Ruslan Alekso/Pexels, Ketut Subiyanto/Pexels, Darya Kameneva/Unsplash, The Conversation, CC BY-SAThe upcoming social media ban for people aged under 16 continues to be hotly debated.Bans in public policy are a blunt instrument with a mixed track record of success. Some issues are better suited to a ban than others.So what determines the success or failure of banning and what can be done instead? A brief historyBans, differing in scope, method and duration, have featured in public policy over time and across a range of areas. These have mostly been aimed at preventing harm.These can be blanket bans (such as recreational vaping), or efforts to strongly disincentivise certain things. Gun control laws worked to disincentivise gun ownership. Following the national gun buyback scheme after the Port Arthur Massacre, there was not a single mass shooting in Australia for more than 20 years.Australia was also the first country in the world to introduce plain packaging for tobacco products. The move aimed to discourage people from taking up smoking and reduce the appeal for those who already smoked.A 2015 independent study found 25% of the decline in smoking prevalence was attributable to plain packaging. Slow off the markIn other areas, preventative action has been slow at state and federal levels. For instance, when the Whitlam government first moved in 1973 to phase out tobacco advertising, the United Kingdom and United States had already banned it. The connection between cigarette smoking and lung cancer had been evident since the 1920s. Two studies had been published in the 1950s linking smoking to lung cancer, but the tobacco lobby had been searingly strong.Today, Australians suffer the highest losses and greatest harm due to gambling per adult anywhere in the world. But Australian governments have lacked the political will to do much about it, including banning gambling ads. How do we change behaviour?Something all these policies have in common is the aim to change people’s behaviour to reduce harm.But key to this is establishing whether you need policy to change a population’s behaviour, or policy to change the behaviour of individual people, or both.In the field of public health, for instance, the most important thing to work out is whether you are dealing with sick individuals (treating the person at high personal risk of disease) or a sick population (which means focusing on modifying environmental or societal factors causing disease across the population).By focusing on solutions at the level of the individual, we have often led public policy astray by neglecting to address the broader picture. So how can make policy for all of society?We can learn a lot about societal solutions from a somewhat unlikely case study: reducing salt intake. Salt is an essential micronutrient and a much-needed preservative. But high salt consumption is linked to elevated blood pressure and hypertension, largely due to the sodium contained in salts.Many studies have researched peoples’ blood pressure problems and left it up to them to change their daily habits Salt intake has often been left to individual people to manage, but salt is everywhere and can be hard to avoid. Emmy Smith/Unsplash But can we act at a population level instead? In a community-wide salt replacement initiative in northern Peru, in which one of the authors of this article took part, we swapped regular salt for another salt containing potassium and less sodium. We made this replacement in households, shops, bakeries. And with food street vendors, community kitchens and restaurants. It was a “mass replacement” for the entire population.The result was not only reduced high blood pressure in all villages, including in young adults, but was also fewer new cases of hypertension. The reduced availability of salt led to better outcomes at the individual, population and system levels.Social media, like salt, is also widely available and part of everyday life. Asking people not to use it for their own good is rarely effective in the face social pressure. This is why restricting access to those under 16 is a good example of policy to reduce harm at the population level.Providing real alternativesBut as any parent or salty food fan will know, when you take something away, you need to offer something in its place. The Peru study didn’t ban salt, it replaced it. When supermarkets phased out plastic bags, biodegradable or paper ones were provided instead. People trying to drink less can buy non-alcoholic alternatives.For broad restrictions to be effective, there needs to be, among other things, an alternative: something that actually fulfils the deep, underlying human needs that were fuelling use in the first place.This is a central challenge to the social media ban. If the desired replacement is real social connection, there needs to be a clear way to achieve it. Accessible and engaging after-school care has high potential in this regard. Framing the debateThe way we talk about banning something also contributes to its effectiveness and public support. Preventative action can be perceived as either prohibition or abolition. Prohibition means stopping someone from doing something, potentially something they used to be able to do. That can create a sense of deprivation.Alternatively, if people believe something is worth abolishing (not just prohibiting), they think it allows them to have greater freedom to live lives they value. The ban on single-use plastics focuses on harm reduction for the environment. Although it took some 20 years for all states and territories to ban them, it’s been relatively uncontroversial. The benefits are significant and the substitutes feel good. One of the challenges with the social media ban is the way it is seen (by adults and kids alike) as the adults taking something away from the kids, thereby prohibiting it. Instead, the government could frame the ban differently. They could say by abolishing social media use for under 16 year olds, it gives kids the best possible childhood, free of online harm. Overall, good public policy to reduce harm assesses whether the action should be individual or society-wide, offers an effective replacement and frames the change positively. As we head towards the December 10 implementation of the social media ban, these will be important factors for the government to consider.Kate Harrison Brennan was an advisor to Prime Minister Julia Gillard. She has received funding from the Paul Ramsay Foundation for the Australia Cares project at the Sydney Policy Lab. The Sydney Policy Lab has: a project with funding from a Social Determinants of Health Innovation Grant from the Ramsay Hospital Research Foundation; a partnership with SEED Futures, engaged on primary prevention in the early years; and a project with the Brain and Mind Centre at the University of Sydney on Beyond the Bell - rethinking after school hours in Australia. Kate serves on the Advisory Council of SEED Futures.Jaime Miranda acknowledges having received funding support from the Academy of Medical Sciences, Alliance for Health Policy and Systems Research, Bloomberg Philanthropies (via University of North Carolina at Chapel Hill School of Public Health), FONDECYT, British Council, British Embassy and the Newton-Paulet Fund, DFID/MRC/Wellcome Global Health Trials, Fogarty International Center, Grand Challenges Canada, International Development Research Center Canada, Inter-American Institute for Global Change Research, National Cancer Institute, National Council for Scientific and Technological Development, National Health and Medical Research Council, National Heart, Lung and Blood Institute, National Institute on Aging, National Institute for Health and Care Research, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Mental Health, NSW Health, Medical Research Future Fund, Swiss National Science Foundation, UK Research and Innovation, Wellcome, World Diabetes Foundation and the World Health Organization.He is affiliated with the following academic organisations: Professor at the Department of Medicine, School of Medicine, and founding Director of the CRONICAS Centre of Excellence in Chronic Diseases, both at Universidad Peruana Cayetano Heredia (Peru); Honorary Professor at the London School of Hygiene and Tropical Medicine (UK); Lown Scholar at the Harvard T.H. Chan School of Public Health (USA); and Distinguished Fellow at The George Institute for Global Health (Australia). He is also a member of the Advisory Board of the InterAmerican Heart Foundation (IAHF); and member of the Scientific and Technical Advisory Committee (STAC) of the Alliance for Health Policy and Systems Research at the World Health Organization.