The 20% Prevalence Rule

The 20% Prevalence Rule

Once the number of smokers has been reduced to approaching one-fifth of the adult population in a country that 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 the continuation of use of the methods generally used for reduction to that level.”

There are no known exceptions to this rule: every country subject to the 20% Prevalence Rule follows it.

The reduction in adult smoking prevalence to about 20% of the population (which is roughly one-sixth of the overall population) can be achieved by educational campaigns, public health initiatives, high taxes on cigarettes, a tobacco advertising ban, indoor smoking bans, smoking cessation help, and so forth. The efficacy of these various strategies varies.

After that, no significant reduction can be achieved through these techniques or others like them. Only replacement is effective after a country’s smoking prevalence has reached 20%.

For many years, Carl Phillips has noted that prevalence reduction plateaus at around 20%.

There’s a lot of uncertainty about whether it’s a regulation or just an empirical fact. The precise numbers – for example, is 40% the minimum qualifying percentage for the rule to be effective?

Because we don’t have the correct information, the name of this regulation is informal and disputed. Is the stall-out point 20% (which appears unlikely)? Is it 40% (exactly)? And so on.

Since it may be observed to exist, and there are no exemptions (but logically, there should be if no regulation exists), and because the corollary is true, some rule, law or principle must exist.

THR substitution

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, after prevalence has fallen to around one-fifth of the adult population from a much greater proportion that exceeded 40%, only the freedom to substitute low-risk consumer goods for cigarettes can lead to significant reductions after that.

Substitution is also called switching or ‘switching to a safer product’.

We know this to be true since the smoking rate has remained steady at around 20% in several nations – for example, there was no decrease in smoking prevalence in the United Kingdom between 2008 and 2013, despite huge sums being spent, and the number of smokers increased.

Sweden is the only country where substantial decreases in smoking prevalence have been seen after 20% coverage. This is due to free access to THR products (in this case, Snus).

In Sweden, male smoking prevalence drops by 1% each year and has done so since 2003, when it was 17%, and will be 5% by 2016.

Some in public health consider a 5% smoking rate to be the “endgame” objective, which they say is the minimum level that should be reduced.

Are there exceptions to the 20% prevalence rule?

There are no exceptions to the rule. It applies to countries where smoking was formerly more prevalent, such as those with a prevalence of over 40%. Every 20PR country complies.

These are generally considered to be developed nations, so they’re in the West (most/all European countries, for example).

In some developed countries (perhaps more accurately: ‘semi-developed’) with a very low smoking rate, we don’t know what prevalence levels will fall to before they halt; however, there are only a few such nations, and they aren’t usually found in the West; Furthermore, there are certain restrictions regarding their characterization as ‘developed.’

The 20% Prevalence Rule, how it works, and whether or when it can be accurately characterized as a rule are all things we don’t know much about.

The issue is that admitting to its existence might be financially prohibitive for the tobacco control industry, which is well-funded and able to bury such information.

Essentially, the TCI’s existence indicates that it is no longer necessary, so raising the problem will not be well-received in the Public Health industry.

The first thing you’ll notice is that if smoking prevalence reduction stalls out at around 20% in countries where it was previously at least double that (as it does), and if the traditional techniques then no longer work (as they don’t), regardless of how much money is spent (which is effectively poured down the drain)

Reduction by THR

In practice, unrestricted and unimpeded access to a wide variety of goods appears to be required for substitution to work effectively.

There are no additional risks associated with this (aside from those inherent in any consumer goods) as long as normal customer protections exist; the Swedish experience backs up this conclusion.

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