Smoking and snus use in Norway
- About 30 per cent of adults use tobacco, either as cigarettes or snus.
- Smoking is as common among women as men.
- Since 2000 there has been an increase in snus use. In the 16-24 year age group, 1 in 4 used snus in 2016, either daily or occasionally.
- There are clear socioeconomic differences. For smoking and snus, tobacco use is lowest in the group with a longer education.
- There has been a major decline in smoking among pregnant women. We do not have information about their use of snus.
- Annually, 6000 people die as a result of smoking.
About tobacco and nicotine
Tobacco can be chewed, smoked or placed under the lip in small, moist clumps. Tobacco leaves contain nicotine, and all types of tobacco use cause the user to ingest nicotine. This is a highly addictive substance and users can become addicted after short-term use. In addition, when tobacco is smoked, other harmful substances are released.
Tobacco use is of major importance to public health (NIPH, 2017a).
Previously, it was not allowed to sell e-cigarettes with nicotine in Norway. In December 2016, the Storting (Norwegian parliament) decided to abolish this prohibition. From July 2017, vaping of e-cigarettes, both with and without nicotine-containing liquids, are included in the Tobacco Control Act so that in places where smoking is forbidden, vaping will also be forbidden. The main reason for the inclusion of e-cigarettes is that exposure to their vapour can have a health risk for vulnerable groups (Norwegian Directorate of Health 2018).
E-cigarettes will not be discussed further in this chapter.
Status of tobacco use in Norway
Data from annual surveys in Statistics Norway are the main basis for estimating how many people smoke and use snus in Norway. The questions about smoking habits are commissioned by the Norwegian Institute of Public Health. From a country-representative annual sample of 8000 aged 16-74 years, 55-65 per cent agree to participate. This figure has been quite stable and data quality is generally good. Data about pregnant women are available from the Medical Birth Registry, see the section on smoking among pregnant women.
Smoking and snus use
Historically, smokers have made up the largest group of tobacco users, while the group that uses snus has been much smaller. However, the difference between the groups has decreased in recent years and by 2017 the groups were of similar size.
Daily smoking is equally common among women and men when we see all age groups combined.
By 2017, there were 29 per cent in the age group 16-74 years who smoked or used snus. Of these, two out of three used tobacco daily. (Statistics Norway, 2017a).
Snus is the most common tobacco product used by young people in the 16-24 year age group. Also among men in the 25-44 year age group, snus use is significantly more common than smoking, see figure 1a and 1b.
See the additional figure showing different groups of tobacco users.
Figure 1a: Daily smoking (røyking) and snus use among men of different age groups 2017. Vertical axis shows percentage. Source: Statistics Norway. Diagram: norgeshelsa.no.
Figure 1b: Daily smoking (røyking) and snus use among women of different age groups 2017. Vertical axis shows percentage. Source: Statistics Norway. Diagram: norgeshelsa.no
- Figure 1c shows tobacco use in all age groups 16-74 years, with dual users shown as own group and daily and occasionally users combined, 2013-2015. Source: Norhealth / Statistics Norway.
- Figure 1d shows tobacco use among young people aged 16-24, with dual users shown as own groups and daily and occasionally users combined, 2013-2015. Source: Norhealth / Statistics Norway.
In the period from 2005 to 2014, each year between 4 500 and 10 000 young people aged 16-24 became daily smokers (Vedøy, 2015).
For Norwegian women, the average age of smoking debut has fallen from 20 years in 1980 to about 18 years by 2015. Men also began to smoke at about 18 years in 2015.
The debut age for using snus was 24 years for both men and women in 2015 (Vedøy, 2015).
7 out of 10 are tobacco-free
In the whole 16-74 year age group, approximately 70 per cent are tobacco-free. There are more tobacco-free women than men, and most are in the over 25 age group. See additional figures 1c and 1d.
Every year from 2005 to 2014, between 19,000 and 38,000 adults aged 25-69 years quit daily smoking (Vedøy, 2015).
Smoking: The proportion of daily smokers is highest in the counties of Østfold, Finnmark and Telemark, by 18 per cent (NIPH, 2018), see figure 2a. Figures are from 2013-2017 and apply for the 16-74 year age group.
The three counties of Oslo, Akershus, and Sør-Trøndelag had the lowest proportion of daily smokers by 9-11 per cent, see figure 2a.
