and mortal threat posed by tobacco consumption and exposure to tobacco smoke” (Article 4.1). Cigarette warning labels are among the most widespread policy initiatives implemented to educate smokers. Recent research indicates that graphic warning labels on cigarette packages can increase cessation behaviour among smokers25,26,27
; however, despite their prominence among tobacco control policies, only a handful of studies have evaluated the impact of different product warning policies on consumer knowledge about tobacco risks.
A study commissioned by Imperial Tobacco reported an increase in the proportion of smokers who agreed that smoking is dangerous following the introduction of Canada's first warning labels in 1972.28
Cross‐sectional surveys conducted in Canada during the 1990s found that the majority of smokers reported that package warning labels are an important source of health information and have increased their awareness of the risks of smoking.11,29
In Australia, Borland30
found that, relative to non‐smokers, smokers demonstrated an increase in their knowledge of the main constituents of tobacco smoke and identified significantly more disease groups following the introduction of new Australian warning labels in 1995. However, considering the importance of health warnings among tobacco control policies, there is a need for additional research. In particular, there is a need for research that can help policymakers to choose the size and general strength of health warnings from within the general recommendations outlined in the FCTC.
At present, cigarette packages in virtually every country carry warning labels,31
yet the size, number, and the way the health information is presented differs notably between countries. Labelling policies range from vague statements of risk (for example, “Smoking can be harmful to your health”), to graphic pictorial depictions of disease. Because of the variation between countries in package warning labels, an opportunity now exists to explore the impact of different warning policies on consumer knowledge. The International Tobacco Control Four Country Survey (ITC‐4) is a cohort survey of adult smokers conducted in four countries—the United States (USA), the United Kingdom (UK), Canada (CAN), and Australia (AUS)—that was designed to examine the impact of national‐level tobacco control policies, including warning labels. Figure 1 depicts health warnings in the four countries participating in the ITC‐4 Survey as of Wave 1 of the survey, conducted in 2002.*
Figure 1Cigarette package warning labels of the four countries (Canada, Australia, United Kingdom, United States) participating in the International Tobacco Four Country Survey (as of 2002).
The aim of the current study was to use nationally representative samples of adult smokers from the USA, UK, CAN, and AUS to: (1) examine smokers' knowledge that smoking causes heart disease, stroke, impotence, and lung cancer; (2) to assess smokers' knowledge of the constituents of tobacco smoke, including carbon monoxide, cyanide, and arsenic; and (3) to examine the relationship between health knowledge in each country and that country's tobacco labelling policy.