Tuesday 19 July 2022

Smoke without fire?

A study titled 'Should IQOS Emissions Be Considered as Smoke and Harmful to Health? A Review of the Chemical Evidence' was published two weeks ago. The study comes with a big red flag:

The authors acknowledge the support of Bloomberg Philanthropies’ Stopping Tobacco Organizations and Products funding (www.bloomberg.org). The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript. The authors also thank Prof. Anna Gilmore and Sophie Braznell from the University of Bath and Dr. Ed Stephens from the University of St. Andrews for valuable discussions and reviewing the content of this article.

Why anyone would ask advice from Anna Gilmore and one of her PhD students when writing about chemistry is a mystery that is only partially solved by the knowledge that they are also on the Bloomberg gravy train. Gilmore is deeply involved with Bloomberg's 'Stopping Tobacco Organizations and Products' (STOP) front group. How can the funder be said to have had no role in the analysis when she reviewed and commented on the study? I guess different rules apply in 'public health'. The authors report no conflicting interests.

IQOS is a heated tobacco product produced by Philip Morris International (PMI). It doesn't burn the tobacco, it heats it. Consequently, there is no smoke and the products are considerably safer than combustible cigarettes. This has been acknowledged in the UK by the Committee on Toxicity and in the USA by the Food and Drug Administration (FDA). The FDA allows IQOS to be marketed as a Modified Risk Tobacco Product, an honour that is rarer than hen's teeth and requires an abundance of evidence to earn.

Mike Bloomberg and his minions loathe reduced risk nicotine products and are determined to crush them, even if it means turning scientific terminology on its head. One strategy is to portray the emissions from heated tobacco products as 'smoke'. This has regulatory implications in many countries and this new study seems designed to be printed off by campaigners and laid on the desk of gullible regulators. It concludes:

The HPHCs [harmful and potentially harmful compounds] present are the same as in conventional cigarette (CC) smoke, albeit in lower concentrations and formed at lower temperatures, analogous to the emissions from the earlier generation of HTPs [heated tobacco products], which were classed as smoke. Also, IQOS emissions contain carbon particles with most of the compounds released being formed by chemical reactions provides further evidence that IQOS emissions fit the definition of being both an aerosol and a smoke.


Unlike Anna Gilmore, I am happy to admit that this is beyond my expertise so I invited Dr Roberto Sussman from the Institute of Nuclear Sciences at the National Autonomous University of Mexico to write a guest post. Here is what he has to say...


“Must a name mean something?” Alice asks Humpty Dumpty, only to get this answer: “When I use a word… it means just what I choose it to mean – neither more nor less.”

Paraphrasing this Alice in Wonderland dialogue with “a name” replaced by “smoke” and “Humpty Dumpty” replaced by “Tobacco Control orthodoxy” illustrates the determination of the WHO technocracy to attach the term “smoke” to the IQOS aerosol. Earlier this month, scientists funded by Bloomberg Philanthropies attempted in this article to provide technical backbone to this “re-classification” of IQOS aerosol as some form of smoke. It was written by Clement N. Ugana and Colin E. Snape, both from the University of Nottingham's Faculty of Engineering.

Let us first clear the semantics: What is “smoke”? Any textbook on aerosol physics defines “smokes” as aerosols (particulate substrate in a gaseous medium) sharing the following characteristics:

  • the particles are fine and ultra fine (diameters less than 1 micrometer)
  • can be solid or liquid
  • are generated by a combustion process.

What is a combustion process? Chemical reactions that involve a combustible are oxidizing and exothermal (i.e. require oxygen and external energy supply).

So how do Uguna and Snape claim that IQOS aerosol can be characterized as a “smoke”? Basically, they follow the suggestion of a questionable 2017 paper by Auer et al. titled 'Heat-not-burn tobacco cigarettes: Smoke by any other name' which claims that IQOS aerosol contains “compounds from pyrolysis and thermogenic degradation that are the same HPHCs as for conventional tobacco cigarette”. 

Uguna and Snape extend this to :

  • The same endothermic physicochemical processes that occur when inhaling cigarette smoke might occur in IQOS aerosol: evaporation/condensation of vapors, distillation (separation of liquid/solid phases), pyrolysis and pyro-synthesis (larger molecules decomposing in smaller ones and and recombining).
  • IQOS aerosol contains detectable solid black carbon particles (a generic name for carbonaceous particles)
  • Some spots in the tobacco of the IQOS might reach higher temperatures than the recommended range below 350 C

Uguna and Snape are mistaken in assuming that IQOS aerosol can be cast as a smoke on all these counts.

Let us deal with the first issue. While there is no smoke without combustion (or without oxygen), different smokes might evolve through many other derived physicochemical processes, such as the ones mentioned by Uguna and Snape. However, these are derived processes acting on smoke that has already been produced by oxidizing exothermal reactions. In other words: these processes are not needed to generate a smoke and their occurrence does not by itself imply combustion. This is easily illustrated by looking at the specifics of tobacco smoke.