In all counties there are most smokers in the 45-64 year age group. This applies to the whole country and for most counties.
Figure 2a. The percentage of daily smokers by county, as a percentage. Age group 16-74 years, 2012-2016.
Figure 2b. Men who smoke daily in the 16-74 year age group, 2012-2016. Source: Norhealth / Statistics Norway.
Figure 2c. Women who smoke daily in the 16-74 year age group, 2012-2016. Source: Norhealth / Statistics Norway.
Snus: The proportion who use snus daily is highest in Finnmark (13 per cent) and Trøndelag (12 per cent) and lowest in the Agder counties with 7 per cent, see Figure 3a (NIPH, 2018). Figures are from 2013-2017, for the 16-74 year age groups.
Figure 3a. The proportion that uses snus daily by county, age group 16-74 years, figures from 2012-2016. Source: Norhealth / Statistics Norway.
In all counties, there are most snus users in the youngest age groups, see additional figures 3b and c.
Figure 3b. The proportion of men who use snus daily in the county, age group 16-44 years. Data are missing for some counties. Source: Norhealth / Statistics Norway.
Figure 3c.The proportion of women who use snus daily in the county, age group 16-44 years. Data are missing for some counties. Source: Norhealth / Statistics Norway.
Smoking in the Sami population
The SAMINOR study shows that there is generally a slight difference between Sami and non-Sami regarding the proportion of daily smokers, although the proportion is higher among Sami in some age groups (Eliassen, 2015; Eriksen, 2015; Nystad, 2010), unpublished data from SAMINOR 2 and among Sami men on the mainland (Broderstad, 2007).
Smoking among immigrants
In 2016, a new living conditions survey was conducted among immigrants (Statistics Norway, 2017). In all immigrant groups, the proportion of men who smoked daily was 26 per cent and 10 per cent for women. In addition, just under 10 per cent smoked occasionally, this was true for both sexes.
Since the previous living conditions survey among immigrants 10 years ago, there has been a stronger decline in the proportion of smokers in the total population than in the immigrant population. Even if there is also a decline in immigrant smokers, immigrants from new country groups have helped to keep the smokers' share of immigrants at a high level.
The highest percentage of daily smokers is found among men from Poland and Turkey, 35-36 per cent. The lowest proportion is found among men from Sri Lanka, Eritrea and Afghanistan (7-9 per cent).
Among women, the proportion of daily smokers was the highest among immigrants from Poland, Turkey and Bosnia-Herzegovina (about one in five). Almost no women from Afghanistan, Pakistan, Sri Lanka, Eritrea and Somalia smoke.
Trends over time
Smoking 1910 - 2000
Around 1910, almost 30 per cent of Norwegian men smoked but very few women.
1950s. Smoking among men increased until the mid-1950s. At the highest levels, about 70 per cent of men smoked. Among women, smoking increased much slower. By the mid-1950s, between 25 and 30 per cent smoked.
1960-2000. From the mid-1950s, a steep decline in smoking among men began, while the increase continued for women (Engeland, 1993). The average rates show that smoking among women remained unchanged from 1970 to the end of the 1990s, see Figure 4.
The apparent stability among women conceals differences between the age groups. There were very few smokers among elderly women and relatively more among the younger women. In the first half of the 1970s about 40 per cent of the youngest women smoked.
By the end of the 1990s, the proportion of smokers was equal among women and men. The figures began to decline for both sexes in line with various systematic measures, see Figure 4.
Figure 4: Developments in smoking among women and men (16-74 years) and the date of systematic measures against tobacco in the period 1973-2016. Source: Norhealth / Statistics Norway.
Since 2000: From the turn of the century we have seen a decline in smoking for both sexes, see figure 5a. At the same time, the use of snus has increased, especially among younger people, see Figures 5b and 7.
Figure 5a: Daily smokers in age groups between 16 and 74 years, 2005-2016. Both sexes combined. Source: Norhealth / Statistics Norway.
Figure 5b: Daily smokers in age groups between 16 and 74 years, 2008 - 2016. Both sexes combined. Source: Norhealth / Statistics Norway.
Snus has increased since 2000
In 2014, the proportion of men who smoked daily was as high as the proportion who used snus daily, when we see all age groups combined, see figure 6. Since then, the proportion of men who use snus has increased and is now greater than the proportion who smoke daily.
