Once the number of smokers has been reduced to approaching one-fifth of the adult population in a country where it was much higher, the fall in numbers slows down, then stalls at around 20% . No further significant reduction is possible using the same methods. This can be stated as follows:
"Once smoking prevalence is reduced to around 20% of the adult population in a developed country where efforts are made to reduce smoking from the typical level of 40% or higher, no further significant reduction occurs by continuation of use of the methods generally used for reduction to that level."
There are no known exceptions to this rule: there is no country to which the 20% Prevalence Rule applies that does not comply.
Education, public health campaigns, high taxes on cigarettes, an advertising blackout, indoor smoking bans, smoking cessation assistance and so forth can reduce smoking prevalence to about 20% of adults (which is about one-sixth of the total population); opinions vary on the significance of these various methods and it is not our topic area. After that point, no great reduction using these methods or similar can be made. Only substitution works after the 20% mark is reached in a country where smoking prevalence was originally much higher.
The fact that prevalence reduction stalls at around 20% has been pointed out by Carl Phillips for many years, together with its remedy by substitution. There is debate about whether it is a rule or simply an empirical fact. Research is needed on the exact figures - for example, is 40% the minimum qualifying figure for the Rule to operate?
The naming of this rule is informal, and debated, because we do not have the precise facts - is the stall-out point exactly 20% (which seems unlikely)? Is the minimum qualifying point 40% (exactly)? And so on. Since it can be seen to exist, and there are no exceptions (but logically there should be, if no rule exists), and because the corollary is proven, then some form of rule, law or principle must presumably operate.
A corollary to the 20% Prevalence Rule is the following:
"When the 20% Prevalence Rule operates, the only proven way to significantly reduce smoking further is by unhindered access to Tobacco Harm Reduction products, for consumer substitution of alternative smoke-free products for cigarettes."
In other words, once prevalence has reduced to around one-fifth of the adult population from a much higher figure that exceeded 40%, only the freedom to substitute low-risk consumer products for cigarettes can produce reductions of any significance after that point. Substitution is also called switching, or 'switching to a safer product'.
We know this is true because (1) the drop in smoking prevalence has stalled out around 20% in many countries - for example, there was no fall in smoking prevalence in the UK between 2008 and 2013, despite enormous sums being spent, and indeed the number of smokers grew slightly (see 2015 Update at end); and (2) Sweden is the only country where very great reductions in smoking prevalence past the 20% point have taken place, and this is entirely due to free access to THR products (in this case Snus). In fact male smoking prevalence falls at 1% per year in Sweden, and has done so since 2003 when it was 17%, and will be just 5% by around 2016, entirely due to Snus uptake.
Note that a 5% level of smoking prevalence is regarded by some in Public Health as the target for "non-significant smoking prevalence", aka 'the endgame' target.
Are there exceptions to 20PR ?
There are no exceptions to the rule. It applies to countries where smoking prevalence was originally much higher, apparently those where it was above 40%. All comply with 20PR.
In general these appear to be developed countries, and therefore in the West (most / all European countries for example). In some developed countries (perhaps more accurately: 'semi-developed' countries) that had a very low smoking prevalence, we don't know what prevalence levels will fall to before they stall out (if at all); but there are very few such countries and they are not generally located in the West; and there are some caveats concerning a description of them as 'developed'.
We don't know much about the 20% Prevalence Rule, how or when it operates, and if it can be accurately described as a rule or not. The problem is that admission of its existence would be financially problematic for the tobacco control industry, who are extremely well-funded and well able to suppress such information. Essentially, its existence means that the TCI is redundant, so broadcasting the issue will not be well-received in the Public Health industry (since public health per se is not the principal driver for organisations in this area; maintaining their funding sources and employment is).
You can immediately see that if smoking prevalence reduction stalls out at around 20% in countries where it was originally at least double that (as it does), and if the traditional methods then no longer work (as they don't), no matter how vast the sums of money expended are (which are in effect poured down the drain), and if only THR can then reduce smoking prevalence significantly (as is the case), and if admitting this fact would result in job losses within the Public Health industry (as it would), and if suppressing information about the 20% Prevalence Rule accompanied by resistance to THR is equivalent to promoting smoking and protecting cigarette sales (as it most assuredly is - QED), then it clearly follows that the Public Health industry, by and large - though not everyone in it - is a corrupt, self-serving and harmful enterprise that protects disease and death for personal gain.