What we call “tobacco smoke” is really two distinct aerosols, both originating from the same smoke produced by the burning (external energy supply) of the combustible (tobacco leaf). Each aerosol evolves differently: the sidestream emission making 75-80% of the produced smoke at the burning (800-900 C) and smouldering (450-500 C) tip of the cigarette is directly released to the environment and the mainstream emission, the remaining 20-25% that is inhaled by the smoker and undergoes several physicochemical processes, such as distillation, condensation/evaporation, pyrolysis and pyro-synthesis and forced convection and cooling (from 800-900 to 40 C) as the smoker inhales through the cigarette rod.

The confusion of Uguna and Snape is clear: they assume that the IQOS aerosol can be a sort of “smoke” because it may go through some (or even all) of the derived processes (condensation/evaporation, distillation, pyrolysis) in the evolution of 20-25% of the cigarette smoke that forms the mainstream emission of cigarettes. However, such processes do not define combustion and are not necessary to generate smoke (for example, sidestream smoke). Neither are they sufficient to do so: they can occur without combustion with exothermal processes that do not involve oxidizing reactions.

The lack of combustion in the aerosol generated by a heated tobacco device was proven in a rigorous experimental test by PMI scientists (Cozzani et al. 2020). A heated tobacco device in an oxygen-free laboratory environment was capable of aerosol generation. This proves that the aerosol was not generated by combustion, which is an exothermic oxidation process that cannot occur without oxygen and a combustible.

Evidently, depending on the temperature (and thus on the supplied battery power) in which the heated tobacco device is operated, the derived processes (distillation, condensation/evaporation, pyrolysis or pyro-synthesis) might occur in the aerosol evolution, but this does not prove that the generated aerosol is a smoke because 20-25% of cigarette smoke undergoes similar processes. The key difference is that this fraction of tobacco smoke was previously generated by combustion, whereas Cozzani et al. proved that the aerosol from a heated tobacco device is not.

Another reason why Uguna and Snape claim that IQOS aerosols can be characterized as some sort of smoke is the presence of black carbon solid particles. The particulate phase of IQOS has been examined in laboratory studies by the industry, in particular by two comprehensive laboratory studies (the second funded by PMI): Pacitto et al. (2018) and Amorós-Pérez et al. (2022).

Although neither of these is cited by Uguna and Snape, both laboratory studies concluded that particles in IQOS aerosols are quite distinct from those of tobacco smoke that are clearly identifiable with combustion particulate matter (PM). They have much larger volatile content and are overwhelmingly liquid and produced by condensation. Uguna and Snape only cite several sources that have detected black carbon particles in minute concentrations relative to tobacco smoke (for example, less than 1% in Ruprecht et al.). They cite Auer et al., which merely speculates on IQOS aerosol particles.

While Uguna and Snape recognise that IQOS operates at temperatures of less than 350 C, considerably below combustion temperatures, they hint that the tobacco undergoes an inhomogeneous heating, with the creation of spots possibly reaching higher temperatures. However, this is mere speculation without any actual laboratory proof under normal operating conditions of the devices.

It is really unnecessary to go any further on re-classifying IQOS aerosols as smoke, in the presence of black carbon particles, or in arguing that its toxicity may be comparable to that of tobacco smoke, as these claims were irrelevant in the extremely rigorous testing of the characteristics and relative safety of product that was validated by the FDA in its review of the PMTA application submitted by PMI. The FDA openly recognised that its evaluation roughly agrees with the claims by the manufacturer on all technical issues, with substitution of cigarette smoking by usage of an IQOS device representing for users a significant reduction of their exposure to HPHCs, thus granting the devices the status of “appropriate for the protection of public health”.

Going back to the semantics: perhaps the definition of “smoke” can be stretched to include any aerosol with (even a minimal) presence of solid non-volatile particles and undergoing any one (or all) the physicochemical processes in the formation of the mainstream emission inhaled by smokers. After all, other than the need to facilitate scientific communication, there is nothing sacred about terminology. While stretching the definition of smoke in this way would encompass aerosols from heated tobacco products (HTPs), it would make communication harder and more confusing by also encompassing aerosols that mostly originate from combustion sources (such as cooking aerosols and air pollution) which are not known as “smokes”. Therefore, it could be counterproductive.

Finally, it is interesting to inquire why the pressing need of tobacco control orthodoxy to characterise aerosols from HTPs as smokes? The main reason is political: this characterisation fulfills the need of the technocracy to keep the ongoing crusade against the manufacturers of these devices: the tobacco industry and in particular Philip Morris International (PMI). For this purpose the technocracy is now missing the target of reducing cigarette smoking and giving more preference to keeping the industry in its eternal role of the ultimate evil force deceiving the public. However, the industry's claim that replacing tobacco cigarettes with HTPs such as IQOS significantly reduces user exposure to harmful compounds has been scientifically validated by the US FDA, whereas the most extreme of contrary claims have been only validated by politics and technocratic hubris.

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