Figure 6: The proportion that smokes and uses snus daily, all age groups combined. Source: Norhealth / Statistics Norway.
Among the youngest (16-24 years old) snus is the dominant tobacco form for both women and men see Figure 7 (Statistics Norway, 2017). Among young men in the 25-44 age group, snus use is much more common than smoking for men, and in 2017 it was more common for women to use snus daily than to smoke daily (9 and 8 per cent, respectively).
Figure 7: Daily smoking and snus use 2000-2016 among men and women 16-24 years, 2000-2016. Source: Norhealth / Statistics Norway.
The occasional use of cigarettes has been fairly stable at around 10 per cent for men and somewhat lower for women of all age groups combined, despite the fact that daily smoking has declined. A contributory reason for this may be that occasional smoking is often associated with dual use, see fact box.
What is a dual user?
Dual users both smoke and use snus. It is most common to use snus daily and smoke occasionally.
In the total 16-74 year age group, 6 per cent of men and 2 per cent of women are dual users.
Among the youngest (16-24 years), 13 per cent of men and 7 per cent of women are dual users.
The group of occasional smokers includes both solely "occasional smokers" and dual users and counts for 17 per cent of young men and 11 per cent of young women in the 16-24 year age group.
The decline in the proportion of smokers in the Norwegian population has since year 2000 occurred in parallel with an increase in the proportion that use snus, see figure 8. Some of the increase is due to snus being used as a means to quit smoking (Lund, 2017; Lund, 2013).
Adults who combine cigarettes with snus smoke fewer cigarettes per day / week than those who only smoke. Plans for a non-smoking future are often more frequent among dual users than among those who only smoke (Lund, 2017; Lund, 2013). However, the risk of continuing with dual use is still high, and a high proportion of those who quit smoking seem to continue with snus (DiFranza, 2012; Lund, 2010). See the section on nicotine addiction.
Snus use among young people has been a trend since the turn of the millennium, with one group beginning with snus without taking the smoking route first (Wiium, 2009).
Social differences in smoking and snus use
Tobacco habits vary among different education and income groups:
- 7 per cent of those with university or college education smoke daily.
- 26 per cent of those with basic school education smoke daily.
Around 1950 or earlier, the situation was reversed. There were most smokers among doctors and other highly educated people. When the harmful effects became known, this group quit first (Lund, 1996). As a result, differences in smoking behaviour between the different education groups widened.
Figure 8 shows that there has been a decrease in daily smoking in all three education groups in the last 15-20 years, but differences are still large.
Figure 8: Daily smoking by education in the period 2005-2017. Source: Norhealth / Statistics Norway.
Occasional smokers have a longer education than daily smokers. Over half of those who were occasional smokers in their early twenties were able to quit before they were 30-years-old (Kvaavik, 2014).
At the end of the 1990s, snus use was lower in the lower education group than in the other education groups, but the differences levelled out and then increased in parallel for some years. In recent years, those with a higher education seems to use less snus than those with low education, see Figure 9.
Figure 9: Daily use of snus among adults (25-74 years) by education level in the period 2008-2017. Source: Norhealth / Statistics Norway.
The social differences in tobacco use can already be seen in high school, see Figures 10 and 11, which show smoking and snus use among students with different socioeconomic status. The figures are from the Ungdata-studies in all counties in the period 2014-2016.
In the figures, a socioeconomic status is used, similar to the family affluence scale used in the international HBSC study in which Norway participates. Socioeconomic status is defined by parents and their family’s combined resources. More information is available in the report "Social Differences in Young People's Life" (NOVA, 2016).
- Figure 10: Smoking daily or occasionally (once a week or less) in 8-10th grade by socioeconomic status 2014 - 2016. Percentage. Source: NOVA 2017.
- Figure 11: Use of snus daily or occasionally (once a week or less) in 8-10th grade by socioeconomic status 2014 - 2016. Percentage. Source: NOVA 2017.
Pregnancy: Still fewer smokers
There has been a strong decline in the percentage of pregnant women who smoke, this has more than halved from 2005 to 2015, see Figure 12.
In 2005, almost every sixth (16 per cent) pregnant women smoked at the beginning of pregnancy and almost every tenth (9 per cent) at the end of pregnancy. By 2015, the number decreased to less than every 20th woman (6 and 3 per cent) (NIPH, 2017c).
