Across 40 years of working in tobacco control, there have been countless times when I've been asked "so, has [insert here] policy or [insert here] campaign worked?".
The question has its roots in clinical interventions where we see what happens when you take an analgesic for pain, get an injection before having a tooth pulled, or apply a fungicide on athlete's foot. These things work.
So it's natural we should ask the same about a piece of legislation or a multi-million dollar TV campaign about smoking. Do these things make a difference?
In 1993, I wrote an essay on this issue in the British Medical Journal, Unravelling gossamer with boxing gloves: problems in explaining the decline in smoking.
In the wake of Philip Morris being ordered to pay the Australian government about A$50million in legal costs over the company's failed attempt to thwart plain packaging, I was asked the question again this week: "Has plain packaging worked?"
So here's an update on the direct and subtly synergistic ways tobacco control has seen Australia achieve record lows in both adult and teenage smoking.
From a trickle to a deluge
Since the bad news on smoking and health began to trickle in from 1950, then deluged us, hundreds of millions of smokers have stopped smoking around the world, particularly in nations where governments have introduced population-focussed laws and regulations. These include measures like laws, taxes and mass campaigns that reach huge proportions of the population as opposed to dinky little interventions very few people ever see or are exposed to.
When a smoker decides to quit, they will have usually tried before – many with about the same conviction as attempts to exercise more or lose weight. But when they finally succeed, ex-smokers will often nominate a reason "why" they quit.
There is broad daylight between the first reason ex-smokers give about why they quit and all other reasons they nominate. Health concerns are the overwhelming reason for quitting (91.7%), followed by cost (way back at 58.7%); 90% of smokers regret they ever started.
The straw the broke the camel's back
People also often nominate a recent "straw that broke the camel's back" as the precipitating reason for the final decision to quit and resolve to see it through.
This can be a symptom they have experienced, an incident like the sudden death of a smoking friend, a particularly poignant campaign advertisement they can't get out of their head (this classic has few peers), the heartfelt pleading by a child or partner, the sudden realisation very few of their colleagues or friends smoke or the price of cigarettes going through a psychological barrier, like A$40 a pack.
These triggers are known as proximal factors that stimulate quitting: factors easily identified, nominated by smokers aware of their influence, and sometimes easy to quantify with proxy measures like immediate boosts in calls to quitlines.
Background factors that eat away at smoking
But there are also vital distal or background factors that work like hidden termites in a building. These slowly and subconsciously eat away the foundations of smokers' feelings of being invincible to disease, their apathy and act to denormalise pro-smoking environments. The effect is that smokers get fewer reminders about smoking and a growing awareness smoking is not something the great majority of people do anymore.
Examples of these distal factors are advertising bans, graphic warnings on packs, plain packaging, smoke-free public spaces and tobacco taxation.
Very few smokers tell you they quit smoking because tobacco advertising was banned.The impact of advertising bans instead works in slow-burn fashion, as it has done in Australia since 1993 when the last forms of advertising ended.
With plain packs, some smokers experienced an increased urgency to quit after exposure to the purposefully unappealing plain packs with their goullish (but deadly accurate) large graphic health warnings. But the primary goal was to have whole generations grow up never having being beguiled by the designer edginess of pack livery and noting plain packaging of tobacco products was exceptional among all other consumer goods.
Tobacco is the only product where legislation mandates plain packaging: 17 nations have either implemented, legislated it or announced they will. Tobacco is also the only product that has to be stored out of sight in retail outlets.
All these factors do not act in isolation, but like a constant and unstoppable termite colony, working in synergy to erode the appeal of smoking.
A day in the life of an ex-smoker
In my 1993 BMJ essay, I described a day in the life of a smoker who quit. The smoker woke to news on the radio of yet more bad research news about smoking; lived with disapproving family members who often urged him to quit because they had been educated about the risks; winced every time at the price he had to pay for a pack; was acutely aware of all the places he couldn't smoke and why those laws had been introduced; was self-conscious about the stench of stale tobacco he carried about; and couldn't shake some of the powerful anti-smoking advertising that intruded his TV viewing.
A smoker might well nominate just one of these influences when a researcher calls, but all play a part in a comprehensive approach to reducing the world's leading cause of death, if you exclude poverty.
Humans are not like lab rats who can be artificially kept in strictly controlled environments and exposed to single or fixed combinations of policy variables while isolated from all others so researchers can measure the exact impact of any one factor.
People whose questions are based on that premise need to be gently reminded of that. Male lung cancer incidence rates today were last seen in the early 1960s and women's seem likely to never reach even half the peak seen at the height of the male epidemic. We need to stay the course and make smoking history.
Explore further: Study finds plain packaging helps smokers quit