Reduction by THR
In practice, for substitution to work optimally, it appears to require unhindered and unrestricted access to a full range of products limited only by market forces. This has no risks additional to those normally experienced with any consumer product as long as normal consumer protections are in place; this assessment is confirmed by the Swedish experience.
For contrasting opinions see the final paragraph, below.
Calculation of prevalence figure
The method of calculating smoking prevalence within a population also affects any numbers used, and in practice it is very unlikely that the statistics themselves are reliable: there are at least 4 versions of what is supposed to be the same figure just for the UK, which in theory ought to have easily-obtainable and universally agreed stats - this is certainly not the case. Some say that the 'past month' figures should not be used anyway, because the 'daily smoker' figure is better.
Whichever is used, since there are multiple versions of the same figure for a place like the UK, it seems likely that the same applies to other countries and the figure cannot be relied on as fact. In early 2013 we have seen opinions and official figures for smoking prevalence in the UK varying between 18% and 23%, and with such a wide variation seen, the only conclusion that can be reached is that the prevalence figures are simply guesses. The UK government, the Dept of Health, the EU, and the OECD do not agree what figure represents smoking prevalence in the UK; even when apparently measured the same way with the 'past month' figure.
And crucially, of course:
Since it is obvious that the prevalence of smoking will be significantly higher than that reported, exactly what steps were taken by those conducting the surveys to correct the under-reporting? Did they, for example, just add 1 point to the total? 4 points? Or what?
Anyway, our job is not to decide who is right (as this seems difficult or impossible, and is not within our topic area), just to use the available statistics to demonstrate issues in the clearest, simplest way. It is hard, perhaps even impossible except for those within the medical/research world, to obtain the smoking prevalence statistics for every country using anything other than the 'past month' figures, as these are the stats widely published.
Because even the figure for the same statistic in the UK varies by around 5%, with the EU reporting it as 23%, the UK gov at 21%, and others at a lower figure, we use an average as it seems our only option - we would take 21% @2012 as a median figure and the 'best bet' (since that is clearly all it is).
Currently there is less evidence for the argument that only substitution works effectively after the 20% barrier is reached. It is strongly demonstrated in Sweden; a similar effect is seen in other Nordic counties, and in some US States where oral tobacco has also been traditionally used.
The Swedish experience is particularly clear:
Note that the EU does its best to hide all the above facts, for reasons unknown. From the Swedish experience, we can see that unhindered substitution is not just a marginal process, it produces dramatic falls in smoking and the related disease and death rate. This contrasts starkly with the stall in smoking prevalence reduction in other European countries such as the UK. It also has zero cost to the taxpayer.
It appears that:
The existence of the 20% Prevalence Rule is disputed. Here are some criticisms:
Carl Phillips : Does not agree this is a rule, since it may have no rule-like properties and may simply be an empirical fact. Education can reduce smoking prevalence to around 25%; then tax rises on cigarettes get the figure down to 20% or so; after that, substitution is the most effective route.
('Substitution' is the consumer purchase of alternative consumer nicotine or smokeless tobacco products for use instead of cigarettes. Such products include e-cigarettes and Snus.)
Bill Godshall : Does not agree with the current convention of measuring smoking prevalence using the 'past month' figure; he says that 'daily smokers' is a more correct measurement, and that the 'half pack daily or more' measurement would be even more accurate. As I understand it, by this he is referring to the continuum of risk and therefore the level of harm caused, such that (for example) >half-pack daily smokers are at risk, <half-pack smokers are at less risk, past-month (occasional) smokers have much less risk.
So, if this point has been correctly understood, he is saying that use of current smoking statistics is wrong since the stats do not represent the percentage of the population at risk, because a proportion of those included are not at significant risk as they are occasional smokers; and that smoking statistics should represent those at risk, not 'social smokers' and so on who may perhaps have no measurable risk. This would be correct, if risk can be measured in pack-years and the figure needs to be significant before elevation of risk is demonstrated.
The 'daily smoker' figure is harder to locate since available stats give the usual 'past month' figure (although it varies considerably just for the UK according to source, and the concept that it is accurate for multiple countries is not logical; such statistics must be inherently unreliable).
Therefore, he disputes the 20% rule because the prevalence calculation basis is incorrect in the first place. In addition, he believes other methods can also reduce prevalence after that point (which is understandable if the 'half-pack +' figure is used, because those smokers might be persuaded to cut down, which would remove them from the stats). There is also the very important factor of oral tobacco use in the USA to consider: Americans have always used THR products, so that where smoking prevalence is low, oral tobacco use may be common (and thus a THR solution to the 20% Prevalence Rule is already in play).