Figure 12 shows the development of daily smoking among pregnant women by the end of pregnancy. By 2015 there were still the most daily smokers among the youngest, but there is little difference between the age groups. A total of 3 per cent smoked at the end of pregnancy in 2015.
Figure 12: The proportion of daily smokers at the end of pregnancy. Different age groups of pregnant women percentages. Data source: Medical Birth Registry Diagram: Norgeshelsa.no
We still do not have national statistics for snus use in pregnancy. A change of regulation in 2017 will open for data about snus use to be included in the annual statistics of the Medical Birth Registry (NIPH, 2016).
For several years, Sørlandet Hospital has registered snus use for pregnant women. In the period 2012-2014, 2.4 per cent used snus at the start and 1.7 per cent at the end of pregnancy. The proportion was higher among the youngest women (Rygh, 2016).
Social differences in smoking among pregnant women
Smoking in pregnancy is most widespread (Cupul-Uicab, 2012)
- Among younger pregnant women
- Among pregnant women with low education
- Among first-time mothers
- Among pregnant women with unplanned pregnancies
- Among the daughters of parents who smoke
The large decline in smoking among pregnant applies to all educational groups, and there has been an average decline since 1999. Nevertheless, there is a much higher proportion among those with low education who smoke at the beginning of pregnancy (21 per cent) than among those with a high education (2 per cent) (Grotvedt, 2017).
Social differences for smoking in pregnancy help to maintain social differences in health, since smoking seems to negatively impact the health of the mother, the foetus and the child. See section on tobacco and impact on the foetus below.
Figure 13 shows daily smoking in the Nordic countries and the EU. There are no big differences between Norway, Iceland and Sweden. In the Nordic countries, Denmark and Finland have the most daily smokers.
For all EU countries, the proportion of daily smokers among men is 27 per cent.
Figure 13 shows that Finland has had the weakest decline in smoking in the last decade but differences in the Nordic countries for percentage of daily smokers is now less than before (Directorate of Health, 2013). Iceland has had the greatest improvement among the Nordic countries.
Figure 13: Daily smoking in the Nordic countries 2000-2015. Source: WHO, HFA 2017.
Global figures: In the period 1980-2012, the proportion of daily smokers in the world fell from 41 to 31 per cent for men and from 11 to 6 per cent for women (age standardised). However, the population increase led to the number of smokers continuing to increase. In 1980 there were 721 million daily smokers in the world and in 2012 there were 967 million (Ng, 2014).
Health risks and disease as a consequence of tobacco use
Several diseases are associated with smoking (National Centre for Chronic Disease Prevention Health Promotion Office on Smoking Health, 2014), the most important are:
- cardiovascular disease
- chronic respiratory diseases, including COPD
Smoking and snus are linked to (NIPH, 2014; SCENIHR, 2008):
- birth defects and stillbirth
- nicotine dependency
- damage to gums and teeth
These points are discussed later in the text.
Every fifth death before 70 years due to smoking
- Half of all smokers die earlier than they would as non-smokers (Peto, 1994). In Norway it is estimated that over 6,000 died of smoking in 2015.
- Those who have smoked cigarettes since early in life, but quit when they were 30-50 years old, gain between 6 and 10 years of life compared to those who continued to smoke (Jha, 2014).
- Smoking is the biggest risk factor for lost life years in populations. 20 per cent of deaths in the under 70 age group can be attributed to smoking, see figure 26 in the disease burden report (NIPH, 2017a). Nearly half of heavy smokers die before they reach 70 years.
- Cardiovascular disease used to be the most frequent cause of death among smokers (Vollset, 2006). Today, smoking is a risk factor for cancer deaths, especially lung cancer, but also leads to mortality through cardiovascular disease, COPD and lower respiratory tract infections. In addition, smoking leads to impaired health as a consequence of these diseases (NIPH, 2017a).
Smoking and cardiovascular disease
Mortality from cardiovascular disease has fallen significantly for a long time. Men have had a steeper decline in mortality in cardiovascular disease than women. This may be due to men having a faster decline in smoking than women until the late 1990s.
The Tromsø study confirms this picture. The decline in smoking can account for 13 per cent of the decline in coronary heart disease from 1994 to 2008, while positive trends in cholesterol, blood pressure and physical activity have also been important (Mannsverk, 2016).
See Fact Box and Chapter Cardiovascular disease in Norway.
Tobacco and cardiovascular disease
Smoking increases the risk of cardiovascular disease. Quitting smoking quickly reduces the risk and after five years the risk of heart attack appears to be at the level of non-smokers (Bakhru, 2005; Tverdal, 1993).
Snus use also impacts the cardiovascular system because snus affects blood pressure and heart rate. There is no evidence that snus gives an increased risk of cardiovascular disease but may cause greater mortality for those who already suffer from heart disease (SCENIHR, 2008, Arefalk et al 2014).
Smoking and lung cancer
The number of new lung cancer cases per year has been the greatest among men for many years, and this is still the case. However, there is a large increase among women and the gender gap is shrinking, see Figure 16 (Cancer Registry, 2016a).
Figure 14. Average annual number of new lung cancer cases over five-year periods. Source Cancer Registry.
The number of new cases of lung cancer has never been as high as in 2016 (Cancer Registry, 2016b), when 3080 people developed lung cancer in Norway, 1465 women and 1615 men.
It takes decades to develop cancer as a consequence of smoking and even if there has been a decrease in the percentage of women who smoke, it will also take a long time before the figures for morbidity and mortality decline for women.
If we assume a similar change in smoking habits will continue in the years to come, we can expect that in the period 2025-2029 there will be an average of 3700 new cases of lung cancer annually. Half of the patients will be under 75 years at the time of diagnosis (Cancer Registry, 2016a).
Other cancerous diseases are also associated with tobacco use, see fact box.
Tobacco and cancer
Smoking: Many lung cancer cases in Norway could be prevented if nobody smoked. It can take 20-40 years to develop lung cancer from the age when smoking starts.
The risk is greatly reduced after quitting, particularly at a young age. The risk of lung cancer begins to decrease within one to four years after quitting. More than ten years after quitting, the risk of developing lung cancer is higher than for those who have never smoked, but significantly lower than for smokers (IARC, 2004; Peto, 2000).
Passive smoking, workplace pollution, radon gas in the residence, and outdoor air pollution can also contribute to the increased risk of lung cancer.
Smoking also increases the risk of cancer in a number of other organs such as the nasal cavity and sinuses, mouth, throat, pharynx, oesophagus, stomach, rectum, liver, cervix, ovaries, bladder, kidney, pancreas and bone marrow (leukaemia). The risk of these diseases is reduced after quitting smoking.
Snus use: Currently, we know that smoking gives a much higher risk of cancer than snus. Cancer develops over a long time, and we cannot know how today's snus use will affect how many cancer cases we will have in future. The three types of cancer that can be associated with snus are pancreatic, oesophageal and tongue / mouth, all of which are relatively rare.
Smoking, Chronic Obstructive Pulmonary Disease (COPD) and asthma
Smoking is the most common cause of COPD and explains two out of three cases (HOD, 2006). The risk increases with tobacco consumption and number of smoking years. Compared with non-smokers, smokers have an average 4.2 times more risk and former smokers 3.6 times more risk of developing COPD (HOD, 2006; Hvidsten, 2010).
Asthma may occur as a consequence of smoking, and asthmatics may experience a worsening of the disease by smoking (Piipari, 2004).
- See COPD in the Public Health Report
Tobacco use and damage to the gums and teeth
Smoking and snus use can harm teeth and gums. Minor damage to the gums will resolve when smoking / using snus stops but the gum can retract with loss of tissue support around the teeth. This may cause teeth to loosen and change position (Norwegian Directorate of Health, 2015).
Smoking and snus affect fertility and foetal growth
Fertility: It is well documented that smoking reduces fertility in both men and women (Ye, 2010; Cupul-Uicab, 2011; Baird, 1985; Howe, 1985).
Affects the foetal weight. A few cigarettes per day can cause the risk of growth reduction in the foetus to double, and with larger smoking doses, the risk increases further (see Figure 15).
Reduced foetal growth: Snus also increases the risk of growth reduction and premature birth. The risk increases by 30-40 per cent for those who use snus in pregnancy compared to those who do not use tobacco (Gunnerbeck, 2014; Baba, 2014; Wikstrom, 2011).
Figure 15. The relationship between daily smoking and risk (OR) for reduced foetal growth 1999–2013. Source: Medical Birth Registry.