Note: Brad Rodu reports there are around 8 million ST users in the US, which accounts for the lower smoking prevalence than that expected (c. 19% @2014). This appears to indicate that without this THR product use the US smoking prevalence rate would be about 22%.
Bill also talks about daily dependence, which is a good point: if a person does not smoke daily, then exactly how dependent are they? So perhaps dependence should be measured by 'daily dependence', as a more accurate marker of real dependence as against occasional or social use. In practice, finding the 'daily use' number for all countries is not a realistic proposition (apart from Australia, which tends to use this number exclusively for some reason; perhaps because it presents Aus favourably when compared to other countries, if the observer is not familiar with the
deception method used).
This article was originally written some years ago and many of the stats are appropriate to that era. An attempt has been made to update figures where necessary.
USA and smokeless tobacco
Brad Rodu reports that there are around 8 million ST users in the USA , and such a large number clearly has a significant effect on the US smoking prevalence figure.
US smoking prevalence is reported at 2014 as about 18.8%, and it is obvious the figure would be several points higher without ST use, with ~45m smokers and 8m ST users. Like Sweden, the US has had a significant THR effect working for many years. Historically, oral tobaccos in America were associated with oral cancer (though never as much as cigarette smoking, of course, which has the highest risk for oral cancer of any consumer product anywhere - Bill Godshall says that smoking has a ten times greater risk for oral cancer than any form of ST use), but modern US products show no such association. Indeed the TSNA analyses (measurement of carcinogen presence) show comparable levels to Snus, which has no identifiable association with any form of cancer.
UK smoking prevalence bottomed out at around 20% in 2008, and stayed static for 5 years until 2013 according to the ONS. Then the ecig effect began to be seen, and it is crystal clear that the reduction in smoking prevalence from 2013 on is due entirely and solely to vaping. Indeed, the figures align perfectly: the subsequent reduction in smoking prevalence equals the number who quit via vaping (R West and others have shown that more than 1 million UK smokers have ceased smoking by vaping and by total cessation through vaping). More than 10% of UK smokers quiitting via ecigs just from 2012 (or thereabouts) to 2015 is quite impressive. It also points up nicely why certain parties are very worried indeed.
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 a. When using the normal 'past month' smoking prevalence figure that published national statistics are usually based on.
b. We cannot be sure that the figure is exactly 20% (and this would in any case be unlikely). Without proper research all we can say at this time is that it appears on average to be around the 20% point.
c. There may be additional factors that increase or reduce the exact point for any given country even when the rule applies; for example it looks as if the point may have been 22% in the UK (although it is difficult or impossible to be exact as we do not know which version of the smoking prevalence statistics is correct - there are multiple versions of the same statistic).
d. In any case, we now have around a 1% to 2% reduction in smoking prevalence in the UK entirely due to e-cigarette uptake, which makes calculation even more difficult.
 A developed country that never had high smoking prevalence (perhaps for cultural or ethnicity reasons) is excluded by the terms of the 20% Prevalence Rule. As an example Australia originally had a comparatively low smoking prevalence of around 25%, which was less than half that of some European countries (male smoking prevalence in the UK is reported as high as 80%+ in the late 1940s - ASH UK), and therefore in AUS it was possible to reduce smoking past the 20% point with little effort. Presumably they will reach their own stall point although we don't know where that will be.
 It is variously stated that 0.6% or, alternatively, that 1% of all smokers in any given developed country will die in any one year. Observation appears to suggest that a figure about halfway between these two seems to accord with official smoking mortality statistics: around 0.75%. ASH UK say (at Q2 2013) that for every 1 smoker who dies, another 20 are ill. This means, if correct, there are currently 2 million smokers being treated for related illness (as 100 thousand reportedly die from smoking per year in the UK).
 CV Phillips was Professor of Public Health at Alberta University and now consults. He is a leading authority on the science base for Tobacco Harm Reduction, and his work provides the foundation for much of the science basis for current THR debate.
 WT Godshall, Director of Smokefree Pennsylvania, is the world's most active anti smoking harm campaigner and has been for several decades. He is an authority on US smoking law and regulatory processes.
 ST (smokeless tobacco) includes nasal snuff, so the meanings of 'ST' and 'oral tobacco' are different.
>> Snus and ST, #15.
last update 2015-07-14