Increased risk of stillbirth is perhaps the most serious unwanted pregnancy outcome for women who smoke or use snus. The absolute risk is low, according to numbers based on 850 000 births in the Swedish Medical Birth Registry. The risk of having a stillborn child was 0.25 per cent among non-tobacco users, 0.40 per cent in snus users and 0.46 per cent among smokers (Baba, 2014).
Increased risk of cot death: When the mother smokes both during and after pregnancy, it increases the risk of cot death (Zhang, 2013). The risk depends on how often she smokes.
Passive smoking in infants. The child ingests more nicotine from passive smoking than through breast milk, even if only the mother, and not the father, smokes (Fleming, 2007; Bajanowski, 2008).
Affects the health of the child in adulthood. Smoking during pregnancy has negative effects on the health of the child long into adulthood. Data from the Norwegian Mother and Child Cohort Study show that a woman who was exposed to smoking as a foetus has an increased risk of obesity, high blood pressure and diabetes in adulthood. The study also shows that they have an increased risk of experiencing reduced fertility, developing pre-eclampsia in their own pregnancy and are at greater risk of stillbirth of their own child (Cupul-Uicab, 2012; Cupul-Uicab, 2011).
Nicotine is highly addictive. Three out of four daily smokers have tried to quit at one time. More than half of the former daily smokers managed to quit either on their first or second attempts, while the remainder tried several times before they succeeded (Directorate of Health, 2013).
Some studies indicate that the use of snus and dual use causes more dependence than smoking alone (Rydell, 2016; Post, 2010). Nevertheless, there is also the opposite finding; that it was harder to quit cigarettes than snus (Fagerstrom, 2012). It is possible that future studies can give a good answer to this as methods for measuring dependence will also be better adapted to the use of snus.
One Norwegian study suggests that the increase in snus use has contributed to a reduction in cigarette use through three mechanisms: firstly, snus was used as an aid to quit smoking; secondly, some of those who would otherwise have begun to smoke used snus, and thirdly because some smokers smoked less by supplementing with snus (Lund, 2014).
Access to snus cannot replace the usual interventions against smoking (information, restriction and help to quit) but when good anti-smoking programmes are established, snus can result in a significant reduction in smoking (Lund, 2014).
Passive smoking and health hazards
Children and adolescents who are exposed to passive smoking are at greater risk of respiratory infections, ear problems and asthma, particularly for children under 2 years of age, regardless of whether there are one or more smokers in the household. However, the effect is strongest if the mother smokes. In addition, passive smoking contributes to infections becoming more serious (Burke, 2012; Huttunen, 2011; Jones, 2011).
The decline in smoking in the population has also led to a decline in the number of people exposed to passive smoking. This applies both in the workplace and in the home.
- While 25 per cent of workers were exposed to passive smoking at work in 2002, this was 5 per cent 10 years later.
- The number of those exposed to passive smoking in the home dropped from 20 per cent in 2005 to less than 10 per cent in 2012 (Directorate of Health, 2013). In 2014, 93 per cent reported that they never or almost never stayed in a room in the home where someone smoked, while six per cent reported that they lived in such rooms (Statistics Norway, 2016).
- At the same time as the decline in smoking, the attitudes towards smoking indoors have changed. 97 per cent of respondents reported that they completely agreed or partly agreed with the statement "Nobody is allowed to smoke in my house when children are present" (Statistics Norway, 2016).
After the ban on smoking was introduced at catering venues in 2004, waiters and restaurant workers had better health; They experienced a decrease in symptoms of respiratory disease and an improvement of lung function (Eagan, 2006; Skogstad, 2006). The global disease burden project has estimated that 120 deaths in Norway could be attributed to passive smoking in 2015.
Interventions against tobacco use
Tobacco use has decreased in line with systematic interventions, information and help to quit smoking, as shown in Figure 6. However, prevention of smoking-related health injuries and nicotine dependence is still important for public health work.
Norway has joined the World Health Organization's Non-communicable Disease Strategy which aims for a reduction of 25 percent in premature death from the four major non-communicable public diseases by 2025. Premature death is defined as before 60 years old. Smoking is the only risk factor involved in all four of the disease groups; Cardiovascular disease, diabetes, COPD and cancer (HOD, 2013).
Research into prevention shows that different types of interventions should be combined for a good effect (Rosen, 2010; Aarø, 2009).